Digisoft V3.25

Digisoft V3.25
Digisoft V3.25
FOR DIGITAL MFC
User's Manual
QUALIFLOW S.A.
Le Millénaire
395, rue Louis Lépine – B.P. 7
34935 MONTPELLIER - CEDEX 9
France
Ph#: +33 (0)4 67 99 47 47
Fax#: +33 (0)4 67 99 47 48
QUALIFLOW Technology Center
44862 Osgood Road
CA-94539
Fremont
CALIFORNIA – USA
Ph#: +1 (510) 440 93 74
Fax#: +1 (510) 440 93 75
QUALIFLOW Japan
3F Hattori Bldg.
30 Yotsuya
4 – Chome Shijuku-ku
Tokyo 160-0004
Japan
Ph#: +81 (0)3 5368 1682
Fax#: +81 (0)3 5368 1683
Identification
Reference D10-092
Document name
File name
Revision
V03
Digisoft V3.25 - User's Manual
Digisoft_V3_25_UserManual.doc
Date
24 / 12 / 2003
Control
Author
Visa
Date
Gilles Sanchez Dec 24, 2003
Verified
Visa
Date
Albin Diranzo Dec 24, 2003
Approved
Visa
Date
Mathieu Bourgarit Dec 24, 2003
History
Author
Pierre Navratil
Olivier Léonel
Gilles Sanchez
Gilles Sanchez
Gilles Sanchez
D10-092 - V03
Date
Description
Revision
Status
Dec 2000
Initial version
V00
Complete
Sept 01, 2003
Dec 23, 2003
June, 2004
Update to Digisoft V3.23
Update to Digisoft V3.24
Update to Digisoft V3.25
V01
V02
V03
Complete
Complete
Draft
Digisoft V3.25 for Digital MFC
User's Manual
TABLE of CONTENTS
1.
DESCRIPTION ................................................................................................................................. 1
2.
REFERENCE DOCUMENTATION............................................................................................... 1
3.
SCOPE & COMPATIBILITY ......................................................................................................... 2
4. SOFTWARE INSTALLATION....................................................................................................... 2
4.1. INSTALLATION PROCEDURE ............................................................................................................ 2
4.2. RUNNING DIGISOFT V3.25 ............................................................................................................. 6
4.3. COMMAND LINE PARAMETERS ........................................................................................................ 6
5. HARDWARE CONNECTION ........................................................................................................ 7
5.1. CONNECTOR ................................................................................................................................... 7
5.2. RS232C INTERFACE ....................................................................................................................... 8
5.3. RS485 MODBUS INTERFACE ........................................................................................................ 9
6.
SOFTWARE STARTING .............................................................................................................. 10
7. WINDOW TABS ............................................................................................................................. 12
7.1. SERIAL TAB ................................................................................................................................ 12
7.2. INFORMATION TAB .................................................................................................................. 13
7.2.1. Overview.............................................................................................................................. 13
7.2.2. MFC address ....................................................................................................................... 14
7.2.3. Valve type ............................................................................................................................ 14
7.2.4. Access level.......................................................................................................................... 15
7.2.5. Tools .................................................................................................................................... 16
7.3. CALIBRATION SLOT TAB ........................................................................................................ 17
7.4. REGULATION TAB .................................................................................................................... 18
7.4.1. Overview.............................................................................................................................. 18
7.4.2. Actuator menu...................................................................................................................... 19
7.4.3. Digital mode ........................................................................................................................ 19
7.4.4. Auto zero.............................................................................................................................. 19
7.4.5. External sensor .................................................................................................................... 20
7.4.6. Flow unit.............................................................................................................................. 21
7.4.7. Graphic area features.......................................................................................................... 21
7.4.8. Sample rate .......................................................................................................................... 24
7.4.9. Dynamic adjustment ............................................................................................................ 24
7.4.9.1. Overview........................................................................................................................ 24
7.4.9.2. Internal sensor................................................................................................................ 25
7.4.9.3. External sensor............................................................................................................... 26
7.4.10. Specific error message: error 140 ..................................................................................... 27
7.5. ALARMS TAB ............................................................................................................................. 28
7.5.1. Overview.............................................................................................................................. 28
7.5.2. Regulation monitoring ......................................................................................................... 28
7.5.3. Error parameters................................................................................................................. 29
7.5.4. History recorder .................................................................................................................. 30
7.6. OTHERS TAB .............................................................................................................................. 31
7.6.1. Overview.............................................................................................................................. 31
7.6.2. Ramp rate ............................................................................................................................ 31
7.6.3. Analog readout (On/Off)...................................................................................................... 32
7.6.4. Automatic Auto-zero (On/Off) ............................................................................................. 32
7.6.5. Readout DAC Offset ............................................................................................................ 32
7.6.6. Soft start (On/Off)................................................................................................................ 33
7.6.7. Total accumulator................................................................................................................ 35
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1. Description
This manual is designed for users of Digisoft V3.25 software; QUALIFLOW' software for digital mass
flow controllers communication.
