Communicating in RS232 or 485 with S7

Hi

I have to control some servo motors via an S7 PLC. The servo motors need to be given various control 'words' via an RS232 or RS485 serial interface.

Does anyone know how I go about this with an S7 300 series PLC. Do I need a special serial comms card or can I talk to them from the MPI port? If its possible via the MPI port, do I need some sort of MPI to serial interface??

Also, does anyone know if I need to include some special function blocks in the software to achieve this?

In fact.. any information at all that anyone has on setting something like this up would be very much appreciated.

Thanks for any help you can give me

JT

Hi JT,

Have a look at "communication processor" CP340/341 both support (depending on which model!) RS232/485. There are canned Function blocks available for use with these modules:

FB2 P_RCV - RECIEVE DATA AND STORE IN DB
FB3 P_SEND - SEND ALL/PART OF A DB

hope this helps to get you started mate

Steve.

Stevo

Thanks for the tip mate. Will order a comms processor and see how I get on.

Thanks again..

JT

CP340 Manual link:

http://xbci.com/FordSpecifications22Nov04/cp340_e.pdf

covers all types & those FB's

Only done ASCII transfer via RS232, But im sure the Resident Gurus will sort you out.

all the best
Steve

Stevo is right. And I believe the 340 card is much cheaper (double-check me on that though) and will be fine unless really high speeds are necessary.

I've done a ton of comm stuff with the 340/341s, and can give you help once you get started.

Stevo, thanks for the link, downloaded the manual now.

S7Guy, many thanks for the offer of help. I'll be ordering the 340 card tomorrow and then cracking on with the software on Monday. I can say categorically now that I will definitely be taking you up on your offer of help

Brilliant!

Thanks again

JT