M211897EN-A
User Guide
Vaisala CARBOCAP® Carbon Dioxide Probe
GMP252
PUBLISHED BY
Vaisala Oyj
Street address:
Mailing address:
Phone:
Fax:
Vanha Nurmijärventie 21, FI-01670 Vantaa, Finland
P.O. Box 26, FI-00421 Helsinki, Finland
+358 9 8949 1
+358 9 8949 2227
Visit our Internet pages at www.vaisala.com.
© Vaisala 2016
No part of this manual may be reproduced,
published or publicly displayed in any form
or by any means, electronic or mechanical
(including photocopying), nor may its
contents be modified, translated, adapted,
sold or disclosed to a third party without
prior written permission of the copyright
holder. Translated manuals and translated
portions of multilingual documents are
based on the original English versions. In
ambiguous cases, the English versions are
applicable, not the translations.
The contents of this manual are subject to
change without prior notice.
Local rules and regulations may vary and
they shall take precedence over the
information contained in this manual.
Vaisala makes no representations on this
manual’s compliance with the local rules
and regulations applicable at any given
time, and hereby disclaims any and all
responsibilities related thereto.
This manual does not create any legally
binding obligations for Vaisala towards
customers or end users. All legally binding
obligations and agreements are included
exclusively in the applicable supply
contract or the General Conditions of Sale
and General Conditions of Service of
Vaisala.
This product contains software developed
by Vaisala or third parties. Use of the
software is governed by license terms and
conditions included in the applicable
supply contract or, in the absence of
separate license terms and conditions, by
the General License Conditions of Vaisala
Group.
Table of Contents
1. About This Document........................................................................................ 7
1.1.
Documentation Conventions................................................................................ 7
1.2.
Version Information............................................................................................... 7
1.3.
Related Manuals..................................................................................................... 8
1.4.
Trademarks............................................................................................................. 8
1.5.
Patent Notice.......................................................................................................... 8
2. Product Overview................................................................................................ 9
2.1.
Introduction to GMP252 ....................................................................................... 9
2.2. Basic Features and Options................................................................................ 10
2.3. Operating Principle of CO2 Measurement.......................................................... 11
2.4. Environmental Compensation.............................................................................12
2.4.1.
Temperature Compensation......................................................................... 13
2.4.2. Pressure Compensation.................................................................................13
2.4.3. Background Gas Compensation...................................................................13
2.5. Probe Startup........................................................................................................14
2.6. Analog Output Overrange Behavior.................................................................. 14
2.6.1.
Analog Output Overrange Example............................................................ 15
2.7. Safety..................................................................................................................... 16
2.7.1.
ESD Protection............................................................................................... 16
2.8. Regulatory Compliances......................................................................................16
3. Installation............................................................................................................. 17
3.1.
GMP252 Probe Dimensions................................................................................. 17
3.2. Recommended Installation..................................................................................17
3.3. Installation Accessories........................................................................................17
3.3.1.
243261SP Installation Flange........................................................................ 18
3.3.2. 243257SP Mounting Clips............................................................................. 19
3.4. Power Supply........................................................................................................ 19
3.5. Wiring................................................................................................................... 20
4. Vaisala Industrial Protocol.............................................................................. 21
4.1.
Overview................................................................................................................ 21
4.2. Serial Interface Settings....................................................................................... 21
4.3. Physical Interface..................................................................................................21
4.4. Connecting with a Computer............................................................................. 22
4.4.1.
Installing the Driver for the USB Service Cable......................................... 23
4.5. Accessing Serial Commands from Modbus or Analog Mode......................... 23
4.6. Enabling Modbus Mode from Vaisala Industrial Protocol...............................24
4.7. Changing From Digital Output to Analog Output........................................... 25
4.8. Serial Commands.................................................................................................25
4.9. Device Information and Status...........................................................................27
4.10. Serial Line Output and Communication.............................................................31
4.11. Analog Output..................................................................................................... 39
4.12. Calibration and Adjustment............................................................................... 44
4.13. Environmental Compensation Commands...................................................... 48
4.14. Other Commands................................................................................................ 55
5.
Modbus...................................................................................................................57
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GMP252 User Guide
6. Operating with MI70 Indicator.................................................................... 59
6.1.
Overview of MI70 Support................................................................................. 59
6.2. Basic Display........................................................................................................ 59
6.3. Graphical Display................................................................................................ 60
6.4. Main Menu............................................................................................................ 60
6.5. Connecting Probe to MI70 Indicator.................................................................60
6.6. MI70 Indicator Parts............................................................................................. 61
6.7. Holding and Saving the Display..........................................................................61
6.8. Recording Data.................................................................................................... 62
6.9. Changing Environmental Compensation Settings with MI70 Indicator....... 63
6.10. Calibration and Adjustment with MI70 Indicator............................................ 64
6.10.1. 1-Point Adjustment with an MI70-Compatible Reference Probe............ 65
6.10.2. 1-Point Adjustment with a Reference Gas..................................................66
7. Maintenance........................................................................................................ 69
7.1.
Cleaning................................................................................................................69
7.1.1.
Chemical Tolerance.......................................................................................69
7.2. Changing the Filter..............................................................................................70
7.3. Calibration and Adjustment............................................................................... 70
7.3.1.
Calibration Setup............................................................................................71
7.3.2. Effect of Environmental Compensations.....................................................71
7.3.3. Limits of Adjustment.....................................................................................72
7.3.4. Adjustment Types..........................................................................................72
7.3.5. DRW244827SP Calibration Adapter...........................................................73
8. Troubleshooting................................................................................................. 75
8.1.
Problem Situations.............................................................................................. 75
8.2. Error Messages.....................................................................................................75
8.3. Analog Output Error State..................................................................................77
9. Technical Data.....................................................................................................79
9.1.
GMP252 Specifications....................................................................................... 79
9.2. Spare Parts and Accessories.............................................................................. 82
9.3. GMP252 Probe Dimensions................................................................................ 82
9.4. 243261SP Mounting Flange Dimensions...........................................................83
9.5. 243261SP Calibration Adapter Dimensions......................................................84
Appendix A: Modbus Reference......................................................................... 85
A.1. Function Codes.................................................................................................... 85
A.2. Modbus Registers................................................................................................ 85
A.2.1. Measurement Data........................................................................................ 85
A.2.2. Configuration Registers............................................................................... 86
A.2.3. Status Registers.............................................................................................88
A.2.4. Device Identification Objects...................................................................... 88
A.3. Modbus Communication Examples.................................................................. 90
A.4. Filtering Factor.....................................................................................................92
Technical Support............................................................................................................93
Warranty...........................................................................................................................93
Recycling.......................................................................................................................... 93
2
M211897EN-A
List of Figures
Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6
Figure 7
Figure 8
Figure 9
Figure 10
Figure 11
Figure 12
Figure 13
Figure 14
Figure 15
Figure 16
Figure 17
Figure 18
GMP252 Probe Parts........................................................................................... 9
Probe Cuvette with Mirror and Sensor Chips...............................................11
CO2 Measurement in the Measurement Cuvette....................................... 12
Example of Analog Output Overrange Behavior ......................................15
GMP252 Dimensions.......................................................................................... 17
Probe with 243261SP Installation Flange.....................................................18
Probe in 243257SP Mounting Clips................................................................19
Example of analog output overrange behavior........................................ 43
MI70 Basic Display.............................................................................................59
MI70 Indicator Parts...........................................................................................61
CO2 Reading with Tcomp and Pcomp on MI70 Screen.......................... 64
Probe Compensation Settings on MI70 Screen........................................ 64
Opening the Filter............................................................................................. 70
DRW244827SP Calibration Adapter with Probe Inserted......................73
GMP252 Dimensions......................................................................................... 82
243261SP Mounting Flange Dimensions..................................................... 83
243261SP Mounting Flange Dimensions, Cross Section......................... 83
243261SP Calibration Adapter Dimensions................................................84
3
GMP252 User Guide
List of Tables
Table 1
Table 2
Table 3
Table 4
Table 5
Table 6
Table 7
Table 8
Table 9
Table 10
Table 11
Table 12
Table 13
Table 14
Table 15
Table 16
Table 17
Table 18
Table 19
Table 20
Table 21
Table 22
Table 23
Table 24
Table 25
Table 26
Table 27
Table 28
Table 29
Table 30
Table 31
Table 32
Table 33
Table 34
Table 35
Table 36
Table 37
Table 38
Table 39
Table 40
Table 41
Table 42
Table 43
Table 44
Table 45
Table 46
Table 47
Table 48
Table 49
Table 50
4
Document Versions.............................................................................................. 7
Related Documents.............................................................................................. 8
Applicable Patents................................................................................................8
Analog Output Overrange Clipping and Error Limits................................14
M12 Male Connector...........................................................................................20
Default Serial Interface Settings......................................................................21
Basic Serial Commands.....................................................................................25
Advanced Serial Commands........................................................................... 26
? Command.......................................................................................................... 27
Errs Command.....................................................................................................28
Help Command....................................................................................................28
Snum command.................................................................................................. 29
System Command.............................................................................................. 30
Time Command...................................................................................................30
Vers Command....................................................................................................30
Addr Command....................................................................................................31
Close Command...................................................................................................31
Form Command................................................................................................... 31
Output Parameters for Form Command...................................................... 33
Modifiers for Form Command.........................................................................34
Intv Command..................................................................................................... 35
Open Command.................................................................................................. 35
R Command..........................................................................................................36
S Command..........................................................................................................36
Sdelay Command............................................................................................... 36
Send Command...................................................................................................37
Seri Command..................................................................................................... 37
Smode Command...............................................................................................38
Amode Command.............................................................................................. 39
Aover Command................................................................................................ 40
Asel Command.................................................................................................... 43
Adate Command................................................................................................ 44
Atext Command..................................................................................................45
Cdate Command.................................................................................................45
Ctext Command.................................................................................................. 45
CCO2 Command................................................................................................. 46
Env Command.....................................................................................................49
O2cmode Command...........................................................................................51
Pcmode Command.............................................................................................52
Rhcmode Command.......................................................................................... 53
Tcmode Command............................................................................................. 54
Frestore Command.............................................................................................55
Pass Command....................................................................................................55
Reset Command................................................................................................. 56
Default Modbus Serial Communication Settings....................................... 57
Performance.........................................................................................................79
Operating Environment....................................................................................80
Inputs and Outputs............................................................................................. 81
Mechanics.............................................................................................................. 81
Supported Function Codes..............................................................................85
M211897EN-A
Table
Table
Table
Table
51
52
53
54
Modbus Measurement Data Registers (Read-Only)................................. 85
Modbus Configuration Data Registers (Writable).....................................86
Modbus Status Registers (Read-Only)......................................................... 88
Device Identification Objects.......................................................................... 88
5
GMP252 User Guide
6
M211897EN-A
Chapter 1 – About This Document
1. About This Document
1.1. Documentation Conventions
DANGER! alerts you to a fatal hazard. If you do not read and follow instructions
carefully at this point, death will follow.
WARNING! alerts you to a serious hazard. If you do not read and follow instructions
carefully at this point, there is a risk of injury or even death.
CAUTION! warns you of a potential hazard. If you do not read and follow instructions
carefully at this point, the product could be damaged or important data could be lost.
Note highlights important information on using the product.
Tip gives information for using the product more efficiently.
1.2. Version Information
Table 1 Document Versions
Document Code
Date
Description
M211897EN-A
May 2016
First version.
7
GMP252 User Guide
M211897EN-A
1.3. Related Manuals
Table 2 Related Documents
Document Code
Description
M211893EN
Vaisala CARBOCAP® Carbon Dioxide Probe
GMP252 Quick Guide
M211799EN
Vaisala CARBOCAP® Carbon Dioxide Probe GMP251
User Guide
M211798EN
Vaisala CARBOCAP® Carbon Dioxide Probe GMP251
Quick Guide
1.4. Trademarks
Vaisala® and CARBOCAP® are registered trademarks of Vaisala Oyj.