For further information, feel free to contact your QUALIFLOW' sales representative. A list of Qualiflow's
representatives is available on our web site at www.qualiflow.com.
2. Reference Documentation
The following documents represent also an interesting source of information and give further information
on the use of Digisoft tools and options:
• SEMI E52-1000 Practice for referencing gases used in digital mass flow controllers;
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• External readout application note:
External_readout_MFC_Applications.pdf;
• Multicalibration application note:
Multicalibration.pdf.
Digisoft V3.25 for Digital MFC
1
3. Scope & Compatibility
This manual applies to QUALIFLOW Digisoft software V3.25.
Version 3.25 is compatible with MFC Firmware 7.40 and higher. A backwards compatibility has been
kept although support for the version 6.81 might present some weakness. However it is recommended to
upgrade your firmware to the last in-board software rev 7.40 for best results.
WARNING
Firmware V7.40 is not compatible with versions of Digisoft older than V3.25. Feel free to contact
Qualiflow for more information.
Required configuration:
Any compatible PC with 486 or Pentium processor with CD-ROM, 640x480 minimum screen size and
Microsoft Windows 95, 98, 2000 or NT4.x. Windows 3.1 is not supported. 3 Mb Hard disk drive space
and 8 MB RAM space are enough to run Digisoft.
4. Software Installation
4.1. Installation procedure
Installation:
• Insert the Qualiflow Digisoft CD-ROM into your disk drive;
• Browse the disk from your Explorer;
• Start the program file "Setup.exe" from the Digisoft directory on the CD-ROM;
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• Follow instructions on your screen to install Digisoft V3.25;
• Enter your name and company name;
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• Choose your installation directory on your computer or keep the default path;
• You can specify the program folder in the Start menu;
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• Before finishing the installation, a quick sum up is given below. Check information
and click next to finish copying Digisoft program files;
• Once files are copied, the following dialog ends the installation wizard:
NOTICE
When the installation wizard is completed, you do not need to restart your computer.
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4.2. Running Digisoft V3.25
Before starting the program, we do recommend to :
• Read carefully the whole manual;
• Connect one MFC on one mass-flow serial port prior to run Digisoft.
To start the program, see section 6 for further information.
4.3. Command line parameters
Command line parameters can be used with the executable file running the software.
The syntax is as follows:
C:\[directory]\Digisoft.exe param1 param2
Parameters:
• demo:
Digisoft enters demo mode. MFC is not needed in this mode;
• nologo:
the welcome logo does not show up;
• comX:
access directly the com number X; default com1;
• addY:
access directly the MFC number Y ; default add1;
• bdrZ:
set baud rate. (example : BDR19200; default BDR2400);
• ms:
allow for multi session.
Notice:
• When using comX parameter, others com port will not be scanned.
• Note that add0 brings an input query dialog box.
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5. Hardware Connection
5.1. Connector
Here is an illustration of a mass flow top connector for pin-out configuration:
For further information on connecting precautions, refer to the appropriate mass flow controller user's
manual. A wrong pin-out configuration could lead to major damages on your mass flow controller.
Digisoft uses the following pins for communication with a mass flow controller:
• 4 = GND RS232C;
• 7 = RX RS232C;
• 11 = TX RS232C.
The other pins of the top connector are used exclusively by the electronic card of the mass flow
controller.
Note: The power supply: +15V / 0V / –15V must be connected to the connector. For 1 or 2 mass flow
controllers, Qualiflow recommends the following power supply 6730025Q-01.
