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T7B
Installation Manual
MAEN095, 2012-04
English
Foreword
Installation manual for T7B
Foreword
All operator panels are developed to satisfy the demands of human-machine
communication. Built-in functions such as displaying and controlling text,
dynamic indication, time channels, alarm and recipe handling are included.
The operator panel works primarily in an object-oriented way, making it easy to
understand and use. Configuration is carried out on a PC using the iX Developer
configuration tool. The project can then be transferred and stored in the operator
panel itself.
Various types of automation equipment such PLCs, servos or drives can be
connected to the operator panels. In this manual, the term “the controller” refers
to the connected equipment.
This manual explains how to install the operator panel. Please refer to the iX
Developer reference manual for further information.
Order no: MAEN095
Copyright © 2012-04 Beijer Electronics AB. All rights reserved.
The information in this document is subject to change without notice and is provided as available at the
time of printing. Beijer Electronics AB, including all its group companies, reserves the right to change any
information without updating this publication. Beijer Electronics AB, including all its group companies,
assumes no responsibility for any errors that may appear in this document. Read the entire installation
manual prior to installing and using this equipment. Only qualified personnel may install, operate or repair
this equipment. Beijer Electronics AB, including all its group companies, are not responsible for modified,
altered or renovated equipment. Because the equipment has a wide range of applications, users must acquire
the appropriate knowledge to use the equipment properly in their specific applications. Persons responsible
for the application and the equipment must themselves ensure that each application is in compliance with
all relevant requirements, standards and legislation in respect to configuration and safety. Only parts and
accessories manufactured according to specifications set by Beijer Electronics AB, including all its group
companies, may be used.
BEIJER ELECTRONICS AB, INCLUDING ALL ITS GROUP
COMPANIES, SHALL NOT BE LIABLE TO ANYONE FOR ANY
DIRECT, INDIRECT, SPECIAL, INCIDENTAL OR CONSEQUENTIAL
DAMAGES RESULTING FROM THE INSTALLATION, USE OR
REPAIR OF THIS EQUIPMENT, WHETHER ARISING IN TORT,
CONTRACT, OR OTHERWISE. BUYER'S SOLE REMEDY SHALL
BE THE REPAIR, REPLACEMENT, OR REFUND OF PURCHASE
PRICE, AND THE CHOICE OF THE APPLICABLE REMEDY SHALL
BE AT THE SOLE DISCRETION OF BEIJER ELECTRONICS AB,
INCLUDING ALL ITS GROUP COMPANIES.
Beijer Electronics, MAEN095
Contents
Contents
1 Safety Precautions .......................................................
1.1
General ...........................................................
1.2
During Installation ..............................................
1.3
During Use .......................................................
1.4
Service and Maintenance ........................................
1.5
Dismantling and Scrapping .....................................
2 Installation ...............................................................
2.1
Space Requirements .............................................
2.2
Installation Process ..............................................
2.2.1
2.2.2
Connections to the Controller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Other Connections and Peripherals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
3 Technical Data ...........................................................
4 Chemical Resistance ....................................................
4.1
Metal Casing .....................................................
4.2
Touch Screen and Overlay .......................................
4.2.1
4.2.2
4.2.3
4
4
4
5
5
5
6
6
7
10
12
12
13
Autotex F157/207 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Touch Screen Surface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
Autoflex EB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
5 Operator Panel Drawings ..............................................
5.1
Connectors .......................................................
5.2
Communication Ports ...........................................
5.3
T7B Outline .....................................................
6 Additional Installation Tips ............................................
6.1
Grounding the Operator Panel .................................
6.2
Ethernet Connection in the Operator Panel ...................
6.3
To Achieve Better EMC Protection .............................
6.4
Ambient Temperature ...........................................
6.5
Safety .............................................................
6.6
Galvanic Isolation ................................................
6.7
Cable and Bus Termination RS485 .............................
Beijer Electronics, MAEN095
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15
15
16
17
17
18
19
20
21
22
23
Safety Precautions
1
Safety Precautions
Both the installer and the owner and/or operator of the operator panel must read
and understand this installation manual.
