Interfacing devices to PLC via RS232

[techie]

I was wondeeing if it is possible to hookup custom made devices like process displays or weigh scals to the serial port of PLCs. I am interested in interfacing to Siemens PLCs.

 

[Mr_Programmer]

This is possible, but the standard port of a Siemens PLC is not RS232. In google you will find the correct interface description. Other PLCs have also Add-On modules with standard ports RS232/RS485/RS422.

Regards...

 

[techie]

so is there an addon module for siemens plc. Also, about the interface on the siemens plc. Is it proprietry, or can we hack into it.

 

[Mr_Programmer]

the company process informatik makes a lot of this stuff, you can find them under www.process-informatik.de (but this is only in german)
For the S5 from Siemens the interface is TTY/20mA, for the S7 the interface is called MPI/PPI, but I have no informations to convert this to RS232, Process Informatik offers cables and they work well!

BTW: I have no relationsship with Process Informatik, I'm only a user of their products.

It exists also software components for windows to communicate with PLCs, one software is LUCA Tools.

Cheers...