Dear Experts,

I have a system of S7-412 5H redundant bundle with two IM153-2 HF remote stations for IO modules, an unmanaged switch and PAC4200 energy analyzers.

I need to establish a redundant MODBUS/TCP communication with the PAC 4200 via the integrated PN ports of the CPUs and read some values of analyzers as MODBUS client.

So far, I tried to use the function blocks and the OB’s of “SIMATIC_ModbusTCP_PN_CPU_Redundant_DEMO” project (6AV6676-6MB10-0AX0) in my station and parametrized the data blocks with the Modbus/TCP PN Red Wizard. 

The problem I encounter is that, connection is established but all of the busy, done and error indicators are false according to the variable table in the demo. Moreover, when i look at  DB915,  there is something wrong with the parameters of the internally called function TSEND and TRCV. The id’s are assigned as 0 and there is an id mismatch  for the connections (8086).

The datablocks and OB’s used in the project are given in the screenshots.

Can you give me any suggestions about this event?

Hi,

after you downloaded the blocks into your PLC, have you done a restart or an initialization of the blocks?

What happens if you try to send a request(set ENQ_ENR)? Do you get a different error from the block? You need to set data_type, adress and length before you can send a telegram. If you do not send a telegram, the done, error and busy outputs are 0.

Hi Gwawl,

I could solve the problem by manually setting the init bit of the modbus block.

Thank you for your help.