1.1
•
•
•
•
•
•
•
•
•
•
•
•
•
General
Read the safety precautions carefully.
Check the delivery for transportation damage. If damage is found, notify the
supplier as soon as possible.
Do not use the operator panel in an environment with high explosive hazards.
The supplier is not responsible for modified, altered or reconstructed
equipment.
Use only parts and accessories manufactured according to specifications of
the supplier.
Read the installation and operating instructions carefully before installing,
using or repairing the operator panel.
Never allow fluids, metal filings or wiring debris to enter any openings in the
operator panel. This may cause fire or electrical shock.
Only qualified personnel may operate the operator panel.
Storing the operator panel where the temperature is lower/higher than
recommended in this manual can cause the LCD display liquid to
congeal/become isotopic.
The LCD display liquid contains a powerful irritant. In case of skin contact,
wash immediately with plenty of water. In case of eye contact, hold the eye
open, flush with plenty of water and get medical attention.
The figures in this manual serves an illustrative purpose. Because of the many
variables associated with any particular installation, the supplier cannot
assume responsibility for actual use based on the figures.
The supplier neither guarantees that the operator panel is suitable for your
particular application, nor assumes responsibility for your product design,
installation or operation.
It is recommended to turn on and shut down the operator panel at least once
before installing any components/cards or before connecting the operator
panel to external devices, like for example serial devices.
1.2
During Installation
•
The operator panel is designed for stationary installation on a plane surface,
where the following conditions are fulfilled:
–
no high explosive risks
–
no strong magnetic fields
–
no direct sunlight
–
no large, sudden temperature changes
•
•
•
•
•
Install the product according to the accompanying installation instructions.
Ground the product according to the accompanying installation instructions.
Only qualified personnel may install the operator panel.
Separate the high voltage, signal and supply cables.
Make sure that the voltage and polarity of the power source is correct before
connecting the product to the power outlet.
Beijer Electronics, MAEN095
4
Safety Precautions
•
Peripheral equipment must be appropriate for the application and location.
1.3
•
•
•
Keep the operator panel clean.
Emergency stop and other safety functions may not be controlled from the
operator panel.
Do not use too much force or sharp objects when touching the keys, touch
screen etc.
1.4
•
•
•
•
•
•
Service and Maintenance
Only qualified personnel should carry out repairs.
The agreed warranty applies.
Before carrying out any cleaning or maintenance operations, disconnect the
equipment from the electrical supply.
Clean the display and surrounding front cover with a soft cloth and mild
detergent.
Replacing the battery incorrectly may result in explosion. Only use batteries
recommended by the supplier. During the warranty period, the battery needs
to be replaced by an authorized Beijer Electronics service center.
1.5
•
During Use
Dismantling and Scrapping
The operator panel or parts thereof shall be recycled according to local
regulations.
The following components contain substances that might be hazardous
to health and the environment: lithium battery, electrolytic capacitor and
display.
Beijer Electronics, MAEN095
5
Installation
2
Installation
2.1
Space Requirements
•
•
Maximum installation plate thickness: 11 mm
Space requirements when installing the operator panel:
143
100 mm
100 mm
50 mm
50 mm
100 mm
204
Note:
The dimensions on the drawing are not proportional.
Beijer Electronics, MAEN095
6
Installation
2.2
Installation Process
The following is needed:
•
A Phillips/slot screwdriver
1. Unpack and check the delivery. If damage is found, notify the supplier.
Note:
Place the operator panel on a stable surface during installation.
Dropping it or letting it fall may cause damage.
2. Use the cut out dimensions that are included on the outline drawing to cut
a correct opening in the cabinet. A separate cut out drawing is available for
download from the Beijer Electronics web site.
3. Secure the operator panel in position using all the fastening holes and the
provided brackets and screws:
x4
Beijer Electronics, MAEN095
0.5 - 1.0
Nm
7
Installation
4. Connect the cables in the specified order, according to the drawing and steps
below.
