I am working on a project that involves connecting a Koyo D2-250 with a Ritron radio using modbus. Any suggestion on the pinout from the seven pin RS 485 to the RS232C?

 

RS-485 is a 2-wire differential hardware interface
which cannot be directly connected to an RS-232C
port. It is designed to be a half-duplex multi-drop protocol. You will need some sort of interface or converter. There are many models out
there. I have used B&B Electronics model 485019TB
on several occasions with good results. Info is
available on their website at www.bb-elec.com.
They have a down-loadable catalogs and data sheets in .pdf format. Good luck.

 

I recommend "Integrity Instruments" RS232 to RS485 converter. Under 60 dollars, it works excellent.