I need to connect an OPC Server to Modbus/RTU device via rs232. What serial cable will I need cross or pin to pin?

Thanks.

 

First you need to know whether the Mobus device is a DTE or a DCE device.

Use this online pinout database:

http://rj485.com/index.php?main_page=pinout_db

If your device is a DCE, then wire straight thru.

If your device is a DTE, then cross pins.

Good luck