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5.2. RS232C interface
RS232 CORD
Q2001733-11
POWER
SUPPLY
+5/+15/-15
VDC
100 - 240 VAC
47 – 63 Hz
6730025Q-01
In order to connect also a computer through a RS232C cable, QUALIFLOW recommends to use one of
the following connector:
• Serial Connector adaptor with same SUB- D 15 pin-out: Q2001733-6 (model 4).
D Sub 15 pin
Male
MODEL 4
RS232C
D Sub 9 pin
Female
D Sub 15 pin
Female
• Serial Connector adaptor standard MFC Card-Edge Connector: Q2001733-08
(model 2).
RS232C
D Sub 9 pin
Female
MODEL 2
D Sub 15 pin
Female
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Card-edge
20 pin
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RS232C & Power Supply kit for Qualiflow Digital MFC’s all series
When connecting individually a Digital MFC to a computer, use an interface kit: Q2001733-12.
It includes :
• serial connector adaptor, P/N Q2001733-06;
• power supply assy 120/230 VAC, +/-15VDC, P/N 6730025Q-01;
• power cord from power supply to MFC, length 1 meter, P/N 2990976Q;
• RS232C cord from MFC to computer, length 2 meters, P/N Q2001733-11 SP.
5.3. RS485 MODBUS interface
2m50
1m00
0m50
RJ11 CORD
2990955Q.**.01.2m50
2990955Q.**.01.1m00
2990955Q.**.01.0m50
RS232/RS485
adapter
6730024Q-01
RS485/MODBUS accessories
When connecting several Digital MFC to a computer :
• RS232/RS485 converter, PN 6730024Q-01;
• RJ11-RJ11 cable 2m50, PN 2990955Q.**.01.2m50;
• MFC Power supply for 4 MFCs (+/- 15V), PN 6730025Q-01.
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6. Software Starting
Before starting the program, we do recommend to:
• read carefully the whole manual;
• connect one MFC on one mass-flow serial port prior to run Digisoft.
Then click on the following icon from the program folder of the Start menu of Windows:
Digisoft.exe
The introduction frame appears on screen:
Then the main Digisoft windows appears.
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Digisoft 3.25 will automatically recognize the baud rate available: 2400, 9600, 19200, 38400 baud rates.
The following window may appear:
• If no mass-flow is connected or if there is a bad connection;
• If the Modbus device identifier address of the mass-flow is not set to 1.
In case no mass-flow is connected or if there is a bad connection, Digisoft will scan from address 0 to 255
without being able to find any MFC. In case the Modbus device address of the mass-flow is not set to 1,
Digisoft will scan from address 0 until the Modbus device identifier address of the mass flow is found and
then the main Digisoft window will appear.
If you click "Cancel", the following warning message appears:
But Digisoft will continue to run without any MFC connected, leading to hazardous software results. In
this case when the main Digisoft window appears, click on "EXIT" to quit Digisoft and recheck your
mass flow controller connection (see section 5 for hardware connection).
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7. Window Tabs
7.1. SERIAL tab
This page is the default opening page when the software is started.
The software automatically chooses the first serial port on which a QUALIFLOW digital MFC is found.
However if there are several mass-flows connected on several serial communication ports, the scroll
down list allows to choose the serial communication port number.
NOTICE
At the bottom of each page, the status line indicates:
1. The number of the chosen calibration (named ‘Gas Slot’), the corresponding full scale, the unit,
as well as the corresponding process gas.
2. A communication progress bar.
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7.2. INFORMATION tab
7.2.1.
Overview
The identification frame provides you with the main identification parameters of the connected MFC:
• Manufacturer identifier;
• Product identifier;
• Serial number of MFC;
• Serial number of the sensor;
• Number of the soft version of the micro-controller inside the mass-flow controller
(firmware version);
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7.2.2.
MFC address
The "MFC address" frame allows to change or search for the Modbus address of the mass-flow. The
Modbus address allows to give a different address to each mass-flow when several mass-flows are on the
same cable (RS485 cable). As Digisoft 3.25 program is designed to run with only one mass-flow per
connection, it is not recommended to change the Modbus address.
7.2.3.
Valve type
According to the mass flow controller configuration, the respective checkbox is selected by default when
Digisoft starts (NO normally open or NC normally closed).
The two functions are activated in CUSTOMER access level. See section 7.2.4 for further details on
access level.
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7.2.4.