Caution:
•
Ensure that the operator panel and the controller system have the same electrical
grounding (reference voltage level), otherwise errors in communication may
occur.
•
The operator panel must be brought to ambient temperature before it is started
up. If condensation forms, ensure that the operator panel is dry before connecting
it to the power outlet.
•
Ensure that the voltage and polarity of the power source is correct.
•
Use only shielded communication cables.
•
Separate high voltage cables from signal and supply cables.
B
Power
Controller
RS232/
RS422/
RS485
24V DC
24V DC
C
D
A
Ethernet
Connect cable A.
Connect cable B, using an M5 screw and a grounding conductor (as short
as possible) with a cross-section of minimum 2.5 mm2.
–
Connect cable C.
–
Connect cable D. The recommended cross-section of the cable is 1.5
mm2.
5. Carefully remove the laminated film over the operator panel display, to avoid
static electricity that could damage the panel.
–
–
2.2.1
Connections to the Controller
For information about the cables to be used when connecting the operator panel to
the controller, please refer to the help file for the driver in question.
Beijer Electronics, MAEN095
8
Installation
2.2.2
Other Connections and Peripherals
Cables, peripheral equipment and accessories must be suitable for the application
and its environment. For further details or recommendations, please refer to the
supplier.
Beijer Electronics, MAEN095
9
Technical Data
3
Technical Data
Parameter
T7B
Front panel, W x H x D
204 x 143 x 7 mm
Mounting depth
43 mm (143 mm including clearance)
Standalone mounting
VESA 75x75
Note: Maximum screw length for VESA mounting is 4 mm.
Usage of longer screws may lead to damage.
Front panel seal
IP 65
Rear panel seal
IP 20
Touch screen
material
Polyester on glass, resistive.
Overlay: Autotex F157 or F207*.
Touch screen
operations
1 million finger touch operations
Reverse side
material
Powder-coated aluminum
Frame material
Powder-coated aluminum
Weight
1.010 kg
Serial port for COM1
RS232 and COM2
RS422/RS485
9-pin D-sub contact with RS232 RTS/CTS, chassis-mounted
female with standard locking screws 4-40 UNC
Serial port for COM3
RS232 and COM4
RS422/RS485
9-pin D-sub contact with RS422 RTS, chassis-mounted
female with standard locking screws 4-40 UNC
Ethernet
1 x 10/100/1000 Mbit/s and 1 x 10/100 Mbit/s. Shielded
RJ45.
USB
3 x USB Host 2.0, max output current 500 mA
Processor
Intel® Atom
External storage
media
1 x SD card (optional)
Memory RAM
1 GB
LED
1 x multi-color
Real time clock
Yes (on chip)
Power consumption
at rated voltage
14 W
Fuse
3.15A Slow
Power supply
+24 V DC (18-32 V DC)
CE: The power supply must conform with the requirements
according to IEC 60950 and IEC 61558-2-4.
UL and cUL: The power supply must conform with the
requirements for class II power supplies.
Display
TFT-LCD. 800 x 480 pixels, 262 K colors
LED backlight
Active area of
display, W x H
152.4 x 91.4 mm
Operating
temperature
-10 ° to +50 ° C
Beijer Electronics, MAEN095
10
Technical Data
Parameter
T7B
Storage temperature
-20 ° to +70 °C
Relative humidity
5% - 85% non-condensed
Approvals and
certifications
Information is available on the web site
www.beijerelectronics.com
* See section Chemical Resistance for more information.
Beijer Electronics, MAEN095
11
Chemical Resistance
4
Chemical Resistance
4.1
Metal Casing
The frame and casing material is powder-coated aluminum. This powder paint
withstands exposure to the following chemicals without visible change:
Acetic acid 10%
Phosphoric acid 4%
Citric acid 10%
Phosphoric acid 10%
Diesel
Sea water
Distilled water
Sodium chloride 2%
Edible oil
Sodium chloride 20%
Fuel oil
Sulphuric acid 20%
Hydrogen peroxide 3%
Tap water
The powder paint shows limited resistance to the following chemicals at room
temperature:
Butanol
Nitric acid 3%
Hydrochloric acid 5%
Nitric acid 10%
Isopropyl alcohol
Phosphoric acid 43%
Na-hypochlorite 10%
Turpentine
Note:
If exposure to any of the above chemicals is demanded, it is recommended to first test
the chemical on an “invisible” spot of the metal casing.
