Hi there guys, I have a problem with connecting S7-1200 with Wago DI 750-362. I got connection status 7004, but there is no  reaction on the coils in TIAPortal. Screenshots [attached], if anybody can help me and point what i did wrong, thanks in advantage.

Hi,

TIA help: Description of MB_CLIENT > Description of Parameter REQ

Modbus query to the Modbus TCP server

The REQ parameter is level-controlled. This means that as long as the input is set (REQ=true), the instruction sends communication requests.

• After the Modbus query has started, the instance DB is locked for other clients.

• Changes to the input parameters will not become effective until the server has responded or an error message has been output.

• If the parameter REQ is set again during an ongoing Modbus request, no additional transmission takes place afterwards.

So in my opinion, you should not use a clock on input REQ, but a signal that is switched to TRUE once and then remains TRUE. Maybe that already solves it.

Regards,

Frink