Windows® is either a registered trademark or trademark of Microsoft Corporation in the
United States and other countries.
1.5. Patent Notice
This product is protected by the following patents and their corresponding national rights:
Table 3 Applicable Patents
Patent Issued By
Patent Number
United States Patent and Trademark Office
US 5,827,438
US 6,177,673
European Patent Office
EP0776023
EP0922972
German Patent and Trade Mark Office
69615635
Japan Patent Office
4263285
Finnish Patent Office
112005
105598
8
Chapter 2 – Product Overview
2. Product Overview
2.1. Introduction to GMP252
GMP252 is designed for CO2 measurement in demanding applications that require reliable
and accurate performance. The measurement range is 0 ... 10 000 ppmCO2 (measurements
can be carried out in the 10 000 ... 30 000 ppmCO2 range with reduced accuracy).
The probe is based on Vaisala’s patented 2nd generation CARBOCAP® technology and
equipped with Vaisala's Microglow infrared light source. The probe is easy to install with a
plug-in/plug-out M12 connection.
GMP252 is able to compensate for temperature, pressure and background gas. For
temperature compensation purposes, the probe includes an internal temperature sensor
that allows measurement compensation according to ambient temperature. As dust and
most chemicals do not affect the measurement, and the effect of temperature, pressure and
background gas can be compensated for, GMP252 can provide accurate and stable
measurements in a wide range of applications.
1
2
3
4
5
Figure 1 GMP252 Probe Parts
1
2
3
4
5
5-pin M12 connector. For pinout, see 3.5. Wiring (page 20).
Probe name and orientation mark for Vaisala transmitter installations (front) and laserprinted type label (back).
Probe body. Contains the main component board.
Measurement cuvette with optics and CARBOCAP® CO2 sensor.
Filter (sintered, PTFE)
CAUTION! Do not attempt to open the probe body. There are no user serviceable parts
inside the probe body.
9
GMP252 User Guide
M211897EN-A
2.2. Basic Features and Options
•
•
•
•
•
CO2 measurement range 0 ... 10 000 ppmCO2.
Measurement up to 30 000 ppmCO2 with reduced accuracy.
Operating temperature range -40…+60 °C (-40...140 ºF).
Vaisala CARBOCAP® CO2 sensor with excellent long-term stability.
Measurement compensated for effects of temperature, pressure, and background
gas. The temperature compensation can be based on an integrated temperature
sensor or use a set temperature. Pressure and background gas parameters can be set
to the probe.
• Heating to avoid condensation on optical elements.
• Digital output with RS-485:
• Modbus RTU
• Vaisala Industrial Protocol
• Analog output:
• Current output (0 ... 20 mA or 4 ... 20 mA)
• Voltage output (0 ... 5 V or 0...10 V)
• Compatible with MI70 hand-held meter.
• Easy plug-in, plug-out.
More Information
‣
‣
‣
‣
‣
10
GMP252 Specifications (page 79)
Operating Principle of CO2 Measurement (page 11)
Environmental Compensation (page 12)
Modbus (page 57)
Overview of MI70 Support (page 59)
Chapter 2 – Product Overview
2.3. Operating Principle of CO2
Measurement
1
The Vaisala CARBOCAP® sensor used in the
probe is a silicon-based, nondispersive
infrared (NDIR) sensor for the measurement
of gaseous carbon dioxide in air-like gases.
Figure 2 Probe Cuvette with Mirror and Sensor
Chips
2
1
2
3
Mirror
Cuvette
Sensor chips under TO5 package
3
The sensitivity to carbon dioxide is based on absorption of infrared light at a characteristic
wavelength. During measurement, infrared light is routed through the cuvette that contains
the gas to be measured. A mirror reflects the light from the cuvette to a thermopile detector
that measures the light intensity at a wavelength determined by a Fabry–Pérot
interferometer (FPI) and a band pass filter.
The carbon dioxide measurement consists of two steps: first, the FPI is electrically tuned so
that its pass band coincides with the characteristic absorption wavelength of carbon dioxide
and the signal is recorded. Second, the pass band is shifted to a wavelength where no
absorption occurs in order to get a reference signal. The ratio of these two signals, one at
the absorption wavelength and the other at the reference wavelength, gives the fraction of
light absorption from which the carbon dioxide concentration is calculated. Measuring the
reference signal compensates the possible effects of sensor aging and signal attenuation
due to dirt on optical surfaces, making the sensor very stable over time.
TO5 packages with hermetic windows are used to protect the sensor chips from moisture
and contamination. A heater chip is utilized to prevent condensation in normal operation.
11
GMP252 User Guide
M211897EN-A
Figure 3 CO2 Measurement in the
Measurement Cuvette
1
1
2
3
4
5
6
7
2
3
4
Gold-plated mirror
Light absorbed by CO2 in the measured
gas
Hermetic window
Fabry-Perot interferometer
Light source (Microglow)
Hermetic window
Thermopile detector
6
7
5
2.4. Environmental Compensation
When necessary, various environmental compensations can be applied to improve the CO2
measurement accuracy of the probe.
The probe can compensate for the effects of the following parameters:
•
•
•
•
Temperature
Pressure
Background gas oxygen (O2) content
Background gas relative humidity (%RH)
To apply an accurate relative humidity compensation, make sure that also the temperature
compensation and pressure compensation configurations match the measurement
environment.
The probe has an on-board temperature sensor that can be used to compensate for
temperature. Additionally, if the probe is integrated in a system that measures one or more
of the compensation parameters (T, P, RH, O2), they can be updated to the probe
continuously.
Compensation parameters are configured on the order form when ordering the probe, and
can later be updated using Vaisala Industrial Protocol or Modbus protocol.
12
Chapter 2 – Product Overview
You can also turn off any of the compensations. In that case, the probe uses the default
compensation value that is mathematically neutral for the probe’s internal compensation
model.
2.4.1. Temperature Compensation
The probe can measure the approximate temperature of the CARBOCAP® sensor for
compensation, or use a fixed setpoint. The temperature measurement is accurate enough to
be useful for compensation, and is recommended for use unless a dedicated temperature
measurement is available and can be regularly updated to the probe. If the measurement is
made in a constant temperature, this fixed temperature setpoint can be set as the
compensation value.
If temperature compensation is turned off, the probe uses the default value of +25 °C
(+77 °F).
When the probe is installed through a flange and part of the probe and the cable is left
outside the measuring environment, it is possible that temperature conduction from the
probe body and cable outside the measurement environment affects the temperature
compensation and decreases measurement accuracy.
2.4.2. Pressure Compensation
The probe does not have on-board pressure measurement. However, a pressure reading
from an external source can be used as a setpoint value for compensation using Vaisala
Industrial Protocol or Modbus.
If pressure compensation is turned off, the probe uses the default compensation value of
1013 hPa.
2.4.3. Background Gas Compensation
The probe does not have on-board oxygen or relative humidity measurement. However,
oxygen and relative humidity readings from an external source can be used as setpoint
values for compensation using Vaisala Industrial Protocol or Modbus. The default setpoint
values are as follows:
• Oxygen concentration: 0 %O2 or 21 %O2
• Relative humidity: 0 %RH or 50 %RH
If background gas compensations are turned off, the probe uses the value 0 % for both.
In practice, when CO2 is measured at a ppm level, O2 and RH compensations have a very
small effect on the accuracy of the measurement.
13
GMP252 User Guide
M211897EN-A
2.5. Probe Startup
When powered on, the probe starts up within 12 seconds. Measurements from the outputs
(digital and analog) become available during this time but note that they will only reach
specified accuracy after a 2-minute warm-up period. For this reason, you should design your
system so that it does not rely on measurements from the probe during this time. When the
probe is in analog output mode, the probe remains in an error state during the start-up
phase until measurement output becomes available.
Specifically note that the CO2 reading will rise to the correct reading as the sensor’s
infrared emitter achieves operation temperature.
2.6. Analog Output Overrange Behavior
Analog output of the probe has a defined behavior when the values measured by the probe
are outside the scaled analog output range. At first, the output is clipped when the
measurement exceeds a set limit (the measurement continues, but the output does not
change from the clipped value).
When the measurement exceeds the second limit (error limit), the analog output switches to
the error state defined for the output. The table below lists the clipping and error limits and
default error state outputs for the analog voltage and current outputs.
Table 4 Analog Output Overrange Clipping and Error Limits
Output voltage /
current
Clipping Limit
Error Limit
Default Error State
Output
0 ... 5 V
>5%
>10%
0V
0 ... 10 V
>1%
>10%
0V
0 ... 20 mA
>5%
>10%
23 mA
4 ... 20 mA
>5%
>10%
2 mA
The same clipping and error limits are applied when the measured value drops back to the
scaled range: at first the output returns to the clipped value from the error state, and then to
normal output.
Clipping and error state limits differ for 0 ... 10 V and 0 ... 5 V outputs. For 0 ... 10 V output
the limits are 1% and 10%, and for 0 ... 5 V output the limits are 5% and 10%.
14
Chapter 2 – Product Overview
More Information
‣ Analog Output Error State (page 77)
2.6.1. Analog Output Overrange Example
Consider a probe with 0 ... 5 V output, scaled to 0 ... 2000 ppmCO2.
• When the measured CO2 rises above 2000 ppmCO2, the output rises above 5 V.
• The output keeps rising until the measurement is 2100 ppmCO2, at which point the
probe outputs 5.25 V.
• If the CO2 level rises above 2100 ppmCO2, the output still remains at 5.25 V.
• If the CO2 level rises above 2200 ppmCO2, the output enters the error state, which is 0
V for the 0 ... 5 V output.
Output
voltage (V)
0.00
5.25
5.00
Error level
Output clipping limit
In error state at
>2200 ppm
(2000 ppm + 10%)
Clipped at
2100 ppm
(2000 ppm + 5%)
Regular
measurement
Time
Figure 4 Example of Analog Output Overrange Behavior
This example uses output scaled to 0 ... 5 V and 0 ...2000 ppmCO2, error level set to 0 V,
clipping set to 5 % overrange, and error limit set to 10 % overrange. CO2 concentrations
(ppm) are indicated for the clipping point and error limit point.
This overrange and error behavior is specific to the analog output, and does not affect the
readings of the digital outputs.
You can change the analog output overrange behavior using the aover command.
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GMP252 User Guide
M211897EN-A
2.7. Safety
The probe delivered to you has been tested for safety and approved as shipped from the
factory. Note the following precautions:
WARNING! When returning a product for calibration or repair, make sure it has not
been exposed to dangerous contamination, and is safe to handle without special
precautions.
CAUTION! Do not modify the unit. Improper modification can damage the product or
lead to malfunction.
CAUTION! Do not attempt to open the probe body. There are no user serviceable parts
inside the probe body.
2.7.1. ESD Protection
Electrostatic Discharge (ESD) can cause immediate or latent damage to electronic circuits.
Vaisala products are adequately protected against ESD for their intended use. However, it is
possible to damage the product by delivering electrostatic discharges when touching an
exposed contact on the product.
To make sure you are not delivering high static voltages yourself, avoid touching the pins on
the M12 connector.
2.8. Regulatory Compliances
The probe is in conformity with the provisions of the following EU directives:
• EMC Directive
• RoHS Directive
Conformity is shown by compliance with the following standards:
• EN 61326-1: Electrical equipment for measurement, control, and laboratory use – EMC
requirements – Generic environment.
• EN 550022: Information technology equipment – Radio disturbance characteristics –
Limits and methods of measurement.
16
Chapter 3 – Installation
3. Installation
3.1. GMP252 Probe Dimensions
The dimensions are given in millimeters (mm).
130 mm, Ø 25 mm
12 mm
76 mm
42 mm
Figure 5 GMP252 Dimensions
3.2. Recommended Installation
The probe can be installed in an environment with an operating temperature range -40 ...
+60 °C. Make sure the probe is in a location that represents the measurement environment
properly.