The powder paint shows little or no resistance to the following chemicals at room
temperature:
Acetic acid, conc.
Methyl-ethyl ketone
Toluene
Acetone
Nitric acid 30%
Trichlorethylene
Ammonia 5%
Phenol
Xylene
Ammonia, conc.
Sodium hydroxide 5%
97 octan unleaded petrol
Ethyl acetate
Sodium hydroxide 30%
98 octan leaded petrol
Beijer Electronics, MAEN095
12
Chemical Resistance
4.2
Touch Screen and Overlay
4.2.1
Autotex F157/207
Autotex F157 or F207 covers the overlay surrounding the touch screen.
Solvent Resistance
Autotex F157/F207 withstands exposure of more than 24 hours duration under
DIN 42 115 Part 2 to the following chemicals without visible change:
Acetonitrile
Diesel Downey / Lenor1
Phosphoric acid (<30%)
Ajax / Vim in solution
Ethanol
Potassium ferricyanide
Alkalicarbonate solution1
Glycerine
Potassium hydroxide
(<30%)
Ammonia (<40%)1
Glycol
Pure Turpentine
Acetic acid (<50%)
Gumption1
SBP 60/951
Ariel powder in solution1
Hydrochloric acid (<36%)
Sulfuric acid (<10%)
Bleach1
Linseed oil
Tomato ketchup
Castor oil
Methanol
Trichloroacetic acid
(<50%)
Caustic soda (<40%)1
Nitric acid (<10%)
White Spirit
Cutting oil
Paraffin oil
Windex1
Cyclohexanol
Persil powder in solution1
Wisk
Diacetone alcohol
Petroleum spirit1
-
1 Extremely faint glossing of the texture was noted.
Autotex withstands DIN 42 115 Part 2 exposure of up to 1 hour duration to glacial
acetic acid without visible change.
Autotex is not resistant to high pressure steam at over 100 °C or the following
chemicals:
Concentrated mineral acids
Benzyl alcohol
Concentrated caustic solution
Methylene chloride
Beijer Electronics, MAEN095
13
Chemical Resistance
4.2.2
Touch Screen Surface
The touch screen surface on the operator panel withstands exposure to the
following solvents without visible change:
Solvents
Time
Acetone
10 minutes
Isopropanol
10 minutes
Toluene
5 hours
4.2.3
Autoflex EB
It is recommended to use the Autoflex EB touch display protection film, that can
be ordered from Beijer Electronics.
Solvent Resistance
Autoflex EB withstands exposure to the same chemicals as Autotex F157 or F207
according to section Autotex F157/207.
Outdoor Use
In common with all polyester based films Autotex EB is not suitable for use in
conditions of long term exposure to direct sunlight.
Beijer Electronics, MAEN095
14
Operator Panel Drawings
5
Operator Panel Drawings
5.1
Connectors
Pos.
