Beckhoff Bus Terminal Ethernet TCP/IP - Bus Coupler BK9000
Problem Solution Overview
Verify Modbus TCP/IP communication between ProSoft MVI56-MNET and Beckhoff Ethernet TCP/IP Bus Coupler BK9000 for Beckhoff digital and analog I/O bus terminal block configuration on 10/100BASE-T network.
Solution Brief
Our testing generated the following results:
- We were able to successfully communicate over Modbus TCP/IP with the device. (See below for configuration parameters used during the testing)
- The product supported Modbus functions 2-6, 15-16 and 23. The device tested supported integer read and write commands.
- Procedure used the sample MVI56-MNET ladder logic using RSLogix 5000 Version 8.0. No changes to the sample ladder were made.
- The purpose of our testing is to assure a level of compatibility in the communications between the two products. Through this testing, we attempt to identify problem areas that may arise when implementing the interface in the field.
EQUIPMENT
ProSoft MVI56-MNET communication module
Beckhoff Ethernet TCP/IP Bus Coupler BK9000with Ethernet communication.
Configuration:
The product testing was performed with the following settings used for the MVI56-MNET and BK9000 device.
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Ethernet Configuration
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Beckhoff IP Address
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192.168.255.3
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MVI56-MNET
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192.168.255.4
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Test PC
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192.168.255.1
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1756-ENET
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192.168.255.5
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Subnet Mask
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255.255.255.0
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Modbus Node Configuration
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Slave Address
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1
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Port
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502
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The test procedure used the hub cabling directions found in Ethernet Bus Coupler BK9000 Technical documentation Version 1.1 figure above.
Once the Ethernet cable is connected the dip switches are set to configure an address of XXX.XXX.XXX.3, switches 1&2 ON. The dip switches are used to configure only the last octet of the IP address. Switch 9-10 are set to off.
We ensured all devices used the same IP class of addressing. The test procedure used a Class C Netid (192.168.255.XXX)
Switches 1-8 represent the binary value for the 4th byte of the IP address
Ensure TCP communications by examining the LED indicators on the front panel. The link LED and ACT LED will show activity when you have established a good connection.
Then perform a ping command in a DOS window.
Follow the procedures found in the Ethernet Bus Coupler BK9000 Technical documentation Version 1.1 for additional information regarding IP setup. The above figures are derived from the this guide.
The following command list shows commands which were used to test the communications:
MNET configuration file used the following Client 0 Commands for the above tests: (a copy of this configuration file can be obtained from reference section below).The test used all of the default settings found in the sample configuration file and ladder logic.
[MNet Client 0 Commands]
#
# The file contains examples for a Modbus TCP/IP control using MBAP (port 502)
# and MNET (port 2000) service ports.
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#
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1
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2
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3
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4
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5
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6
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7
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8
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9
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10
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#Enable
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DB Addr
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Poll Delay
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Reg Count
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Swap Code
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Node IP Address
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Server Port
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Slave Address
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Func Code
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Address In Dev
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START
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1
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200
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0
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1
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0
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192.168.255.3
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502
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1
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4
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8
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1
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0
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0
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2
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0
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192.168.255.3
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502
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1
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6
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2056
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1
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204
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0
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1
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0
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192.168.255.3
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502
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1
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4
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1
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1
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4
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0
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1
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0
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192.168.255.3
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502
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1
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6
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2053
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1
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208
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0
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1
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0
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192.168.255.3
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502
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1
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4
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3
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1
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8
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0
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4
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0
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192.168.255.3
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502
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1
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6
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2055
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END
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The Beckhoff terminals provided for testing and the Modbus address offsetting are configured as follows:
Note: Beckhoff requires zero-based addressing, so all address found in the commands above are offset by one address.
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KL1012 -2ch 24Vdc digital input module:
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Ch1 - can be read at input register offset 9 - bit 0
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Ch2 - can be read at input register offset 9 - bit 1
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KL2012 -2ch 24Vdc digital output module:
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Ch1 - can be written at output register offset 2057 - bit 0
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Ch2 - can be written at output register offset 2057 - bit 1
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KL3002 -2ch +/-10Vdc Analog input module:
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Ch1 - can be read at input register offset 2
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Ch2 - can be read at input register offset 4
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KL4002 -2ch 0-10Vdc Analog output module:
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Ch1 - can be written at output register offset 2054
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Ch2 - can be written at output register offset 2056
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Notes about the terminal block configuration for the testing procedure:
Digitals:
The output from ch1 of the KL2012 is connected to the input of ch1 on the KL1012. So if you write a '1' to output register 2057, you should see ch1 of both the KL1012 and the KL2012 turn on.
The output from ch2 of the KL2012 is connected to the input of ch2 on the KL1012. So if you write a '2' to output register 2057, you should see ch2 of both the KL1012 and the KL2012 turn on.
If you write a '3' to output register 2057, you should see ch1 & ch2 of both the KL1012 & the KL2012 turn on.
Analogs:
The output from ch1 of the KL4002 is connected to the input of ch1 on the KL3002. The output and input values for the KL4002 & KL3002 respectively are represented by a 16bit signed integer as shown in the chart below:
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Numerical
Value
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Equivalent
Voltage
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0
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ov
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16384
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+5v
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32767
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+10v
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And everything in between is linear.
So if you write a value of 32767 to output register 2054, you will see a voltage of +10Vdc at Ch1 of the KL4002.
If you read from input register 2 (ch1 of KL3002), you should see a number close to 32767.
This is the same for Ch2 of both analog modules.
Our test command list performs the following functions.
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1.
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Read KL1012 Ch1-2 process value (Function Code 4)
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Function code
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4
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Starting register address
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8 (decimal zero-based)
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Number of registers
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1
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Type
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Scaled
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Expected Observation
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read Ch1 bits 0-1 MVI database address
200 bits 0-1
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2.
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Write KL2012 Ch1-2 process value command (Function Code 6)
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Function code
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6
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Starting register address
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2056 (decimal)
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Number of registers
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1
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Type
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Scaled
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Expected observation
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write Ch1bits 0-1 from MVI database address 0 bits 0-1
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3.
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Read KL3002 Ch1 process value (Function Code 4)
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Function code
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4
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Starting register address
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1 (decimal zero-based)
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Number of registers
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1
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Type
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16 bit signed integer
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Expected observation
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read Ch1 MVI database address 204
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4.
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Read KL3002 Ch2 process value (Function Code 4)
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Function code
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4
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Starting register address
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3 (decimal zero-based)
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Number of registers
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1
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Type
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scaled
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Expected observation
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read Ch2 MVI database address 208
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5.
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Write KL4002 Ch1 process value command (Function Code 6)
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Function code
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6
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Starting register address
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2053 (decimal zero-based)
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Number of registers
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1
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Type
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scaled
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Expected observation
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write Ch1 from MVI database address 4
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6.
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Write KL4002 Ch2 process value command (Function Code 6)
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Function code
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6
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Starting register address
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2055 (decimal zero-based)
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Number of registers
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1
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Type
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scaled
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Expected observation
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write Ch2 from MVI database address 8
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Performing the above test 5-6 we simply changed the value in the data objects and was able to read the values from the input terminals wired to loop back the output values into the input terminals.
The above tests were achieved utilizing the debug port on the MVI56-MNET and COMMVIEW software data analyzer.
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