The 5-pin male M12 connector on the probe provides an easy plug-in/plug-out connection to
a compatible cable.
3.3. Installation Accessories
The probe can be installed through a surface using the optional flange accessory (Vaisala
product code 243261SP, or attached for example to a wall with the optional clip accessory
(two-clip set, Vaisala product code 243257SP.
More Information
‣ Spare Parts and Accessories (page 82)
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GMP252 User Guide
M211897EN-A
3.3.1. 243261SP Installation Flange
The optional flange accessory is used to install the probe body through a wall or other
surface.
1
2
3
Figure 6 Probe with 243261SP Installation Flange
1
2
3
Four Phillips head screws (included)
Installation flange (diameter 60 mm) with four Ø 4.2 mm screw holes
Gasket ring
Leaving part of the probe body and the cable outside the measurement environment can
cause heat conduction that affects the temperature compensation and measurement
accuracy.
More Information
‣ 243261SP Mounting Flange Dimensions (page 83)
18
Chapter 3 – Installation
3.3.2. 243257SP Mounting Clips
The optional mounting clips (set of two clips) are used to hold the probe in place for
example on a wall or other surface. Each clip base attaches to the installation surface with
one screw (screw hole Ø 4.2 mm).
Ø 4.2 mm
Figure 7 Probe in 243257SP Mounting Clips
3.4. Power Supply
The supply voltage range of the probe is 12 ... 30 VDC with the digital output option. If the
analog output is used, the supply voltage range is 12 ... 30 VDC for voltage output and
20 ... 30 VDC for current output.
Typical power consumption is less than 0.4 W in continuous operation, and the maximum is
0.5 W.
19
GMP252 User Guide
M211897EN-A
3.5. Wiring
3
4
5
2
1
Table 5 M12 Male Connector
Pin#
Function
Note
Cable 223263SP
Wire Colors
1
Power in
With digital output:
12 ... 30 VDC
With voltage output:
12 ... 30 VDC
With current output:
20 ... 30 VDC
Typical average power consumption <0.4 W, maximum
0.5 W
Brown
2
RS-485or voltage
output
Voltage:
0 ... 5 VDC or 0 ... 10 VDC (default analog output scaling)
White
3
GND
4
RS-485 +
or current
output
Current:
0 … 20 mA or 4 ... 20 mA (default analog output scaling)
Black
5
Output control
Connecting pin #5 to GND (pin #3) forces the probe to
analog output mode. If an analog output configuration
has not been selected, default 0...10 VDC and 4...20 mA
scalings are used.
If pin #5 is not connected, the analog or digital output
selected when ordering or set later through
configuration is used.
Gray
Blue
Note that the probe always remains in analog mode when pin #5 is connected to pin #3,
and cannot be switched to digital output in this wiring option.
20
Chapter 4 – Vaisala Industrial Protocol
4. Vaisala Industrial Protocol
4.1. Overview
RS-485 line of the probe provides an implementation of the Vaisala Industrial Protocol that
can be used for service and configuration use, or for interfacing with the system to which
the probe is integrated. The protocol is a plaintext protocol suitable for use both by human
operators and automated systems.
4.2. Serial Interface Settings
Table 6 Default Serial Interface Settings
Property
Description/Value
Baud rate
19200
Parity
None
Data bits
8
Stop bit
1
Flow control
None
4.3. Physical Interface
The physical interface is a non-isolated 2-wire interface. The data lines are RS- 485 D- and
RS-485 D+. Ground is shared with power supply. The connector is a 5-pin male M12.
More Information
‣ Wiring (page 20)
21
GMP252 User Guide
M211897EN-A
4.4. Connecting with a Computer
• Vaisala USB service cable (order code 242659)
• Computer with:
• Windows operating system
• Terminal application (for example PuTTy, available from www.vaisala.com/
software)
• Free USB port
• Driver for Vaisala USB service cable installed (available on the cable installation
media and at www.vaisala.com/software)
The steps below describe how to connect to the probe using the PuTTY terminal application
for Windows and a USB computer connection cable. Connecting with a computer allows you
to configure and troubleshoot your probe using serial line commands.
1. If you have not used the Vaisala USB cable before, install the driver before attempting
to use the cable.
2. Connect the USB serial interface cable between your computer and the M12 connector
of the probe.
3. Start the PuTTY application.
4. Select Connection > Serial & USB and check that the correct COM port is selected in
the Serial or USB line to connect to field. If you are using the PuTTY terminal
application supplied by Vaisala, you can press the USB Finder button to open the
Vaisala USB Instrument Finder program.
5. Check that the other serial settings are correct for your connection, and change if
necessary. Flow control should be set to None unless you have a reason to change it.
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6. Select Terminal. Use the following settings:
• Local Echo: "Force on". This setting ensures that your typing is shown on the session
window.
• Send line ends with line feeds (CR+LF): Selected. This setting ensures that all text
lines remain visible on the session window.
7. Click the Open button to open the connection window and start using the serial line.
If PuTTY is unable to open the serial port you selected, it will show you an error message
instead. If this happens, restart PuTTY and check the settings.
More Information
‣ Serial Interface Settings (page 21)
‣ Installing the Driver for the USB Service Cable (page 23)
4.4.1. Installing the Driver for the USB Service Cable
Before taking the USB service cable into use for the first time, you must install the provided
USB driver on your computer (requires Windows). When installing the driver, you must
accept any security prompts that may appear.
1. Check that the USB service cable is not connected. Disconnect the cable if you have
already connected it.
2. Insert the media that came with the cable, or download the latest driver from
www.vaisala.com/software.
3. Run the USB driver installation program (setup.exe), and accept the installation
defaults. The installation of the driver may take several minutes.
4. After the driver has been installed, connect the USB service cable to a USB port on your
computer. Windows will detect the new device, and use the driver automatically.
5. The installation has reserved a COM port for the cable. Verify the port number, and the
status of the cable, using the Vaisala USB Instrument Finder program that has been
installed in the Windows Start menu. Windows will recognize each individual service
cable as a different device, and reserve a new COM port. Remember to use the correct
port in the settings of your terminal program.
4.5. Accessing Serial Commands from
Modbus or Analog Mode
1. Connect the USB cable to your PC and start the terminal application as instructed in
4.4. Connecting with a Computer (page 22).
2. Start a new terminal session using the default serial settings.
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3. Keep the Enter key pressed down and connect the probe to the USB cable. When the
probe is powered on (connected to your PC with the USB cable), you must send five
carriage returns (Enter key presses) within 0.7 seconds to force the probe to serial
command mode.
4. The probe model information appears in the terminal application when the mode has
been succesfully changed, and Vaisala Industrial Protocol commands are available for
use. You can test the connection with for example the ? command. If the mode change
failed, close the terminal application, disconnect the probe from the USB cable, and
repeat steps 2 and 3.
5. To keep the serial mode in use (forced serial mode access is temporary and switches off
at reset), select a serial output option (stop/run/poll) with the smode command. For
instructions on changing the serial mode, see Table 28 (page 38).
Note that the probe always remains in analog mode when pin #5 is connected to pin #3,
and cannot be switched to digital output in this wiring option.
More Information
‣ Serial Interface Settings (page 21)
‣ Enabling Modbus Mode from Vaisala Industrial Protocol (page 24)
4.6. Enabling Modbus Mode from Vaisala
Industrial Protocol
If you need to switch from Vaisala Industrial Protocol to Modbus mode, you must configure
the following settings:
• Serial line operating mode
• Modbus address
• Serial line settings (baud rate, parity, stop and data bits)
1. Connect the USB cable to your PC and start the terminal application as instructed in
4.4. Connecting with a Computer (page 22).
2. Set the serial mode to Modbus with the smode command: smode modbus
3. Set the Modbus address to 240 with the addr command: addr 240
4. Set the serial line settings to 19200/N/8/2 with the seri command:
seri 19200 N 8 2
5. Power off (disconnect) the probe or reset with the reset command. The new
configuration is available at the next restart.
More Information
‣ Accessing Serial Commands from Modbus or Analog Mode (page 23)
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4.7. Changing From Digital Output to
Analog Output
1. Set up a terminal connection as instructed in 4.4. Connecting with a Computer
(page 22).
2. Change the mode from digital to analog with the smode serial command: smode
analog.
3. Reset the probe (disconnect and reconnect the cable or use the reset serial command)
to power on in analog output mode.
More Information
‣ Accessing Serial Commands from Modbus or Analog Mode (page 23)
4.8. Serial Commands
The notation <cr> refers to the carriage return control character, which you can send in a
terminal application by pressing enter on your keyboard. Before entering commands, send a
<cr> to clear the command buffer.
You can enter the commands in uppercase or lowercase. In the command examples, the
keyboard input by the user is in bold type.
Table 7 (page 25) lists the basic serial commands that are available by default. To access
advanced serial commands (listed in Table 8 (page 26)), enter the command pass 1300.
Table 7 Basic Serial Commands
Command
Description
Device information and status
?
Show probe information.
??
Show probe information (will respond in POLL mode).
errs
Show currently active errors.
help
Show list of currently available serial commands.
snum
Show probe serial number.
system
Show probe firmware information.
time
Show probe operation hours and uptime.
vers
Show probe firmware version.
Serial line output and communication
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Command
Description
close
Close connection to probe (POLL mode)
form [modifier string]
Show or set output format.
intv [0 ... 255 s/min/h]
Set continuous output interval for R command.
open [address]
Open connection to probe in POLL mode.
r
Start the continuous outputting.
s
Stop the continuous outputting.
sdelay [0 ... 255]
Show or set serial line transmission delay in milliseconds.
send
Output a single measurement message.
seri [baud data stop
parity]
Show or set the serial interface settings.
smode [mode]
Show or set startup serial mode: RUN, STOP, or POLL.
Environmental compensation
env
Show or set environmental parameters.
Adjustment information
adate
Show CO2 factory adjustment date.
atext
Show CO2 factory adjustment information.
Other commands
reset
Reset the probe.
pass [1300]
Access advanced serial commands.
Table 8 Advanced Serial Commands
Command
Description
Serial line output and communication
addr [0 … 254]
Show or set probe address.
Analog output
amode
Show or set analog output mode (analog output limits and error level).
aover
Show or set analog output overrange and clipping behavior.
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Command
Description
asel
Show or set analog output parameter and scaling.
Calibration and adjustment
cco2
Adjust CO2 measurement gain and offset.
cdate
Show or set calibration date.
ct
Adjust temperature measurement offset.
ctext
Show or set calibration information.
Environmental compensation
o2cmode
Show or set oxygen compensation mode.
pcmode
Show or set pressure compensation mode.
rhcmode
Show or set humidity compensation mode.
tcmode
Show or set temperature compensation mode.
Other commands
frestore
Restore probe to factory settings.
4.9. Device Information and Status
Table 9 ? Command
Syntax
Description
?<cr>
Show listing of device information.
??<cr>
Show listing of device information even if device is in
poll mode and connection has not been opened
using the open command.
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Description
Example:
?
Device : GMP25x
Copyright : Copyright (c) Vaisala Oyj 2016. All rights
reserved.
SW Name : GMP25x
SW version : 1.0.0
SNUM : GMP233_5_18
SSNUM : S1234567
CBNUM : c1234567
Calibrated : 20160504 @ Vaisala/R&D
Address : 0
Smode : STOP
Table 10 Errs Command
Syntax
Description
errs<cr>
Show active error(s). For a list of possible errors and
their remedies, see 8.2. Error Messages (page 75).
Example (no active errors):
errs
NO CRITICAL ERRORS
NO ERRORS
NO WARNINGS
STATUS NORMAL
Table 11 Help Command
Syntax
Description
help<cr>
Show list of currently available serial commands.
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Syntax
Description
Example (showing a list of the basic commands):
help
ADATE
ADDR
ATEXT
CLOSE
ENV
ERRS
FORM
HELP
INTV
PASS
RR
ESET
RX
SDELAY
SEND
SENDX
SERI
SMODE
SNUM
SYSTEM
UNIQID
TIME
VERS
Table 12 Snum command
Syntax
Description
snum<cr>
Show serial number of the probe.
