Hi everyone,

I am trying to establish appropriate data exchange between CPU 1215C DC/DC/DC and Huawei SmartLogger3000 by using Modbus TCP.

I haven't got any problem to send/receive messages between my PC (using Modbus Master Simulator/Modbus server simulator) and PLC (server/client) or PC and logger (server). The problem appears when I connect PLC to the logger and then I cannot see any data flowing (I get status 7002 all the time without any errors).

Port 502 in both devices are enabled, IP addresses are in the same range and both devices have the same ID. I tired to change also MB_Unit_ID from FF to 1, then I receive error 8382: 'Invalid length specification in received Modbus frame. Check the server side'. The issue is, that from server side everything seems be fine. Siemens support team suggested to come back to FF or 7F, but it still didn't solve a problem.

Does anybody before struggle with such a problem?

Regards,

Andrzej

Hi Andrew,

I'm confronted with the same issues.

Did you get it running? 

"both devices have the same ID."

A Modbus client/master never has an ID.  Only Modbus server/slaves have an ID number.   Two Modbus server/slaves cannot communicate with one another, by the definition of what Modbus is.

Dear,

could you manage? I am intrested due to similar set up/issue's

Thanks

Davy

Dear,

I try to communicate with the smartlogger by S7-1500 CPU.

Huawei logger: 10.0.1.53 with port 502 / settings 

Siemens CPU 10.0.1.40 with port 0 (but i tried already several port settings)

MB_Client settings: 

Modbusmode: 103 (Modbusfunction 3)

Modbusdataadress: 40000 Len: 10

Connection ID: 1 (if i change the connection ID, the status is going into ERROR, so i assume that this is correct)

Status after enable mb_client: 7004 (so i assume that both partners are connected/linked)

Status during request: 7006 (during request, i see that the error  status is going 7006 and really short 80C8 and back 7006. and with no ERROR and No DONE and no BUSY

no data is read out of the register

Hello everyone,I'm working on a project where an S7-1200 PLC reads data from two counters via Modbus RTU in master mode. The PLC then applies arithmetic functions and calculations to this data.

I now want to configure the S7-1200 as a Modbus RTU slave so that my Huawei SmartLogger can read these values via Holding Registers (4xxxx).

My main question:

-   Where can I find the Modbus addresses of the data I want to read from the PLC?Calculated values are stored in MW, MD or DB in the S7-1200.

-   How can I find out which Modbus addresses these data correspond to when the PLC is in slave mode?