Access level
The "Access level" button asks for a password for more advanced functions.
Two levels access are set in Digisoft: BASIC and CUSTOMER. By default, when Digisoft is started, the
BASIC level is on. Password for CUSTOMER level is provided to the user if trained on Digisoft by
Qualiflow's engineers.
BASIC level
BASIC level is run by default when Digisoft starts. If you want to change to CUSTOMER level, select
the INFORMATION tab and click on "Access Level".
CUSTOMER level
To access this level, enter the password in the "Access Level" dialog box.
Advanced options are activated in the different tabs of Digisoft:
• Valve type selection
see section 7.2.3;
• External sensor on / off
see section 7.4.5;
• Dynamic adjustment for external sensor
see section 7.4.9.3;
• Gas slot parameters edition
Advanced parameters for qualified users;
• Calibration tab
Advanced parameters for qualified users.
WARNING
If the CUSTOMER level is used without Qualiflow support engineers approval, product warranty
is void as the use and modification of advanced parameters is restricted to Qualiflow's engineer.
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7.2.5.
Tools
The "Print" button allows to print a sheet with the configuration and identification parameters of the
mass flow controller.
The "Read" command button allows reloading the identification parameters of the mass flow controller.
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7.3. CALIBRATION SLOT tab
In this Digisoft tab, all calibrations available in memory are described with full scale, unit, gas process
name, gas process symbol, gas process SEMI Code (Ref: SEMI E52-1000 Practice for referencing gases
used in digital mass flow controllers) and the gas used during calibration.
The calibration curve can be selected changing the calibration slot from the scroll down list in
“Calibration slot currently in use”.
Make a new Gas Slot Wizard
This button accesses a wizard allowing to add a new gas slot by giving the requested gas and full scale.
WARNING
This option must only be used by qualified users who have been trained by Qualiflow's engineers.
Refer to specific documentation for further details on the use of this Digisoft option. See section 2 for
documentation references.
Tool
The "Read" button reloads data from the mass flow controller to fill the calibration slot table.
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7.4. REGULATION tab
7.4.1.
Overview
This is the main tab of Digisoft as it gives all necessary tools for mass flow controller operation.
The regulation can be chosen either in digital mode or analog mode:
• Analog mode: the setpoint is the 0-5V voltage applied on pin 8 of the SUB D15
connector;
• Digital mode: the setpoint is a numerical value transmitted by the RS232 or the
RS485 connection.
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7.4.2.
Actuator menu
This frame sets the actuator mode according to your requirements:
The actuator selector allows:
• Fully open
open the valve;
• Closed
close the valve;
• Regulation
Standard regulation mode;
• Hold last value
Keep the valve voltage constant;
• Direct Control
The setpoint is directly converted in valve command;
• Safe state
Goes in the safe state defined in the Alarm Page;
• Safe value
Applies to the valve the safe value defined in the Alarm Page.
7.4.3.
Digital mode
According to the mass flow controller configuration, the mode is automatically set when Digisoft starts.
The mode can be set by the operator as it is available in BASIC access level. See section 7.2.4 for more
details about access level on Digisoft.
In digital setpoint mode, the digital setpoint can be modified to predefined values by several aligned
buttons. An additional button allows to choose a specific setpoint using the up and down arrows or the
numerical keyboard.
Those buttons disappear when the analog setpoint mode is requested.
7.4.4.
Auto zero
The check box is refreshed whenever the program enters the regulation page:
• When checked, it means that the readout is affected by an offset which cannot
exceed –1.5%FS and +1.5%FS.
• Unchecked means that no correction is applied to the readout.
When the command is checked, the MFC invokes (only once) the “Zero adjust” service. The current
readout is captured and stored in non volatile memory. The captured readout is adjusted so that it does not
exceed –1.5%FS or +1.5%FS.
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Consequent readout values are corrected in the following way:
Readout = Readout – CapturedReadout
When the command is unchecked, the captured readout is cleared and consequent readout values are no
longer affected.
WARNING
Since the check box is only refreshed once when the program enters the regulation page, this
information may conflict with “Automatic auto zero” on page “Others”.
7.4.5.
External sensor
The MFC's external sensor feature can be used in different applications, such as pressure control in
vacuum process chamber, pressure control for wafer's back side cooling, evaporation control in gas
bubbler and burner flame temperature control using gas.