Example:
snum
SNUM : M0220028
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Table 13 System Command
Syntax
Description
system<cr>
Show probe firmware information.
Example:
system
Device Name : GMP25x
SW Name : GMP25x
SW version : 1.0.0
Operating system : TSFOS1.0
Table 14 Time Command
Syntax
Description
time<cr>
Show how long the probe has been in operation
since the last startup or reset.
The operation counter is in format hh:mm:ss.
Example:
time
Time : 01:41:24
Table 15 Vers Command
Syntax
Description
vers<cr>
Show firmware version of the probe.
Example:
vers
SW version : 1.0.0
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4.10. Serial Line Output and
Communication
Table 16 Addr Command
Syntax
Description
addr<cr>
Show current device address. Addresses are required
for POLL mode.
addr [aaa]<cr>
Set new device address. aaa = address, 0 ... 254
(default = 0)
Example (shows 0 as current address, enter 5 as the new address):
addr
Address : 0
addr 5
Address : 5
Table 17 Close Command
Syntax
Description
close<cr>
Close the connection that was opened with the open
command.
Example:
close
line closed
Table 18 Form Command
Syntax
Description
form<cr>
Show the currently used measurement format.
form /<cr>
Reset measurement format to default.
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Syntax
Description
form [sss]<cr>
Set a new measurement format.
sss = String consisting of modifiers and
abbreviations for measured parameters.
See Table 19 on the facing page and Table 20 on the
facing page.
Maximum length is 150 characters. Maximum length
may be shorter when text strings are used.
Example (show currently used measurement format (default format shown here)):
form
6.0 "CO2=" CO2 " " U3 #r #n
Output example (continuous output from RUN mode):
CO2= 452 ppm
Example (set output format as %CO2):
form 3.1 "CO2=" CO2% " " U4 #r #n
OK
Output example (continuous output from RUN mode):
CO2= 5.1 %CO2
CO2= 5.1 %CO2
CO2= 5.0 %CO2
...
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Syntax
Description
Example (set output format as CO2 ppm with Modulus-65536 checksum):
form 6.0 "CO2=" CO2 " " U3 " " CS4 #r #n
OK
Output example (continuous output from RUN mode):
CO2= 3563 ppm 9F
CO2= 3562 ppm 9E
CO2= 3559 ppm A4
...
Example (set output format as CO2 ppm, with start of text (ASCII character 002) and end of text (003) ASCII
codes, and without line feed and carriage return at the end):
form #002 6.0 "CO2=" CO2 " " U3 #003
OK
Output example (continuous output from RUN mode, ASCII codes not visible here):
CO2= 866 ppm CO2= 866 ppm CO2= 867 ppm CO2= 867 ppm
CO2= 867 ppm CO2= 868 ppm CO2= 868 ppm CO2= 869 ppm
...
Table 19 Output Parameters for Form Command
Output Parameter
Abbreviation in Form Command
Carbon dioxide in ppm
co2
Carbon dioxide in percent
co2%
Currently used temperature compensation value
tcomp
Currently used pressure compensation value
pcomp
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Output Parameter
Abbreviation in Form Command
Currently used oxygen concentration compensation
value
o2comp
Currently used relative humidity compensation value
rhcomp
Table 20 Modifiers for Form Command
Modifier
Description
x.y
Length modifier (number of digits and decimal
places).
#t
Tabulator.
#r
Carriage-return.
#n
Line feed.
""
String constant, length 1 ... 15 characters.
#xxx
ASCII code value (decimal) of a special character; for
example, #027 for ESC.
addr
Probe address (0 ... 254).
sn
Probe serial number.
time
Cumulative operating hours of the probe.
ux
Name of the measurement unit using x number of
characters. For example, u3 shows the name of the
measurement unit with three characters.
cs4
Modulus-65536 checksum of message sent so far,
ASCII encoded hexadecimal notation.
csx
NMEA xor-checksum of message sent so far, ASCII
encoded hexadecimal notation.
You can also use the backslash character \ instead of the hash character #.
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Table 21 Intv Command
Syntax
Description
intv<cr>
Show the output interval of the automatically
repeating measurement messages (r command and
run mode).
intv [iii uuu]<cr>
Set the output interval.
iii = interval, range 0 ... 255.
u = unit for interval setting:
• s = seconds
• min = minutes
• h = hours
If you set the interval to 0, the output messages are
output as quickly as they are generated, without
additional delay.
Example:
intv 5 s
Output interval: 5 S
Table 22 Open Command
Syntax
Description
open [aaa]<cr>
Open a connection to a device at the specified
address. Required when device is in poll mode.
aaa = address, range 0 ... 254.
Example (target probe in POLL mode, with address 52):
open 52
GMP25x: 52 Opened for operator commands
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Table 23 R Command
Syntax
Description
r<cr>
Start the continuous outputting of measurement
values as an ASCII text string to the serial line. The
probe keeps outputting measurement messages at
the interval that has been set with the intv
command until stopped with the s command.
Example:
r
CO2=
CO2=
CO2=
CO2=
CO2=
...
1024
1024
1028
1026
1028
ppm
ppm
ppm
ppm
ppm
Table 24 S Command
Syntax
Description
s<cr>
Stop the continuous outputting that was started with
the r command.
Example:
...
CO2= 658 ppm
CO2= 654 ppm
CO2= 655 ppm
s
Table 25 Sdelay Command
Syntax
Description
sdelay<cr>
Show serial line transmission delay in milliseconds.
sdelay [delay]<cr>
Set a new serial line transmission delay.
delay = Serial line delay, range 0 … 255
(milliseconds).
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Chapter 4 – Vaisala Industrial Protocol
Syntax
Description
Example (set delay to 50 milliseconds):
sdelay 50
COM transmit delay : 50
Table 26 Send Command
Syntax
Description
send<cr>
Output a single measurement message.
send [aaa]<cr>
Output a single measurement message from a device
in poll mode.
aaa = address of the probe, range range 0 ... 254
Example:
send
CO2= 1422 ppm
Example (target probe in POLL mode, with address 52):
send 52
CO2= 458 ppm
Table 27 Seri Command
Syntax
Description
seri<cr>
Show current serial line settings.
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Syntax
Description
seri [b p d s]<cr>
Set new serial line settings. The new settings will be
taken into use when the probe is reset or powered
up.
b = baud rate (9600, 19200, or 38400)
p = parity
• n = none
• e = even
• o = odd
d = data bits (7 or 8)
s = stop bits (1 or 2)
For Modbus, baud rate must be 9600 ... 38400 and
parity must be none.
Example (show current settings):
seri
Com1
Com1
Com1
Com1
Baud rate : 19200
Parity : N
Data bits : 8
Stop bits : 1
Example (set serial line to 9600 baud, even, 7 data bits, and 1 stop bit, and reset the probe to take the new
settings in use):
seri 9600 e 7 1
OK
seri
Com1 Baud rate : 9600
Com1 Parity : E
Com1 Data bits : 7
Com1 Stop bits : 1
reset
GMP25x 1.0.0
Table 28 Smode Command
Syntax
Description
smode<cr>
Show current start-up operating mode of the serial
line, and prompt to enter new mode.
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Syntax
Description
smode [mode]<cr>
Set serial line start-up operating mode. New mode is
taken into use when the device is reset or powered
up.
Available modes:
stop = No automatic output. All commands
available. Default mode.
run = Automatic output of measurement messages.
You can stop the output with the s command, and
recontinue with the r command.
poll = No automatic output. Will respond to
addressed send command and ?? command. You
can use other commands after opening a connection
using an addressed open command. Use with RS485 buses where multiple probes can share the same
line.
modbus = Serial line communication uses the
Modbus protocol. Serial line commands (Vaisala
Industrial Protocol) are not accessible in the Modbus
mode.
analog = Switches the probe from digital output to
analog output (active after probe reset). Serial line
commands are not accessible in the analog mode.
Example (set serial mode to "poll"):
smode poll
Serial mode : POLL
4.11. Analog Output
Table 29 Amode Command
Syntax
Description
amode [channel]<cr>
Show currently set analog output limits and error
level.
channel = Analog output channel
• 1 = voltage output (V)
• 2 = current output (mA)
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Syntax
Description
amode [channel lo_value hi_value
error_value]<cr>
Set new analog output limits and error output value.
channel = Analog output channel
• 1 = voltage output (V)
• 2 = current output (mA)
lo_value = Low limit of the channel.
hi_value = High limit of the channel.
error_value = Error value of the channel.
Example (show current configuration):
pass 1300
amode 1
Aout 1 range (V) : 0.00 ... 10.00 (error : 0.00)
amode 2
Aout 2 range (mA) : 4.00 ... 20.00 (error : 2.00)
Example (set channel 1 to 0 … 5 V, and error output to 0.0 V; set channel 2 to 0 ... 20 mA, and error output to
23 mA):
amode 1 0 5 0.0
Aout 1 range (V) : 0.00 ... 5.00 (error : 0.00)
amode 2 0 20 23
Aout 2 range (mA) : 0.00 ... 20.00 (error : 23.00)
Table 30 Aover Command
Syntax
Description
aover [channel<cr>
Show the behavior of the analog output when the
measured value is outside the scaled output range.
channel = Analog output channel
• 1 = voltage output (V)
• 2 = current output (mA)
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Syntax
Description
aover [channel clipping error_
limit]<cr>
Set the behavior of the analog output when the
measured value is outside the scaled output range.
channel = Analog output channel
• 1 = voltage output (V)
• 2 = current output (mA)
clipping = Output margin (%) at which the output
is clipped.
error_limit = Measurement value margin (%) at
which the output of the channel goes into the error
state. The current or voltage output of the error state
is defined using the amode command.
Example (view currently set analog output overrange behavior on channel 1):
pass 1300
aover 1
Aout 1 clipping :5.00 %
Aout 1 error limit :10.00 %
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Description
Example (for channel 1):
1. View currently set analog output scaling (asel command), limits and error level (amode command),
and overrange behavior (aover command):
pass 1300
asel 1
Aout 1 quantity : CO2(0 ... 2000)
amode 1
Aout 1 range (V) : 0.00 ... 5.00 (error : 0.00)
aover 1
Aout 1 clipping :1.00 %
Aout 1 error limit :5.00 %
2. Set analog output overrange clipping to 5 % and error limit to 10 %:
aover 1 5 10
Aout 1 clipping : 5.00 %
Aout 1 error limit : 10.00 %
The analog output now behaves like this:
• Clipping is now set to 5.00 %, meaning the voltage output is allowed to vary between 0 ... 5.25 V. The
analog channel will output the measurement for 0 ... 2100 ppmCO2, but range 0 ... 5 V remains scaled to
0 ... 2000 ppmCO2.
• Error limit is 10 %, which means the output will show the error state (0 V) when the measured CO2
concentration is 10 % outside the scaled output range. With the settings above, this will happen if the
measured CO2 concentration is outside range 0 ... 2200 ppmCO2.
• The voltage output will never be above 5.25 V because of clipping: the voltage output is clipped when
the output reaches 5.25 V, and if the measured CO2 concentration keeps rising above 2200 ppmCO2,
the output jumps directly to the error state 0 V.
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Syntax
Description
Output
voltage (V)
0.00
5.25
5.00
Error level
Output clipping limit
In error state at
>2200 ppm
(2000 ppm + 10%)
Clipped at
2100 ppm
(2000 ppm + 5%)
Regular
measurement
Time
Figure 8 Example of analog output overrange behavior
The example shown above uses output scaled to 0 ... 5 V and 0 ... 2000 ppmCO2, has error level set to 0 V,
clipping set to 5 % overrange, and error limit set to 10 % overrange. CO2 concentrations (ppm) are indicated
for the clipping point and error limit point
Table 31 Asel Command
Syntax
Description
asel [channel]<cr>
Show the parameter and scaling of the analog
output in ppm.
channel = Analog output channel
• 1 = voltage output (V)
• 2 = current output (mA)
asel [channel] [parameter lowlimit
highlimit]<cr>
Set the parameter and scaling of the analog output.
channel = Analog output channel
parameter = Parameter that is output on analog
channel. The only parameter available is CO2 (in
ppm).
lowlimit = Lower limit of channel scaling in ppm.
