pc/ppi cable

just wondering if i am correct in assuming that the connections for a pc/ppi cable are 1 - 1 , 2 - 3 , 3 - 2 , 4 - 4 , 5 - 5 , 6 - 6 , 7 - 8 , 8 - 7 , and 9 - 9 ?????

IF I am not mistaken the PPI interface is an RS232 to RS485 converter that has different switches for different versions of software. I dont think you can make a cable that will allow direct access from the PC to the PLC.

I have an MPI/Profibus adapter so not sure of all the differences but do believe that all the 9 pin connectors on Siemens S7 are RS485 and the S5 needed a TTY converter.

You should look into using MPI because it allows you to connect to multiple controllers and devices. I think PPI only allows a connection to one device.

My info may not be accurate but you can go to the Siemens support site and look for the information...GO HERE

RSDoran,

you're correct when you say all 9-pin connectors on S7 are indeed RS485.

On S7-200 they're restricted to 19200 baud, with a standard setting of 9600 baud. These are called PPI or Point-to-Point-Interface. The swithes on the side of the PC/PPI interface are for setting the baud rate. This converter is a simple data-controlled transparant RS232/485 converter. There should be other interfaces around to do the job, but don't expect any help from Siemens if something goes wrong while you're using a non-Siemens interface.

The standard for the S7-300/400 is called MPI or Multi-Point-Interface. Here the standard baudrate is 187,500 or 187k5. An MPI interface is NOT simply an RS232/485 converter, but it uses speed conversion as well as protocol conversion. Don't try to use any other interface unless the manufacturer gives it in writing his interface is Siemens compliant.

It's possible with both interfaces to get connections with more than one PLC (iow both can act as multi-point interfaces), but at 9600 baud I would not recommend it.

Kind regards,

just wondering if i am correct in assuming that the connections for a pc/ppi cable are 1 - 1 , 2 - 3 , 3 - 2 , 4 - 4 , 5 - 5 , 6 - 6 , 7 - 8 , 8 - 7 , and 9 - 9 ?????

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crashup,

DO NOT CONNECT THAT CABLE. If you do there's a fat chance you'll damage the PLC, the PC or even both. The only thing you would end up with is the first part of your username.

Kind regards,