Hello. Chitokota and others.
I am working with a simmilar device from Carlo Gavazzi. The EM340 version of the energy meter.

The comunication principle is the same from what I saw from both manuals. I can't seem to get my head around the message frame that needs to be sent to the energy meter to get the result of the used power.

The manual states that the messaga frame should be like this:

Physical address: 1 byte - 1 to F7h (1 to 247)
Function code: 1 byte 04h
Starting address: 2 bytes 0000h to FFFFh Byte order: MSB, LSB
Quantity of registers (N word): 2 bytes 1 to 14h (1 to 20) Byte order: MSB, LSB
CRC 2 bytes

So I made a DB with an array of 8 bytes.

So if I would want to read the used power from the energy meter I guess I need to send this:

Physical address -- Funcion code -- Starting address --  Quantity of registers -- CRC

             1             --          03H       --             0034h     --                   2              --   ?

The link to the Modbus manual, too see what I mean:

https://gavazzi.se/app/uploads/2020/11/em330_em340_et330_et340_cp.pdf

Any info on this topic would be great. Thank you.

Cheers

Aleix

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Split from Communicating Siemens S71200 cpu1215c and CB 1241 Rs485 module to Carlo Gavazzi EM24 energy meter via profibus.

Ok, some confusion is setting in...

Should I just use te ModbusMaster block and define what address I want to read?

So in ModbusMaster block I define:

MB_Addr = 1 (address of the CM340
Mode = 0 (read holding register)
Data_Addr = 300053
Data_Len = 2
DataPTR = my defined datablock with an array of 10 words

Cheers.

So I started tinkering with the communication.

Found a few manuals and videos online and on youtube.

I configured the Modbus_Comm_Load block  and the Modbus_Master blocks (I've attached a picture of the configuration).

On the Modbus_Comm_Load block when I set the Req input to ''1'' the status Changes from #7000 #7002 and goes back to #7000 but I don't get a Done signal.

Nontheless I tried the Req input on the Modbus_Master block and then I get the following error in the diagnostic buffer of the PLC.

-

Temporary CPU error: Area length error in FB 641
affecting OB 1 execution
write access DB area
Incorrect address, operand ignored
Processing will continue (no OB processing)

PLC_1 / PLC_1


Internal address details: Caddr=16#00000CD0, area: DB area, addr: 0
-

And the Modbus Master block outputs the following error: #8281

This is from the help

16#8281

Negative acknowledgment when writing module

Check the input at the PORT parameter.

You can find more detailed information on error causes in the static parameters Send_P2P.WRREC.STATUS or Receive_P2P.WRREC.STATUS, and in the description of the SFB WRREC.

Any info what could be wrong? The Port number is correct, so I don't know what else to try...

Cheers

Aleix