Minimum value is -1000000 ppm (= - 100 %).
highlimit = High limit of channel scaling in ppm.
Maximum value is 1000000 ppm (= 100 %).
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Description
Example (for channel 1, show the currently set analog output parameter and scaling):
pass 1300
asel 1
Aout 1 quantity : CO2(0 ... 10000 ppm)
Example (for channel 1, set scaling to 0 ... 4000 ppmCO2):
pass 1300
asel 1 co2 0 4000
Aout 1 quantity : CO2(0 ... 4000 ppm)
4.12. Calibration and Adjustment
CAUTION! Before using the calibration and adjustment commands, read through 7.3.
Calibration and Adjustment (page 70). Make sure that the environmental
compensation settings of the probe are properly set for your calibration environment;
see 2.4. Environmental Compensation (page 12).
Table 32 Adate Command
Syntax
Description
adate<cr>
Show CO2 factory adjustment date.
Example:
adate
Adjustment date : 20150420
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Table 33 Atext Command
Syntax
Description
atext<cr>
Show CO2 factory adjustment information.
Example:
atext
Adjusted at Vaisala/Helsinki
Table 34 Cdate Command
Syntax
Description
cdate<cr>
Show calibration date.
cdate [yyyymmdd]<cr>
Set a new calibration date.
yyyymmdd = Year (yyyy), month (mm) and day (dd)
of calibration
Example:
pass 1300
cdate
Calibration date : 20150220
Example (set a new calibration date to June 30, 2015):
cdate 20150630
Calibration date : 20150630
Table 35 Ctext Command
Syntax
Description
ctext<cr>
Show calibration information text.
ctext [text]<cr>
Set a new calibration information text to be shown
after the automatic text "Calibrated at".
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Description
Example:
pass 1300
ctext
Calibrated at 500 ppm in lab
Example (set a new information text):
ctext 0/1000 by NN
Calibrated at 0/1000 ppm by NN
Table 36 CCO2 Command
Syntax
Description
cco2<cr>
Show current user adjustment status.
cco2 -lo [co2]<cr>
cco2 -hi [co2]<cr>
Perform a 1-point (only either low or high
concentration) or 2-point (both low and high
concentrations) calibration and adjustment.
-lo = Adjustment at low concentration (under 1000
ppmCO2)
-hi = Adjustment at high concentration (over 2000
ppmCO2)
co2 = CO2 concentration reference in ppm
cco2 -save<cr>
Save the currently entered adjustments.
Successfully saving the adjustment clears the
calibration date (cdate command) and calibration
text (ctext command) that have been stored in the
probe. Use those commands to enter a new
calibration date and text.
cco2 -cancel<cr>
Cancel currently entered adjustments.
cco2 -reset<cr>
Clear user adjustments.
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Syntax
Description
Example (show current user adjustment status; no adjustment done):
pass 1300
cco2
1.Ref. point low 0
1.Meas. point low 0
2.Ref. point high 3000
2.Meas. point high 3000
Gain : 1.0000
Offset : 0.0000
Example (perform a 1-point calibration):
1. Let the probe stabilize in the desired CO2 concentration (here: 500 ppmCO2).
2. Enter the calibration commands:
pass 1300
cco2 -lo 500
OK
cco2 -save
OK
3. Enter a new calibration date and information text:
cdate 20160325
Calibration date : 20160325
ctext 500 ppm in lab
Calibrated at 500 ppm in lab
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Description
Example (perform 2-point calibration):
1. Let the probe stabilize in the desired low CO2 concentration (here: 200 ppmCO2).
2. Enter the calibration commands:
pass 1300
cco2 -lo 200
OK
cco2 -save
OK
3. Let the probe stabilize in the desired high CO2 concentration (here: 3000 ppmCO2).
4. Enter the calibration commands:
pass 1300
cco2 -hi 3000
OK
cco2 -save
OK
5. Enter a new calibration date and information text:
pass 1300
cdate 20160425
Calibration date : 20160425
ctext 200/3000 ppm
Calibrated at 200/3000 ppm
4.13. Environmental Compensation
Commands
To apply an accurate relative humidity compensation, the temperature and pressure
compensation configurations must also match your measurement environment. See the
rhcmode, tcmode and pcmode commands for instructions on enabling compensation
configuration, and env command for instructions on setting a compensation value.
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For more information on environmental compensation and the default (neutral)
compensation values used for disabled compensations, see 2.4. Environmental
Compensation (page 12)
Table 37 Env Command
Syntax
Description
env<cr>
Show current compensation values.
Before using this command, you must enable
environmental compensation using the following
commands:
•
•
•
•
env [temp | pres | oxy | hum]
[value]<cr>
o2cmode [on]
pcmode [on]
rhcmode [on]
tcmode [on | measured]
Set new permanent compensation values and store
them in eeprom.
Eeprom:
• Non-volatile memory, values retained during
power off.
• Number of writes is limited to 30000 cycles by
memory implementation.
• Must only be used for writing permanent
values, to avoid wearing out the eeprom.
temp = Compensation temperature. Range -40 ...
+100 °C.
pres = Compensation pressure. Range 500 ... 1100
hPa.
oxy = Oxygen content of background gas. Range
0 ... 100 %.
hum = Relative humidity of background gas. Range
0 ... 100 %.
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Syntax
Description
env [xtemp | xpres | xoxy | xhum]
[value]<cr>
Set new compensation values and store them in
RAM.
RAM: n Volatile memory that loses the values when
probe is reset, and where values are loaded from
non-volatile memory at startup. n Must be used for
continuously updated values.
xtemp = Compensation temperature stored in RAM.
Range -40 ... 100 °C.
xpres = Compensation pressure stored in RAM.
Range 500 ... 1100 hPa.
xoxy = Oxygen content of background gas stored
in RAM. Range 0 ... 100 %.
xhum = Relative humidity of background gas stored
in RAM. Range 0 ... 100 %.
Note: If temperature
compensation is configured to
use an internally measured value
(tcmode is set to measured), it
will continuously update the
value in RAM, overriding any
temperature value that is written
to RAM with the ENV command.
Example (Show current compensation values; all compensations are enabled. Note that temperature
compensation is in "measured" mode, so the value in use is constantly changing):
env
In eeprom:
Temperature (C) : 8.00
Pressure (hPa) : 1013.00
Oxygen (%O2) : 21.00
Humidity (%RH) : 30.00
In use:
Temperature (C) : 4.90
Pressure (hPa) : 1013.00
Oxygen (%O2) : 19.70
Humidity (%RH) : 27.00
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Syntax
Description
Example (set temperature compensation to setpoint mode, and change temperature setpoint value to
5.00 °C in RAM):
pass 1300
tcmode on
T COMP MODE : ON
env xtemp 5.00
In eeprom:
Temperature (C) : 8.00
Pressure (hPa) : 1013.00
Oxygen (%O2) : 21.00
Humidity (%RH) : 30.000
In use:
Temperature (C) : 5.00
Pressure (hPa) : 1013.00
Oxygen (%O2) : 21.00
Humidity (%RH) : 30.00
Table 38 O2cmode Command
Syntax
Description
o2cmode<cr>
Check current oxygen compensation mode.
Possible modes:
• on = Compensation enabled using setpoint
value.
• off = Compensation disabled, default
(neutral) value used: see 2.4. Environmental
Compensation (page 12)
o2cmode [on | off]<cr>
Change oxygen compensation mode (on or off).
Example (check oxygen compensation mode; oxygen compensation is disabled, a neutral value is used):
pass 1300
o2cmode
O2 COMP MODE : OFF
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Syntax
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Description
Example (enable oxygen compensation):
pass 1300
o2cmode on
O2 COMP MODE : ON
Table 39 Pcmode Command
Syntax
Description
pcmode<cr>
Check current pressure compensation mode.
Possible modes:
• on = Compensation enabled using setpoint
value.
• off = Compensation disabled, default
(neutral) value used: see 2.4. Environmental
Compensation (page 12).
pcmode [on | off]<cr>
Change pressure compensation mode (on or off).
Example (check pressure compensation mode; pressure compensation is enabled using a setpoint value):
pass 1300
pcmode
P COMP MODE : ON
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Table 40 Rhcmode Command
Syntax
Description
rhcmode<cr>
Check current relative humidity compensation mode.
Possible modes:
• on = Compensation enabled using setpoint
value.
• off = Compensation disabled, default
(neutral) value used: see 2.4. Environmental
Compensation (page 12).
To apply an accurate relative
humidity compensation, make
sure that the temperature
compensation and pressure
compensation configurations
also match the measurement
environment.
rhcmode [on | off]<cr>
Change relative humidity compensation mode (on or
off).
Example (check relative humidity compensation mode; relative humidity compensation is disabled, a neutral
value is used):
pass 1300
rhcmode
RH COMP MODE : OFF
Example (enable temperature, pressure and relative humidity compensation using setpoint values):
pass 1300
tcmode on
T COMP MODE : ON
pcmode on
P COMP MODE : ON
rhcmode on
RH COMP MODE : ON
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Table 41 Tcmode Command
Syntax
Description
tcmode<cr>
Check current temperature compensation mode.
Possible modes:
• on = Compensation enabled using setpoint
value.
• off = Compensation disabled, default
(neutral) value used: see 2.4. Environmental
Compensation (page 12)
• measured = Compensation enabled using
internal measurement.
tcmode [on | off | measured]<cr>
Change temperature compensation mode (on, off
or measured).
Example (check temperature compensation mode; temperature compensation is enabled using a setpoint
value):
pass 1300
tcmode
T COMP MODE : ON
Example (change temperature compensation to use internal measurement):
pass 1300
tcmode measured
T COMP MODE : MEASURED
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4.14. Other Commands
Table 42 Frestore Command
Syntax
Description
frestore<cr>
Restore the probe to its factory configuration. All
user settings and user calibration parameters will be
lost.
After using the frestore
command, reset the probe using
the reset command.
Example (restore the factory settings and reset the probe):
pass 1300
frestore
Parameters restored to factory defaults
reset
GMP25x 1.0.0
Table 43 Pass Command
Syntax
Description
pass [code]<cr>
Access advanced serial commands.
Advanced commands can be used until the next
reset.
code = Code for enabling advanced commands
(1300).
Example:
pass 1300
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Table 44 Reset Command
Syntax
Description
reset<cr>
Reset the probe. The probe will restart as if it had
just been powered on.
Example:
reset
GMP25x 1.0.0
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Chapter 5 – Modbus
5. Modbus
The probe can be accessed using the Modbus serial communication protocol. The supported
Modbus variant is Modbus RTU (Serial Modbus) over RS-485 interface.
For instructions on enabling the Modbus mode when you are using the probe with Vaisala
Industrial Protocol, see 4.6. Enabling Modbus Mode from Vaisala Industrial Protocol
(page 24).
For instructions on switching to Vaisala Industrial Protocol when the probe is in Modbus
mode, see 4.5. Accessing Serial Commands from Modbus or Analog Mode (page 23).
The pre-configured default Modbus serial settings are presented in the following table.
Table 45 Default Modbus Serial Communication Settings
Description
Default Value
Serial bit rate
19200
Parity
N
Number of data bits
8
Number of stop bits
2
Modbus device address
240
More Information
‣ Function Codes (page 85)
‣ Modbus Registers (page 85)
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Chapter 6 – Operating with MI70 Indicator
6. Operating with MI70
Indicator
6.1. Overview of MI70 Support
The probe is compatible with instruments that utilize the MI70 indicator, for example the
GM70 Hand-Held Carbon Dioxide Meter. The MI70 indicator is a convenient service tool for
viewing the measurement readings, adjusting the environmental compensation settings, and
performing calibration and one-point adjustment.
