hi AP-TECH,

Modbus RTU is a Protocoll designed for RS485. I don´t think that it works with converter like this.

there are special Modbus converter that converts between different Modbus protocolls.

S7-PLCs are able to communicate over Modbus TCP over the internal Ethernet interfaces. To make them communicating to Modbus RTU devices, you need a converter from Modbus TCP to Modbus RTU or a CP that provides a Modbus RTU interface, like CM1241:

How do you establish a MODBUS-RTU communication with STEP 7 (TIA Portal) for the SIMATIC S7-1200?

 I recommend you to use the HW from this FAQ.

hope this helps,

regards,

 Hello,

AP-TECH

Hello,

I have a communication problem. I have a Simatic s7-1200 cpu 1214c DC/DC/DC driver and I want to communicate with a Modbus RTU device. I do not have a communication module for Modbus RTU (CM1241 type). Is it possible to use a simple Ethernet-RS485 converter (for example Waveshare 16530) or because it is Profinet and not Ethernet, I must have a Profinet-RS-485 converter?

Best Regards

 I think it's possible with that Waveshare 16530 but only in case you prepare complete Modbus RTU protocol over TCP by yourself. I think in case you're not good in Modbus protocol and communications generally skilled, I recommed to you buy serial module than fight with my idea.