Connector
Description
1
Power supply
+24 V DC (18-32 V DC)
2
COM 1/2
Communication Ports
3
LAN (Port 2)
1 x 10/100 Base-T (shielded RJ-45)
4
USB
2 x USB Host 2.0, max output current 500 mA
5
Headphone
Headphone Connector
6
LAN (Port 1)
1 x 10/100/1000 Base-T (shielded RJ-45)
7
COM 3/4
Communication Ports
5.2
Communication Ports
Pin
Serial port, 9-pin female
Serial port, 9-pin female
COM1
COM3
1
COM2
RS422 TX+ /
RS485 TX+/RX+
RS422 TX+ /
RS485 TX+/RX+
2
RS232 RX
RS232 RX
3
RS232 TX
RS232 TX
4
5
RS422 RX+
GND
6
GND
RS422 TX- /
RS485 TX-/RX-
COM4
RS422 RX+
GND
GND
RS422 TX- /
RS485 TX-/RX-
7
RS232 RTS
RS422 RTS+
8
RS232 CTS
RS422 RTS-
9
RS422 RX-
RS422 RX-
Note:
Drawing for external cable CAB109 (drawing # Z7100-029E) is available on the web site:
www.beijerelectronics.com
Beijer Electronics, MAEN095
15
Operator Panel Drawings
5.3
T7B Outline
143
Ethernet
COM3 RS232
COM4 RS422/RS485
24 V DC
COM1 RS232 /
COM2 RS422/RS485
204
7
max 11 mm
material thickness
SD memory
card slot
USB host
43
9
126
9
9
187
Expansion port
9
Note:
A Step CAD file is available on the web site www.beijerelectronics.com
Beijer Electronics, MAEN095
16
Additional Installation Tips
6
Additional Installation Tips
When experiencing communication problems in for example noisy environments
or when operating close to temperature limits, the following recommendations
are to be noticed.
6.1
Grounding the Operator Panel
Mounting plate in the cabinet
Door
Operator panel
3
2
Power supply
1
Ferrite core
24 V DC
5
6
4
5350
The operator panel’s mounting clamps do not provide a secure grounding
connection between the panel and the device cabinet, see 1 in drawing above.
1. Connect a 2.5 mm2 wire between the operator panel’s quick-connect plinth
and the panel’s chassis, see 2 in drawing above.
2. Connect a 6 or 4 mm2 wire or grounding braid between the operator panel’s
chassis and the closest grounding point on the door, see 3 in drawing above.
3. Connect a strong but short grounding braid between the door and the device
cabinet, see 4 in drawing above.
4. Twist the cables onto the 24 V DC feed, see 5 in drawing above. Minimum
cross-section of the cable is 2.5 mm2.
2 turns around the ferrite core provide 4 times the suppression of 1 turn.
3 turns around the ferrite core provide 9 times the suppression of 1 turn.
A ferrite core suppresses disturbances to the 24 V feed, see 6 in drawing above.
Note:
The grounding wires should be short and the conductor should have a large area.
A long, thin grounding wire has a very high impedance (resistance) at high frequencies
and will not guide disturbances to the ground.
Multi-wire conductors are better than single wire conductors with the same area.
A braided conductor wire with the same area is even better. The best is a short, thick
grounding braid.
Beijer Electronics, MAEN095
17
Additional Installation Tips
6.2
Ethernet Connection in the
Operator Panel
Industrial Ethernet
RJ45
RJ45
1
RJ45
RJ45
Operator panel
RJ45
3
2
Operator panel
RJ45
4
Shielded
1-1
2-2
3-3
Short and
unshielded
Operator panel
RJ45
8-8
5
Operator panel
RJ45
0.1 uF
250 V
5351
In some industrial units for Ethernet, the RJ45 contact’s shield is connected to the
chassis via a capacitor, see 1 in drawing above.
The operator panel’s Ethernet shield is directly connected to the chassis, see 2 in
drawing above.
1. Check whether the other Ethernet unit has its shield directly grounded or
grounded via a capacitor.
Note:
In many cases, connecting the shielded Ethernet cabling to the chassis at both ends is
inappropriate. Hum or grounding loops can occur. Unshielded cabling may even result
in fewer communication errors.
A good solution may be to use a shielded Ethernet cable, but to connect the shield
at one end only.
One option is to break the shield, see 3 in drawing above.
A more elegant method is to expand the shielded Ethernet cabling with a piece of
unshielded Ethernet cable, see 4 in drawing above.
You can ground the shield via an external 0.1 uF/250 V plastic capacitor, see 5 in
drawing above. This will connect the HF transients to the ground.
Beijer Electronics, MAEN095
18
Additional Installation Tips
6.3
•
•
•
•
•
•
•
•
To Achieve Better EMC Protection
Initially, use the original cabling from Beijer Electronics primarily.
Use shielded cables for RS232 communication.
Use twisted pair and shielded cabling for RS422 and RS485.