When MI70 is used with GMP252, it is recommended to use the rechargeable battery pack
instead of alkaline batteries due to the relatively high power usage in CO2 measurement.
6.2. Basic Display
Figure 9 MI70 Basic Display
1
2
3
4
5
Measured parameter and compensations
(up to three items on display
simultaneously).
Battery indicator. Shows current status
(charge) of the battery.
Function key Graphic shows the readings
as a curve.
Function key Hold/Save freezes the
display and you can save the reading in
the MI70 memory.
Function key Record is a quick access to
the Recording/Viewing menu.
You can change the shown items in Main menu > Display > Quantities and units.
You can change the default function key shortcuts (Graphic, Hold/Save, Record) to other
menus or functions in Main menu > Settings > User interface > Program shortcut keys.
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6.3. Graphical Display
The graphical display shows you the measurements as a curve. From the curve you can
examine the data trend and history of the last minutes.
To open the graphical display, select Graphic in the basic display or select Main menu >
Display > Graphic history > Show.
To zoom in and out, press the up/down arrow keys.
To move back and forward in the timeline, use the left/right arrow keys.
6.4. Main Menu
To open the main menu:
1. Go to the basic display.
2. Press any arrow key, then select OPEN. In the main menu, you can configure the MI70
settings and basic display options, view information about the probe, access recordings
and clear the memory, set alarms, start adjustments, and use the analog output option
of the MI70 indicator.
6.5. Connecting Probe to MI70 Indicator
1. If the probe is installed permanently into a device (for example, an incubator or a
chamber), disconnect the probe from the connector.
2. If the MI70 indicator is on, turn it off.
3. Connect the probe to the MI70 indicator using the MI70 connection cable (Vaisala order
code: CBL210472).
4. Turn on the MI70 indicator (time and date are requested at first startup). MI70 detects
the probe and proceeds to show the measurement screen. The parameters measured
by probe will start to show valid measurement results after a few seconds.
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6.6. MI70 Indicator Parts
1
Figure 10 MI70 Indicator Parts
1
2
2
3
Up/down
button
Right button
Left button
3
4
5
4
5
6
6
Charger socket
Function buttons. The functions change
according to what you are doing with the
indicator.
Arrow buttons:
Move up and down in a
menu
Enter a sub-menu
Return to the previous
menu level
Power On/Off button
Battery compartment at the back of the
indicator
Port I and port II for probe or hand-held
instrument connection
To open menus, press an arrow button and then press the shortcut buttons. To activate a
function shown above the shortcut button, press the shortcut button. To navigate in the
menus, press arrow buttons.
6.7. Holding and Saving the Display
With the Hold/Save function, you can freeze a certain display reading. This reading can be
saved in the MI70 memory and it will be available even after MI70 is disconnected from the
transmitter.
1. In the basic display, select Hold/Save. Alternatively, select Main menu > Display >
Hold/Save display > Hold.
2. Press Save.
3. To view the saved display, go to basic display and select Record > View recorded data.
Alternatively, select Main menu > Recording/Viewing > View recorded data.
A list of saved displays and data recordings appears. The icons on the left of the date
and time indicate whether the file is a saved display or a longer recording of data:
Saved display
Data recording
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4. Select the saved display based on date and time by pressing the right arrow key.
6.8. Recording Data
With MI70, you can record transmitter measurement data over a certain period at chosen
intervals. These recordings are saved in MI70 memory and are available even after MI70 is
disconnected from the transmitter.
Starting and Stopping the Recording
You can record the measurement of the parameters that are currently shown on the MI70
basic display. You can change the shown parameters in Main menu > Display > Quantities
and units.
1. In the basic display, select Record > Record data Alternatively, select Main menu >
Recording/Viewing > Record data.
2. If needed, change the interval and duration of the recording in the RECORD DATA view.
The measurement intervals and maximum recording times are shown in Table 46 below.
If you set the duration to "Memory full", the recoding will continue until the MI70 memory
is full or until you stop the recording manually. The maximum recording time will be shown
when you start the recording.
3. Select Start/Stop recording > Start.
The recording will continue until the duration has passed or until you stop the recording
manually.
You can switch the MI70 off during recording to save battery. A progress bar is shown
on the display every 10 seconds (or all the time, if charger is connected). The progress
bar shows the amount of recorded data.
CAUTION! Do not disconnect the probe when the data recording is on, even if the
indicator is off. This may cause loss of recorded data.
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Chapter 6 – Operating with MI70 Indicator
4. To stop the recording manually, in the basic display select Record > Record dataStart/
stop recordingStop.
Recording Interval
Maximum Recording Time (memory full)
1 Parameter
2 Parameters
3 Parameters
1s
45 min
22 min
15 min
5s
3h
113 min
75 min
15 s
11 h
5h
3h
30 s
22 h
11 h
7h
1 min
45 h
22 h
15 h
5 min
9 days
4 days
3 days
15 min
28 days
14 days
9 days
30 min
56 days
28 days
18 days
1h
113 days
56 days
37 days
3h
339 days
169 days
112 days
12 h
1359 days
678 days
451 days
6.9. Changing Environmental
Compensation Settings with MI70
Indicator
You can see the compensation values that are currently used by the probe by selecting them
as display quantities from Main menu > Display > Quantities and Units. The quantities are
as follows:
•
•
•
•
Tcomp: currently active temperature compensation value.
Pcomp: currently active pressure compensation value.
Ocomp: currently active oxygen concentration compensation value.
Hcomp: currently active relative humidity compensation value.
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Figure 11 CO2 Reading with Tcomp and Pcomp on MI70 Screen
You can change the compensation settings from Main menu > Settings > Measurement
settings. For more information about the possible settings and their meaning, see 2.4.
Environmental Compensation (page 12).
Figure 12 Probe Compensation Settings on MI70 Screen
When you turn a compensation off, the probe still shows a value for the corresponding
display quantity (for example, Pcomp shows 1013.2 hPa). This is the default compensation
value that is mathematically neutral for the probe’s internal compensation model.
6.10. Calibration and Adjustment with
MI70 Indicator
Before using the MI70 indicator for calibration and adjustment, read the instructions in 7.3.
Calibration and Adjustment (page 70). Make sure that the environmental compensation
settings of the probe are properly set for your calibration environment; see 6.9. Changing
Environmental Compensation Settings with MI70 Indicator (page 63).
When two probes are connected to the MI70 indicator, MI70 uses Roman numerals “I” and
“II” to indicate which port the parameter or function in question is connected to.
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Chapter 6 – Operating with MI70 Indicator
6.10.1. 1-Point Adjustment with an MI70-Compatible Reference
Probe
1. Connect the GMP252 probe to Port I of the MI70 indicator.
2. Connect the calibrated reference probe to Port II. Make sure the reference probe is in
the same environment as GMP252's sensor.
3. If you are using the calibration adapter to feed a calibration gas to GMP252, you must
feed the same gas to the reference probe as well. Refer to the documentation of your
reference probe on how to do this and what accessories you need.
4. Turn on the MI70 indicator.
5. Start the adjustment sequence from Main menu > Functions > Adjustments.
6. MI70 notifies you that automatic power off is disabled during adjustment mode, press
OK to acknowledge.
7. To proceed with the adjustment, select the CO2(I) parameter in the Select Quantity
screen. In the Select Quantity screen you can also view the currently used
compensation values, and the Last adjustment date information. You can update the
date and text using the CDATE and CTEXT commands on the serial line.
8. You may be prompted to check the environmental settings of the reference probe
before proceeding. Press Yes to check the settings and Exit when you have checked
and corrected the settings.
9. The adjustment mode is now active, and you can see the measured CO2 readings and
their difference on the screen. Allow the measurement to stabilize. To proceed with the
adjustment, press Adjust.
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10. Select To same as CO2(II).
11. You will be prompted to confirm you want to adjust: select Yes.
12. If the adjustment is successful, MI70 will show the text Adjustment Done, after which
you will return to the adjustment mode. At this point you can press Back and Exit to
leave the adjustment mode. The adjustment is now completed. If the adjustment
cannot be applied, MI70 will show the text Cannot adjust, possibly followed by a text
stating the reason. A possible reason for an adjustment failure is attempting to apply a
very large correction to the reading.
6.10.2. 1-Point Adjustment with a Reference Gas
1. Connect GMP252 to Port I of the MI70 indicator.
2. Feed a calibration gas to the GMP252 using the calibration adapter accessory (Vaisala
order code: DRW244827SP). If you are using ambient air as the calibration gas, you
must have a reference meter in the same environment to verify the CO2 concentration.
3. Turn on the MI70 indicator.
4. Start the adjustment sequence from Main menu > Functions > Adjustments.
5. MI70 notifies you that automatic power off is disabled during adjustment mode, press
OK to acknowledge.
6. Select the CO2 parameter when prompted.
7. You may be prompted to check the environmental settings of the reference probe
before proceeding. Press Yes to check the settings and Exit when you have checked
and corrected the settings.
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Chapter 6 – Operating with MI70 Indicator
8. The adjustment mode is now active, and you can see the measured CO2 reading on the
screen. To proceed with the adjustment, press Adjust.
9. Select 1-point adjustment.
10. You will be prompted if you really want to adjust. Select Yes.
11. You are now in the 1-point adjustment screen. Allow the measurement to stabilize and
press Ready.
12. Enter the CO2 concentration of the reference gas and press OK.
13. You will be prompted if you really want to adjust. Select Yes.
14. If the adjustment is successful, MI70 will show the text Adjustment Done, after which
you will return to the adjustment mode. At this point you can press Back and Exit to
leave the adjustment mode. The adjustment is now completed. If the adjustment
cannot be applied, MI70 will show the text Cannot adjust, possibly followed by a text
stating the reason. A possible reason for an adjustment failure is attempting to apply a
very large correction to the reading.
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Chapter 7 – Maintenance
7. Maintenance
7.1. Cleaning
You can clean the probe body by wiping it with a moist cloth. Standard cleaning agents can
be used.
Note the following precautions when cleaning:
• Do not immerse the probe in liquid to clean it.
• Be careful not to block the filter when cleaning the probe.The optional sintered PTFE
filter is especially sensitive to blockage.
• When changing the filter, you can use clean instrument air to gently blow any loose dirt
and filter material from the sensor. Do not attempt to clean the optical surfaces in any
other manner.
7.1.1. Chemical Tolerance
The following chemicals can be used to clean the probe:
• H2O2 (2000 ppm), non-condensing
• Alcohol-based cleaning agents such as ethanol and IPA (70 % Isopropyl Alcohol, 30 %
water)
• Acetone
• Acetic acid
Avoid exposing the probe to chemicals for unnecessarily long periods of time. Do not
immerse the probe in a chemical, and wipe chemicals off the probe after cleaning.
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7.2. Changing the Filter
Change the filter to a new one if it shows visible signs of contamination or dirt. When
changing the filter, use clean gloves to avoid blocking the pores of the new filter.
Figure 13 Opening the Filter
CAUTION! When changing the filter, you can use clean instrument air to gently blow
any loose dirt and filter material from the sensor. Do not attempt to clean the optical
surfaces in any other manner.
7.3. Calibration and Adjustment
Calibrate and adjust the CO2 measurement of the probe as needed. Before starting, read
through this section completely so that you are aware of your options, and the main factors
that affect the result.
Performing an accurate calibration and adjustment takes some time and preparation.
Instead of doing it yourself, you can also have a Vaisala Service Center calibrate and adjust
your probe.
Calibration means comparing the measurement output of the device to a known
reference, such as a known environment in a calibration chamber or the output of a
reference instrument. Correcting the reading of the device so that is measures accurately
is referred to as adjustment.
