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Setting up a Write_Var command to have a M340 PLC write data directly to a supported TCP/IP device.

Goals and Symptoms

M340 & Write_Var

Causes and Fixes

Open your Unity Project and create a new Ethernet Network


Configure the Ethernet network according to your application. Don't forget to Validate your changes.



Next Link the Network to the correct Ethernet port in the configuration



Next go to Tools and Project Settings



In the Project Settings that the last 3 items in the Data types field are checked off.
This will allow us to directly enter Arrays into our project rather than having to first declare them as variables.



Next add a ADDM block to your Unity program, link the OUT pin to the ADR pin of the Write_Var block, and enter the appropriate String (according to your Network configuration) to the IN pin
Note: The Syntax of the IN parameter of the ADDM block for Ethernet is explained in additional FAQs.

For this Example the Net Link id "Ethernet_1" and the IP address of the TCP/IP device is 192.168.40.11.
Remember that this input is a String so you need ' before and after the text.




Next configure the remaining parameters of the Write_Var block where:

OBJ = String declaring the type of object to Write (%MW or %M)
NUM = The starting register address in the Slave device to were the data will be sent
NB = The # of registers to write
GEST = Array of length 4 where the Management Exchange table for the Write_Var is located
EMIS = Array of length NB where the Write data is stored in the M340.
Note: The Array's are of type INT if declared as variables.




Finally build, download, and run the program

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