This option is off by default when Digisoft starts, according to the mass flow controller configuration:
The flow measure of the MFC is not involved in the regulation, it is just an information which is given to
the user. The regulation adjusts the valve command so that :
external sensor (V) = setpoint (V)
To activate this option, you need to enter the CUSTOMER access level. See section 7.2.4 for further
details on access level. Once activated, the REGULATION tab receives new features.
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Input / output format
• Flow readout:
0V
flow = 0 (Digisoft display : 0V or 0 % Full Scale.);
flow = MFC Full Scale (Digisoft display : 5V or 100% Full Scale.);
5V
• Setpoint:
between 0 and 5V (Digisoft display : xV or x% FS with 5V
• External sensor :
7.4.6.
100% FS);
between 0 and 5V. (Digisoft display : yV or y% FS
with 5V 100% FS or 10V 100% FS).
Flow unit
The setpoint and readout values are expressed in the selected unit.
If the option "External sensor" is activated in the REGULATION tab, the flow unit group is as follows:
7.4.7.
Graphic area features
A contextual menu is available using the right mouse button when the cursor is anywhere on the graphic
area. Right click to display the following menu:
Legend
A legend gives information about the curves color code of the current setpoint and readout values. The
legend may be hidden by using the contextual menu.
If the option "External sensor" is activated in the REGULATION tab, the legend includes the external
sensor as follows:
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Magnify
Double clicking with the left mouse button anywhere inside the graphic area allows to magnify. A new
double click restores its initial size. This can also be performed by using the contextual menu.
Here is an illustration of the Magnify mode for graphic area:
Current values for setpoint and readout are also displayed. They are displayed differently depending on
the graphic area mode used, normal or extended:
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If the option "External sensor" is activated in the REGULATION tab, the readouts includes the external
sensor as follows:
Zoom
You can zoom in by dragging a rectangle with the mouse around the area of interest.
IMPORTANT NOTICE
The rectangle must be dragged from top-left to bottom-right corner.
Un-zoom is performed by dragging a rectangle from bottom-right to top-left corner. Un-zoom can
also be performed by using the contextual menu.
While in zoom state, curves do not scroll and will disappear as lifespan expires.
Print
The contextual menu allows printing the current graphic on the default printer. It is recommended to
magnify the drawing before printing.
Clear
This command erases the current curve of the graphic area.
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7.4.8.
Sample rate
Acquisition can be started or stopped using the button below. The acquisition speed is also adjustable by
the sample rate cursor.
7.4.9.
Dynamic adjustment
7.4.9.1.
Overview
The "Dynamic Adjustment" command button opens a window to tune the PID of the system for the use
of an internal or external sensor and the valve. You need CUSTOMER level access to modify those
parameters. In BASIC level, parameters are read-only.
NOTICE
The interface of this window depends of the firmware version. If version is 7.40, the following
window appears. If firmware is older than 7.40, the old interface will appear.
Modifying dynamic parameters is restricted to qualified users only as you can damage the mass
flow controller. Only Qualiflow's engineer can grant you access to these parameters.
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7.4.9.2.
Internal sensor
If the external sensor option from the Regulation tab is off, the window shows the parameters for the
internal sensor and the valve group.
Three parameters can be modified with CUSTOMER level:
• St
Desired settling time (second).
• Beta
Adjustment coefficient (no unit);
• User readout filter
Cutting frequency (Hertz).
The internal sensor group is divided into three parts.
Sensor conditioning parameters:
• Tau2
Second order time constant (no unit);
• Gamma
• Sensor filter
Weighting coefficient (no unit);
Cutting frequency for sensor signal (Hertz).
Regulation parameters:
• K
Static gain (no unit);
• Tau
MFC time constant (second);
• St
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Desired settling time (second).
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User readout parameters:
• Beta
Adjustment coefficient (no unit);
• User readout filter
7.4.9.3.
Cutting frequency (Hertz).
External sensor
To access the interface of the external sensor regulation control parameters, the external sensor option
from the Regulation tab must be ON. In order to do so, you need to run Digisoft with CUSTOMER level
ON. See section 7.2.4 for further details about level access in Digisoft.
When "ON" is ticked, the following window shows the parameters for the external sensor.