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7.3.1. Calibration Setup
Using Hand-Held Meter as Reference
You can perform a 1-point calibration using a hand-held meter as a reference. You will need a
calibrated reference instrument to compare against, for example a GM70 hand-held meter
with a calibrated GMP222 probe.
With the probe and the reference instrument in the same space, allow the measurement to
stabilize before comparing the readings. Try to provide as stable an environment as you can
during this time. Avoid working around the probe and reference instrument during this time.
Using Calibration Gas as Reference
There are two easy ways to use a calibration gas as a reference:
• You can supply the gas to the probe using the calibration adapter accessory (Vaisala
order code DRW244827SP). Gas flow should be in the range 0.5 ... 1.1 l/min,
recommendation is 1 l/min. Allow the measurement to stabilize for three minutes before
starting the calibration.
• You can fill the entire incubator with the calibration gas. You can use calibration gas a
reference by putting the probe in a suitable chamber (for example, an incubator) and
filling that chamber with the calibration gas.
To perform a two-point adjustment, you need two calibration gases: one gas that is below
1000 ppmCO2 (low-end reference) and one that is above 2000 ppmCO2 (high-end
reference).
When supplying the gas from a gas bottle, make sure the gas bottle has stabilized to room
temperature before starting.
7.3.2. Effect of Environmental Compensations
The probe has various environmental compensations that improve its CO2 measurement
accuracy (see 2.4. Environmental Compensation (page 12)). As the calibration and
adjustment environment may differ from the actual measurement environment, you must
make sure that the compensation settings are properly set. Here are some key points to
remember:
• Pressure and temperature compensations have a significant effect on accuracy. If you
are using setpoint values instead of the values from the builtin temperature sensor or
an integrated system, make sure to correct the setpoints so that they correspond to
your calibration situation. Consider switching temperature compensation to use the
internal sensor and/or integrated system when calibrating, and then switching back
when calibration and adjustment is done.
• The effect of background gas compensations for humidity and oxygen may be
significant when using calibration gases, since these gases are often dry and oxygenfree. For example, pure nitrogen gas is typically used as a convenient 0 ppm CO2
reference. As it does not contain any oxygen or humidity, the compensations for them
must be set to zero.
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• Remember to restore the normal compensation settings after completing calibration
and adjustment. If you are integrating the calibration functionality of the probe as part
of a control software, also implement proper handling of the environmental
compensations.
7.3.3. Limits of Adjustment
The probe limits the amount of adjustment that is allowed to the CO2 measurement. The
maximum correction that you can apply is 1000 ppm + 25 % of the probe’s uncorrected
reading. Previous user adjustments do not affect this limit (the correction is not cumulative).
This feature limits the possible error introduced by incorrect adjustment.
For example, if you are adjusting using a 5000 ppmCO2 calibration gas, the maximum
correction you can apply is approximately 2250 ppm. Attempting to apply a greater
adjustment will fail. Notification of failure from the probe depends on the interface you are
using for adjustment.
7.3.4. Adjustment Types
You can adjust the CO2 measurement of the probe in one or two points.
• One-point adjustment is recommended if you are interested in maintaining a fixed CO2
level. For best result, use a calibration gas with a CO2 concentration that is close to the
intended level.
• Two-point adjustment is recommended if you typically measure a variable CO2 level.
Available adjustment functions depend on the interface you use to operate the probe. If you
want to integrate the functionality into a control system, the Modbus interface and the
Vaisala industrial protocol are recommended. If you want to compare the reading of the
probe to a reference instrument and adjust it accordingly, use an MI70 hand-held indicator
and a reference probe.
Vaisala Industrial Protocol
Vaisala industrial protocol supports one and two-point adjustment with the cco2 command.
Configuration of the environmental compensation settings can be done using serial line
commands.
Modbus
The environmental compensation settings can be configured using Modbus registers.
MI70 Hand-Held Indicator
MI70 hand-held indicator supports one-point adjustment, either using a calibration gas or
using a reference instrument that is connected to the MI70.
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7.3.5. DRW244827SP Calibration Adapter
The optional calibration adapter accessory can be used to feed a reference gas to the probe
through a gas port when calibrating. Gas flow should be in the range 0.5 ... 1.1 l/min,
recommendation is 1 l/min. Allow the measurement to stabilize for three minutes before
starting the calibration.
1
3
2
Figure 14 DRW244827SP Calibration Adapter with Probe Inserted
1
2
3
O-ring inside the adapter
Gas outlet on each side of the adapter
Gas port (port outer diameter 4.6 mm, port hole inner diameter 2 mm, suitable for
tubing with 4 mm inner diameter)
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Chapter 8 – Troubleshooting
8. Troubleshooting
8.1. Problem Situations
Problem
Possible Cause
Remedy
Analog output reading is
unchanging and appears
incorrect.
Analog output is in error state.
Remove the cause of the error
state and the analog output will
recover its normal function.
Probe outputs stars "****" on
serial line instead of measurement
data.
Incorrect supply voltage.
Check the power supply.
Check the active errors using the
ERRS command on the serial line.
Unsuitable operating
environment.
Verify that the operating
environment is within specified
operating limits.
Incorrect wiring.
Check that the RS-485 connection
is wired correctly.
Probe in POLL mode with
unknown address.
Power cycle or reset the probe
and try again.
Condensation on the sensor.
Remove the filter and check if
condensation has formed on the
sensor. If yes, dry out the
condensation with instrument air
and insert a new dry filter. Keep
the probe powered and operating
to prevent re-occurrence.
Unable to access probe on the
RS-485 line.
CO2 measurement not working.
More Information
‣ Wiring (page 20)
‣ Analog Output Error State (page 77)
8.2. Error Messages
The error messages are categorized according to the severity of the status:
• Critical errors are fatal to the operation of the unit. It may not be able to respond to
communication at all, and will not measure correctly.
• Errors prevent CO2 measurement and cause the analog outputs to be set to the error
state. Depending on the problem, errors may resolve themselves. For example, sensor
heating will eventually dry out condensation on the optical surfaces.
• Warnings do not prevent normal operation but may indicate possible problems.
• Status indicates a known state of the unit.
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Error Message
M211897EN-A
Description
Recommended Action
Program memory crc critical error
Program memory is corrupted.
Fatal error, contact Vaisala.
Parameter memory crc critical
error
Parameter memory is corrupted.
Fatal error, contact Vaisala.
Critical errors
Errors
Low supply voltage error
Check supply voltage.
Internal 30 V error
Low internal 30 V voltage.
Low RX signal error
Low input signal. Can be caused
by dirt or condensation on the
optical surfaces.
Internal 8 V error
Low internal 8 V voltage.
RX signal cut error
Signal distortion (EMC
interference)
Out of measurement range error
CO2 concentration is too high to
measure.
Sensor heater error
Sensor heater resistance is out of
range.
IR temperature error
IR source temperature error.
FPI slope error
Signal receiver error.
Internal 2.5 V error
Internal 2.5 V voltage out of
range.
Internal 1.7 V error
Internal 1.7 V voltage out of range.
Low IR current error
IR source failure.
Contact Vaisala.
Signal too low warning
Low input signal. Can be caused
by dirt or condensation on the
optical surfaces.
Continue normally.
Cut warning
EMC interference error limit
approaching.
Check for EMC interference
sources.
Unexpected restart detected
Transmitter is reset by watchdog
process.
Continue normally.
Wait to see if condensation is
removed by heat.
Wait for CO2 concentration to fall
into the measurable range.
Contact Vaisala.
Warnings
Status messages
CO2 adjustment mode active
76
Complete the CO2 adjustment.
Chapter 8 – Troubleshooting
8.3. Analog Output Error State
The probe sets the analog output channel into a defined error level instead of the measured
result in two situations:
• Probe detects a measurement malfunction. This means an actual measurement
problem, such as sensor damage or unsuitable environmental conditions.
• Measured value(s) are significantly outside the scaled output range.
The default error level depends on the output type:
Output
Default Error Level
0 ... 20 mA
23 mA
4 ... 20 mA
2 mA
0 ... 5 V
0V
0 ... 10 V
0V
The probe resumes normal operation of the analog output when the cause of the error state
is removed.
More Information
‣ Analog Output Overrange Behavior (page 14)
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Chapter 9 – Technical Data
9. Technical Data
9.1. GMP252 Specifications
Table 46 Performance
Property
Specification
Measurement range
0 ... 10 000 ppmCO2
(up to 30 000 ppmCO2 with reduced accuracy)
Accuracy at 25 °C and 1013 hPa (incl. repeatability and nonlinearity)
0 ... 3000 ppmCO2
±40 ppmCO2
3000 ... 10 000 ppmCO2
±2% of reading
Up to 30 000 ppmCO2
±3.5% of reading
Calibration uncertainty
at 2000 ppmCO2
±18 ppmCO2
at 10 000 ppmCO2
±66 ppmCO2
Long-term stability
0 ... 3000 ppmCO2
±60 ppmCO2/year
3000 ... 6000 ppmCO2
±150 ppmCO2/year
6000 ... 10 000 ppmCO2
±300 ppmCO2/year
Temperature dependence 0...10 000 ppmCO2
with compensation, -10 ... +50 °C
±0.05% of reading/°C
with compensation, -40 ... +60 °C
<±0.1% of reading/°C
without temperature compensation at
2000 ppmCO2 (typical)
-0.5% of reading/°C
Pressure dependence
with compensation at
0 ... 10 000 ppmCO2, 500...1100 hPa
±0.015% of reading/hPa
without compensation (typical)
+0.15% of reading/hPa
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Property
M211897EN-A
Specification
Humidity dependence
with compensation,
0 ... 10 000 ppmCO2, 0 ... 100 %RH
±0.7% of reading (at 25 °C)
without compensation (typical)
+0.05 % of reading/%RH
O2 dependence
with compensation, 0 ... 10 000 ppm%CO2, 0 ...
90 %O2
±0.6 % of reading (at 25 °C)
without compensation (typical)
-0.08 % of reading/%O2
Start-up, warm-up and response time
Start-up time at 25 °C
< 12 s
Warm-up time for full spec.
< 2 min
Response time (T90) with standard filter
< 1 min
Table 47 Operating Environment
Property
Specification
Operating temperature of CO2 measurement
-40 ... +60 °C
Storage temperature
-40 ... +70 °C
Humidity
0...100 %RH, non-condensing
Condensation prevention
Sensor head heating when power on
Electromagnetic compatibility
EN61326-1, Generic Environment
Chemical tolerance (temporary exposure during
cleaning)
• H2O2 (2000 ppm, non-condensing)
• Alcohol-based cleaning agents (for example
ethanol and IPA)
• Acetone
• Acetic acid
Pressure
Compensated
500 ... 1100 hPa
Operating
< 1.5 bar
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Chapter 9 – Technical Data
Table 48 Inputs and Outputs
Property
Specification
Digital output
Over RS-485:
• Modbus
• Vaisala Industrial Protocol
Analog outputs
• 0 ... 5/10 V (scalable), min load 10 kΩ
• 0/4 ... 20 mA (scalable), max load 500 Ω
Operating voltage
With digital output in use
12 ... 30 VDC
With voltage output in use
12 ... 30 VDC
With current output in use
20 ... 30 VDC
Power consumption
Typical (continuous operation)
0.4 W
Maximum
0.5 W
Table 49 Mechanics
Property
Specification
Weight, probe
58 g
Connector type
M12 5-pin male
Housing classification, probe body
IP65
Materials
Probe housing material
PBT plastic
Filter
PTFE
Connector
Nickel plated brass
Dimensions
Probe diameter
25 mm
Probe length
130 mm
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9.2. Spare Parts and Accessories
Information on spare parts, accessories, and calibration products is available online at
www.vaisala.com and store.vaisala.com.