Use the cabling intended for the bus type; Ethernet, Profibus, CC-Link,
CAN, Device Net etc.
Install and connect according to applicable specifications for the relevant bus
standard.
Use shielded cabling for Ethernet, preferably with foil + braided shield.
D-sub covers should be shielded, and the shield should be connected to the
cover 360 ° where the cable comes in.
Connect the shield at both ends.
Shielded cable
0.1 uF/250 V
Ground plane 1
Ground plane 2
Not same potential
5352
Ground plate
Ground plate
in another building
With longer distances, there is a risk that the ground potential may be different.
In that case, the shield should only be connected at one end. A good alternative
is to connect the other end of the shield to the ground via a 0.1 uF/250 V plastic
capacitor. Both ends are then connected to the ground in terms of HF, but only
connected to the ground at one end in terms of LF, thus avoiding the 50 Hz
grounding loops.
Metal cabinet
Metal cabinet
Terminal or connector
Short distance
Terminal or connector
EMC cable gland
Shielded cable
Cable clamp
in steel
Plastic cable gland
Shielded cable
5353
1. Use an EMC cable gland or regular plastic cable gland, remove the outer jacket
and connect the shield to the installation plate with a 360 ° metal cable clamp.
2. Place the 24 V DC and communications cabling in one cable trunk/cable duct
and 230/380 V AC in another. If the cables need to be crossed, cross them at
90 ° only. Avoid combining the cabling for stronger 24 V DC outputs with
the communication cabling.
Ferrite cores that are snapped onto the shielded cabling may remove minor
disturbances. Large ferrite pieces that are snapped onto unshielded cabling and
where the wires go 2-4 times around the cores are approximately 5-25 times more
efficient.
Beijer Electronics, MAEN095
19
Additional Installation Tips
6.4
Ambient Temperature
The maximum ambient temperature for the operator panel is provided in the
specifications. The ambient temperature refers to the temperature in the device
cabinet which cools the operator panel’s electronics.
Top
50 °C inside
Operator
panel
Power
Power
30 °C outside
Axial fan
120 x 120 mm
Middle
45 °C inside
Airflow
Power
Bottom
40 °C inside
5354
In most cases, the ambient temperature for the operator panel is significantly
higher than the device cabinet’s ambient temperature.
If the cabinet is tall and there are a number of heat-generating devices, the
temperature at the top of the cabinet will be considerably higher than the
theoretical temperature increase that would be expected. All electronics are
sensitive to heat. The lifespan of an electrolytic capacitor is cut in half with an
8-10 °C increase in temperature. A 15-20 °C temperature increase results in a
quarter of the lifespan etc.
Rittal has a good program for estimating the anticipated average temperature in
the cabinet as well as a large program for controlling the temperature in the device
cabinet.
An enamel-coated steel cabinet has a radiant heat value of 5.5 W/m2 and degrees
C.
Installing a fan inside the cabinet will even out the temperature, while moving air
provides considerably better cooling than still air.
Install the fan so that it sits in the cooler area and will blow cold air against the
operator panel. If the fan is mounted at the top and sucks air upwards, the fan’s
ambient temperature will be higher = shorter lifespan.
The operator panel’s loss effect = supply voltage x current. Virtually no power goes
to external users and no loss effects due to inputs.
Beijer Electronics, MAEN095
20
Additional Installation Tips
6.5
Safety
Most of the operator panels are fed with 24 V DC.
Power supply
230 V AC to 24 V DC
Operator panel
+24 V
1
0V
4
Power supply
230 V AC to 24 V DC
Operator panel
+24 V
2
0V
4
Distance?
Power supply
230 V AC to 24 V DC
Operator panel
+24 V
3
0V
4
COM1
Small controller with expansion unit
Ch0
Ch1
230 V AC
COM100
Ch100
Ch101
5355
If you use a power supply that meets safety standards and only feeds the operator
panel, there is no problem. See 1 in drawing above.
