Hi everybody,

I have replaced a faulty S5-95U 8MC01 (with 2 serial ports) with S5-95U 8MA04. There was an OP7 connected on the second serial port, and since 8MA04 doesn't have a second serial port I have connected the OP7 to the PG port of 8MA04. The system doesn't.

My questions:
1. Is it possible to replace 8MC01 with 8MA04 if only one serial port is being used.
2. How do I configure PLC/OP?
3. What problems I might encounter? (Note: I have a PG720 to do programming)
4. Is it safe to do so?

I would appreciate if anyone could be of any help.

Thanks,

bagi

 

If I recall correctly, you may need to use a different FB for the OP communications. If you were using FAP via SI2, then you would use FB53. If you are using AS511 via the PG port, then you would use FB51. Note that if you have to replace the FB, it must be with one for that model of PLC (i.e. use one intended for an S5-95U, not one meant for an S5-135).

If you were using SI2 with the FAP protocol, then you would have called the FB53 with something like the following:

L KY53, 1
JU FB53

If you were using the PG port with AS511, it would look like:

L KY51, 0
JU FB51

Note that the KY53 and KY51 in the above examples may not match your actual program. These are the interface DB numbers, which need to match whatever DBs were used for this in your program (most people like to have the FB and DB numbers match though). If I recall correctly though, the 0 and 1 indicate the port numbers.

I have used a lot of S5-95U PLCs, and most of them had OPs (including the OP7) connected to the PG port. One problem with the OP7 is that it doesn't have loop-through mode, so you have to unplug it from the PG port to program the PLC.