Modbus for S7 300

I going to using modbus for Communication with third party..
But I can't look for Modbus module at siemens sales catalog.

How should i do it?

look for the additional convertor? ( TCPIP to Modbus )??

Rgds

I'm not sure if this is what you're after

I'm using the 341-1CH01-OAEO serial communication module to communicate modbus RTU with some GE Multilin 369 units and some Yokagowa UT-550 controllers.

In addition to the module, you'll have to purchase the modbus driver.

Hello, teh;
When purchasing the Modbus driver for the CP340/CP341, make sure you know whether you will be Modbus master or slave; there are 2 different drivers in the Siemens catalog.
Once you have the driver installed, use the example project that comes in the documentation for the CP340/CP341 (you can download it from the Siemens webpage) to establish a basic communication link; then modify it to suit your needs. It is the easiest way to make sure all functionnalities are available to you.
Hope this helps,
Daniel Chartier