However, if you have a 24 V unit that also feeds other units, there is reason to be
cautious, see 2 in drawing above. The operator panel does not have insulation that
meets safety requirements in the event of a potential short circuit between 230 V
AC and 24 V DC. It is assumed that the 24 V feed is secure, for example, SELV
according to EN 60950 (protection against electric shock) and UL 950.
Example:
Here is an example that explains why a secure 24 V DC feed can be ruined by mixing 24
V relay contacts with 230 V AC relay contacts in a smaller controller. Check that the
“clearances and creepage distances between 24 V DC and 230 V AC fulfill EN 60950 or UL
950”. If not, input a separate 24 V unit into the operator panel.
If there is a substantial distance between the relay contacts for 24 V DC and 230 V
AC, it is OK to use the same 24 V devices for all feeds. See 3 in drawing above.
Connect 0 V on the 24 V feed to the ground, see 4 in drawing above. This offers
three advantages:
•
Safety is increased. The 24 V feed will not be live in the event of a faulty
connection or short circuit between 0 V (24 V) and 230 V phase.
•
Transients on the 24 V feed are connected to the ground.
•
No risk that the 24 V feed is at a high level in relationship to the ground. This
is not unusual since there is high static electricity.
Beijer Electronics, MAEN095
21
Additional Installation Tips
6.6
Galvanic Isolation
Internal electronic
Filter
Ethernet
DC/DC
galvanic isolation
DC/AC
VCC
+24 V DC
CFL
0 V (GND)
0V
1.5 m
RS422/485
RS232
USB
5356
USB
The operator panel has galvanic isolation against the 24 V DC feed but no galvanic
isolation between the communication ports for RS232, RS422/485 and USB.
Only the Ethernet connection has galvanic isolation.
Operator panel
Modular controller
Power CPU
RS422
*
RS232
*
* * *
USB
*
PC
*
Not same ground potential
* = Internal 0 V (GND) connection
Printer
COM COM2
*
PC
*
5357
When a PC is connected to the operator panel, the panel’s internal 0 V (GND) will
be connected to the protective ground via the PC.
A number of USB devices can have the shield connected together with the
protective ground. Here, the operator panel’s 0 V (GND) is connected to the
protective ground when, for example, a USB memory stick, keyboard or similar
device is plugged in.
If a number of units are connected that have a 0 V and a ground connection, and
these are connected to various grounding points, there is a substantial risk of
problems. Grounding currents go through communication cables, the rear plate
of the controller, and internally in the operator panel, and can cause errors.
Use external units to improve communication and achieve galvanic isolation.
Westermo has good industry-standard insulators that are also insulated from the
24 V DC feed.
Note:
It is very important to make sure that the 24 V feed in the external insulation unit is not
connected to one of the communication outlets. If it does not have 100% insulation
against the 24 V feed, disturbances and grounding currents from the 0 V on the 24 V
side will disrupt communication.
Using this type of unit solves one problem but creates a larger problem! A substandard
installation may work now, but problems may arise when other devices are connected.
Beijer Electronics, MAEN095
22
Additional Installation Tips
6.7
•
•
•
Cable and Bus Termination RS485
Use shielded and twisted pair cable. The pair capacitance may not exceed 52.5
pF/m and area at least 0.25 mm2 (AWG 24), if you want to use the maximum
transfer distance and maximum transfer speed.
0 V, the reference voltage for communication should be included in
the cabling. With two-way communication use two pairs; one pair for
communication and one pair for 0 V.
The shield must be grounded at one end. The other end is usually grounded,
but with longer distances or when there is a difference in the ground potential,
the shield should be connected to the ground via 0.1 uF/250 V plastic
capacitor to prevent ground current in the braided shield. A number of
manufacturers recommend that the shield be grounded at each node. Various
manufacturers have different systems for bus termination.
Depending on the recipients’ design, the bus wires may be on the same level or
require pull-up or pull-down to ensure that no faulty signals are detected when the
bus is in resting mode (all transmitters are disconnected).
Beijer Electronics, MAEN095
23
Head office
Beijer Electronics AB
Box 426
201 24 Malmö, Sweden
www.beijerelectronics.com / +46 40 358600
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