Name
Order Code
Porous sintered PTFE filter for GMP252
DRW244221SP
Probe cable with open wires (1.5 m)
223263SP
Probe cable with open wires and 90° plug (0.6 m)
244669SP
Probe cable with open wires (10 m)
216546SP
USB cable for PC connection
242659
MI70 connection cable for probe
CBL210472
MI70 flat cable for GMP250 probes, M12 5 pin
CBL210493SP
Probe mounting clips (2 pcs)
243257SP
Probe mounting flange
243261SP
Calibration adapter
DRW244827SP
9.3. GMP252 Probe Dimensions
The dimensions are given in millimeters (mm).
130 mm, Ø 25 mm
12 mm
Figure 15 GMP252 Dimensions
82
76 mm
42 mm
Chapter 9 – Technical Data
9.4. 243261SP Mounting Flange
Dimensions
50
Ø 4.2
35.4
Figure 16 243261SP Mounting Flange Dimensions
Ø 60
5
5
17
Ø 36
Ø 25.6
Ø 28.5
Ø 42
Figure 17 243261SP Mounting Flange Dimensions, Cross Section
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GMP252 User Guide
9.5. 243261SP Calibration Adapter
Dimensions
Figure 18 243261SP Calibration Adapter Dimensions
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Appendix A – Modbus Reference
Appendix A. Modbus
Reference
A.1. Function Codes
Table 50 Supported Function Codes
Function Code (Decimal)
Function Code (Hexadecimal)
Name
03
03
Read Holding Registers
16
10
Write Multiple Registers
43 14
2B 0E
Read Device Identification
A.2. Modbus Registers
CAUTION! The decimal numbering of register addresses used in this manual is 1-based
(the register addresses start from 1). Note that the register addresses in actual Modbus
messages (Modbus Protocol Data Unit (PDU)) start from zero. Subtract 1 from the
decimal addresses presented in this manual to get the address used in the Modbus
message (for example, the decimal register address 1 (Measured CO2 value) becomes
register address 0 in the actual Modbus message).
Accessing unavailable (temporarily missing) measurement data does not generate an
exception. “Unavailable” value (a quiet NaN for floating point data or 0x0000 for integer
data) is returned instead. An exception is generated only for any access outside the
applicable register ranges.
A.2.1. Measurement Data
Table 51 Modbus Measurement Data Registers (Read-Only)
Address
(Decimal)
Address
(Hexadecimal)
Register Description
Data Format
Unit
1
00 00
Measured CO2 value
32-bit float
ppm
3
00 02
Compensation T
32-bit float
°C
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Address
(Decimal)
Address
(Hexadecimal)
Register Description
Data Format
Unit
5
00 04
Measured T
32-bit float
°C
257
01 00
Measured CO2 value
16-bit signed
integer
ppm (up to 32 000
ppm)
258
01 01
Measured CO2 value
16-bit signed
integer
ppm1) (scaled, up
to approx. 320 000
ppm)
1) The ppm output of the second Measured CO2 value register (address 258) is scaled and must be multiplied by 10.
A.2.2. Configuration Registers
CAUTION! Default power-up values (registers 513-519) are written into non-volatile
EEPROM memory. The EEPROM memory implementation has a limit of 30000 writes,
and is intended to be used only when saving long-term or permanent configurations.
Use the volatile memory (registers 521-527, values cleared on power-up) for nonpermanent configurations (for example, if the probe is used in a system that regularly
updates the compensation values).
Table 52 Modbus Configuration Data Registers (Writable)
Address
(Decimal)
Address
(Hexadecimal)
Register Description
Data
Format
Unit / Valid Range
513
02 00
Power-up value for
pressure
compensation
32-bit float
hPa
700 ... 1500 hPa
Operating <1.5 bar
(Init/default: 1013.25)
515
02 02
Power-up value for
temperature
compensation
32-bit float
°C
-40 ... +80
(Init/default: 25)
517
02 04
Power-up value for
humidity
compensation
32-bit float
%RH
0 ... 100 %
(Init/default: 0)
519
02 06
Power-up value for
oxygen compensation
32-bit float
%O2
0 ... 100 %
(Init/default: 0)
521
02 08
Volatile (value cleared
at probe reset)
pressure
compensation
32-bit float
Range 700...1500 hPa
(Init copied from power-up
value)
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Appendix A – Modbus Reference
Address
(Decimal)
Address
(Hexadecimal)
Register Description
Data
Format
Unit / Valid Range
523
02 0A
Volatile (value cleared
at probe reset)
temperature
compensation
32-bit float
Range -40...+80 °C
(Init copied from power-up
value)
525
02 0C
Volatile (value cleared
at probe reset)
humidity
compensation
32-bit float
Range 0...100 %RH
(Init copied from power-up
value)
527
02 0E
Volatile (value cleared
at probe reset)
oxygen compensation
32-bit float
Range 0...100 %O2
(Init copied from power-up
value)
769
03 00
Modbus address
16-bit
integer
Valid range 1...247 (default:
240)
770
03 01
Serial speed
enum
Valid range 4800...115200
0 = 4800
1 = 9600
2 = 19200
3 = 38400
4 = 57600
5 = 115200
(default: 2 (19200))
771
03 02
Serial parity
enum
0 = None
1 = Even
2 = Odd
(default: 0 (None))
772
03 03
Serial stop bits
16-bit
integer
Valid range 1...2
(default: 2)
773
03 04
Pressure
compensation mode
enum
0 = Off
1 = On
(default: 1 (On))
774
03 05
Temperature
compensation mode
enum
0 = Off
1 = Given
2 = Measured
(default: 2 (Measured))
775
03 06
Humidity
compensation mode
enum
0 = Off
1 = On
(default: 0 (Off))
776
03 07
Oxygen compensation
mode
enum
0 = Off
1 = On
(default: 0 (Off))
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Address
(Decimal)
Address
(Hexadecimal)
Register Description
Data
Format
Unit / Valid Range
777
03 08
CO2 filtering factor
16-bit
integer
Valid range 0 ... 100
(default: 100 (no filtering)).
For information on setting the
filtering factor, see A.4.
Filtering Factor (page 92).
To apply an accurate relative humidity compensation (775), you must also enable
temperature compensation (774) and pressure compensation (773).
A.2.3. Status Registers
Table 53 Modbus Status Registers (Read-Only)
Address
(Decimal)
Address
(Hexadecimal)
Register
Description
Data
Format
Notes
2049
08 00
Device status
16-bit
0 = Status OK.
1 = Critical error, maintenance needed.
2 = Error, device may recover
automatically.
3 = Warning.
2050
08 01
CO2 status
16-bit
0 = Status OK.
1 = CO2 reading not reliable. This
status also appears during transmitter
start-up.
A.2.4. Device Identification Objects
Table 54 Device Identification Objects
Object ID (Decimal)
Object ID
(Hexadecimal)
Object Name
Example Contents
0
00
VendorName
"Vaisala"
1
01
ProductCode
"GMP25x Carbon
Dioxide Probe "
2
02
MajorMinorVersion
Software version (for
example "1.2.3")
3
03
VendorUrl
"http://
www.vaisala.com/"
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Appendix A – Modbus Reference
Object ID (Decimal)
Object ID
(Hexadecimal)
Object Name
Example Contents
4
04
ProductName
"GMP25X "
128
80
SerialNumber1)
Transmitter serial
number (for example,
"K0710040")
129
81
Calibration date1)
Date of the factory
calibration
130
82
Calibration text1)
Information text of the
factory calibration
1) Vaisala-specific device information object
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A.3. Modbus Communication Examples
Reading CO2 Value
Device address used in the following examples is 240 (F0h).
The values returned by the device differ depending on the ambient conditions and/or
device settings. Your device might not return exactly same values.
Request
Response
Bytes on the Line
(Hexadecimal)
Description
Bytes on the Line
(Hexadecimal)
Description
(silence for 3.5 bytes)
Start of Modbus RTU
frame
(silence for 3.5 bytes)
Start of Modbus RTU
frame
F0
GMP25x address
F0
GMP25x address
03
Function (Read Holding
Registers)
03
Function (Read Holding
Registers)
00
Register address
04
Number of data bytes
D4
Value of first register
(least significant word)
00
00
Number of 16-bit
registers to read (2)
02
D1
43
Modbus RTU checksum
2A
(silence for 3.5 bytes)
7A
E8
33
End of Modbus RTU
frame
Value of second register
(most significant word)
Modbus RTU checksum
AB
(silence for 3.5 bytes)
End of Modbus RTU
frame
Register address: 1 (1-based Modbus documentation format) = 0000h (0-based format used
on the actual communications).
Data format: two 16-bit Modbus registers interpreted as IEEE 754 binary32 floating point
value, least significant word first.
Returned value: 43E8D47Ah, which is binary32 representation of 465.65997 (ppm).
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Appendix A – Modbus Reference
Writing Volatile Compensation Pressure Value
Request
Response
Bytes on the Line
(Hexadecimal)
Description
Bytes on the Line
(Hexadecimal)
Description
(silence for 3.5 bytes)
Start of Modbus RTU
frame
(silence for 3.5 bytes)
Start of Modbus RTU
frame
F0
GMP25x address
F0
GMP25x address
10
Function (Write
Multiple Registers)
10
Function (Write
Multiple Registers)
02
Register address
02
Register address
08
00
08
Number of registers to
write (2)
02
00
02
04
Number of data bytes
D4
50
Value for the first
register (least
significant word)
93
00
44
7D
Value for the second
register (most
significant word)
0E
Modbus RTU checksum
B7
(silence for 3.5 bytes)
Number of 16-bit
registers written (2)
End of Modbus RTU
frame
Modbus RTU checksum
(silence for 3.5 bytes)
End of Modbus RTU
frame
The response to a write function
informs that the function was
correctly received by the device.
It does not guarantee that the
written value was accepted by
the device (for example, in case
out-of-range values).
To verify that the value was
really accepted by the device,
read the register value after
writing.
Register address: 521 (1-based Modbus documentation format) = 0208h (0-based format
used on the actual communications).
Data format: two 16-bit Modbus registers interpreted as IEEE 754 binary32 floating point
value, least significant word first.
Value to write: 1013.25 (hPa), in binary32 format 447D5000h.
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A.4. Filtering Factor
Modbus register 777 sets the CO2 filtering factor. The filtering factor affects the speed at
which the latest CO2 measurement is integrated into the output of the probe. A new
measurement is produced approximately every two seconds.
By default, the filtering factory is set to 1.0, which means the latest measurement is shown
directly in the output, without any filtering. If the measuring environment produces
occasional exceptionally high or low readings that need to be averaged out in the output,
filtering can be applied.
To apply filtering, you need to set a filtering factor that determines how much the previous
measurements affect the calculation of measurement output. For example, when using
filtering factor of 0.1, the new output is a combination of previous measurements (90%) and
the latest measurement (10%).
Examples of the effect of filtering on output:
• Filtering factor 1.0 = No filtering, the latest measurement is output directly without
integrating previous measurements.
• Filtering factor 0.5 = The reading output shows ~75% of the measurement change after
two two-second measurement cycles and ~93% after four cycles.
• Filtering factor 0.1 = The reading output shows ~90% of the measurement change after
22 measurement cycles.
The configuration range of the filtering factor is 0 ... 100 in the 16-bit register: for example, to
set the factor to 0.5, set the value of the register to 50.
The following formula is used when calculating the output:
�new = �old �new − �old × �
onew
oold
mnew
f
92
New output
Previous output
New measurement
Filtering factor
Technical Support
Contact Vaisala technical support at helpdesk@vaisala.com. Provide at least the following
supporting information:
• Product name, model, and serial number
• Name and location of the installation site
• Name and contact information of a technical person who can provide further
information on the problem
For Vaisala Service Center contact information, see www.vaisala.com/servicecenters.
Warranty
For standard warranty terms and conditions, see www.vaisala.com/warranty.
Please observe that any such warranty may not be valid in case of damage due to normal
wear and tear, exceptional operating conditions, negligent handling or installation, or
unauthorized modifications. Please see the applicable supply contract or Conditions of Sale
for details of the warranty for each product.
Recycling
Recycle all applicable material.
Follow the statutory regulations for disposing of the product and packaging.
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www.vaisala.com
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