Modicon M340 Variable Addressing

northwest_trail · Dec 12, 2008

Hello,

Considering the M340 as a Modbus slave, and another device attempting to access internal memory of the M340 using the standard holding register format (4xxxx), is there a way to map the internal memory words (%MW) to the holding registers?

For example, if I want to provide %MW200 to the Modbus master when they reference address 40001, how do I do this?

Thanks in advance.

tragically1969 · Dec 14, 2008

northwest_trail said:
Hello,

Considering the M340 as a Modbus slave, and another device attempting to access internal memory of the M340 using the standard holding register format (4xxxx), is there a way to map the internal memory words (%MW) to the holding registers?

For example, if I want to provide %MW200 to the Modbus master when they reference address 40001, how do I do this?

Thanks in advance.

Assuming your master does not need an offset:

When looking at the PLC from a a master on Modbus register %MW200 would be Modbus address 40200 so 40001 is %MW1 so if you want %MW200 to be at 40001 you would need to use the MOV or other command to move the contents of %MW200 to %MW1

northwest_trail · Dec 14, 2008

Thanks for the help

Modicon M340 Variable Addressing

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tragically1969

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