Five parameters can be modified with CUSTOMER level:
• Kp
Gain (no unit);
• Ti
Integration time (second);
• Td
Derivate time (second);
• Beta
Adjustment coefficient (no unit);
• User readout filter
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Cutting frequency (Hertz).
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The external sensor group is divided into three parts.
Sensor conditioning parameters:
• A
Gain (no unit);
• B
Offset (percent of external sensor full scale);
• Sensor filter
Cutting frequency for external sensor signal (Hertz).
Regulation parameters:
• Kp
Gain (no unit);
• Ti
Integration time (second);
• Td
Derivate time (second).
As an example of PID regulation calibration method, you can read the following procedure, based on
Ziegler-Nichols method. The closed loop method prescribes the following procedure:
• Step 1: Disable any D and I action of the controller (Ti=1000; Td=0). Like a pure Pcontroller;
• Step 2: Make a setpoint step test and observe the response;
• Step 3: Repeat the SP test with increased / decreased controller gain until a stable
oscillation is achieved. This gain is called the "ultimate gain" Ku;
• Step 4: Read the oscillation period Pu;
• Step 5: Calculate the parameters according to the following formulas:
PI: Proportional gain = 0.45 x Ku
PID: Proportional gain = 0.6 * Ku
integral time =Pu / 1.2
integral time =Pu / 2
derivative time = Tu / 8
User readout parameters:
• Tau
Process time constant (second);
• Beta
Adjustment coefficient (no unit);
• User readout filter
Cutting frequency (Hertz).
7.4.10. Specific error message: error 140
The point needs to be done on a specific error message:
"error 140 : sensor error".
In Fully Open regulation, this message can appear because the flow signal measured by the sensor is
higher than the allowed values for full scale. In this particular case, the message doesn't state an error but
a normal running situation.
However, this message can appear permanently in any other regulation modes as a result of a circuit
failure or open circuit from the sensor.
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7.5. ALARMS tab
7.5.1.
Overview
7.5.2.
Regulation monitoring
The regulation monitoring panel contains all data to parameter the regulation alarm:
After the alarm delay, there will be an alarm if the readout is not contained between the (Flow – Delta
min) and the (Flow + Delta max).
The alarm delay is in seconds and the max and min Delta are in per thousand of the full scale.
The user chooses three parameters, the Delta min, the Delta max and the Delay alarm, to adjust the
regulation alarm. Delta min and Delta max (in ‰ FS) are the maximum differences between the readout
and the setpoint to assure before the delay time. If the MFC does not correctly regulate, the alarm is on
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until the user inhibits it. For example, if the pressure is too low, the MFC could not regulate the flow (see
the figure below), therefore an alarm signal will be generated until acknowledgment.
The regulation alarm also drives the regulation LED :
• Readout and Set-point inside the +/- delta: Green regulation LED On:
• Readout and Set-point outside the +/- delta from less than delay (transient time):
green regulation LED is blinking:
• Readout and Set-point outside the +/- delta from more than delay (regulation error):
green regulation LED is OFF and Red Alarm LED is ON if Alarm Warning is ON.
One issue with the regulation monitoring is that it may generate an alarm when there is no gas at the inlet
of the mass-flow controller because when there is no gas if the requested setpoint is above 0% the readout
will never be equal to the setpoint.
The mass flow controller is "intelligent enough" to detect when the readout and the setpoint are not equal
because there is no gas. However it has been observed that when there is no gas sometimes the regulation
monitoring can generate an alarm when setpoint is above 0%, so it is possible to switch off the alarm
warning due to the regulation monitoring. Note that if a hardware alarm occurs, it will generate an alarm
even if alarm warning is off.
7.5.3.
Error parameters
Clicking on the "Read and Acquit" button of the error panel allows to list the mass-flow internal errors
with their number and explanation.
The "Clear window" button erases the list of errors.
The "Safe state valve" fields allow setting the state of the valve when an error occurs.
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7.5.4.
History recorder
When the history recorder is "ON", the valve voltage, setpoint, reading of the sensor, error status and
flow are stored each xx seconds, where xx is the value written in the sample rate dialog. The sample rate
can be changed and the total time of recording is automatically refreshed.
The "Hold On Zero" function allows to record data only when setpoint is above 2% in order to avoid to
record mass-flow activities when there is no processing. When "Hold On zero" is "OFF", data is
recorded even when setpoint is zero.
The "Read History Data" button allows to consult all data in memory. Data is available in TXT format
and can be imported in Microsoft Excel (data saved as a cvs file). Predictive maintenance can be done
with a minimum training on mass-flow controllers. Here is the MFC history window:
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7.6. OTHERS tab
7.6.1.
Overview
This panel contains useful functions for the maintenance and particular applications:
7.6.2.
Ramp rate
The ramping function increases linearly the setpoint to assure a progressive increasing of the flow.
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It is expressed in milliseconds. A value of 0 ms disables the ramping mode. The maximum ramping time
is 10 hours, that is 36000000 ms. When ramping is active, the MFC calculates periodically the actual
setpoint so that the target setpoint is reached when the ramping delay expires and making a linear ramp.
7.6.3.
Analog readout (On/Off)
These checkboxes allow to avoid negative readout on the analog readout pin of the Sub-D connectors
(particular applications for supervisors compatibility).
7.6.4.
Automatic Auto-zero (On/Off)
If ON, after the given time of flow below 1.5%, the mass-flow will automatically proceed to an auto zero
(see section 7.4 for further details).
7.6.5.
Readout DAC Offset
An offset can be added to the readout value with a range of ±1000 mV. The purpose of this offset value is
to read 0V when gas flow is nil.
Type the value of offset in the text field and press the "Write" button.
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7.6.6.
Soft start (On/Off)
The Soft Start function avoids big overshoots when starting opening the gas flow in the line. This
overshoot, which appears when you suddenly open the supply valve, is due to the pressure wave which
travels from the supply valve to the mass flow controller. This pressure wave creates a rapid flow change
that the controller's sensor reads.
The Soft Start function will not reduce the spike. It will just delay the opening of the mass flow
controller valve so that the regulation is not disturbed by the spike. Many "hardware" solutions can reduce
this spike without playing with the Soft Start function:
• Check that the pressure upstream from supply valve is not too high. The pressure
drop across the MFC should not exceed 2bar (30psi). You can try to reduce the
upstream pressure and see if it affects the amplitude of the spike;
• If it is not enough, the best solution consists in placing the pressure regulator
between the supply valve and the MFC. In such a case the pressure regulator will
absorb the pressure wave and the spike should be reduced;
• Contact Qualiflow support team for further information.
When Soft Start function is ON, two parameters can be tuned:
• The "delay" parameter is the time between the setpoint change and the regulation
really starts. Set it first to about 3 seconds. This means that the mass flow controller
will wait 3 seconds before regulating. It should be enough time for the "pressure
spike" to decay. If you don't have spike anymore, set it to 0.05 second, and the MFC
will start working just after the setpoint change.
• For fine adjustment, the CUSTOMER level must be entered in order to access the
"Init valve" parameter. The "Init Valve" is the initial valve voltage applied to the
valve when the setpoint changes from a close position to a non zero setpoint value.
The mass flow controller applies "Init Valve" value for "Delay" time whenever the
setpoint passes from <1.5% to any >1.5% of full scale. This is to make sure the
valve is under control in pneumatic critical situations (e.g.: shut-off valves opening).
Note:
• If your flow controller is Normally Closed, try to increase the Init Valve value until
you get a reasonable settling time.
• If your flow controller is Normally Open, try to decrease the Init Valve value until
you get a reasonable settling time.
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Soft Start function for a Normally Closed MFC
Flow
SetPoint
Flow
Readout
Valve
Voltage
time
Soft Start
Delay
Consequence of a too low "Init Valve"
Flow
SetPoint
Flow
Readout
Valve
Voltage
Ideal
Init Valve
Soft Start
Delay
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Consequence of a too high Init Valve
Flow
SetPoint
Flow
Readout
Valve
Voltage
Ideal
Init Valve
time
Soft Start
Delay
7.6.7.
Total accumulator
The total value indicates the cumulative flow in sccm since the last initialization. It is useful to have a
look on the gas consumption.
• Total is memorized in non volatile storage when historic function is ON and will not
be reset in case of power shut-down;
• Total 2 will be automatically reset in case of power shut-down;
• Hour states the number of working hours for the mass flow controller.
Note that both total values are reset to zero when there is a change of calibration slot.
Total can be typically used to monitor the total gas consumption. Total 2 can be used to monitor gas
consumption during a process batch.
oOo
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