Hi All,

I am trying to program an S7200 PLC, but have run into many headaches!

While I am very confident in myself with S5 and S7 (300/400), I know that even the simplest code I write for the higher end systems does not work in the S7200, like a "flip flop" or "toggle" for instance and requires a work around.

I am trying to use one push button to control two auto routines based on the status on one flag that is on or off but it fails to work.

I have tried many things that I know will work in the higher end systems but it will not work in S7200. I see in the help manual that the S7200 seems to work with a stack where I have never seen this in all my years of working with the higher end systems.

What is the quickest way to learn the intricacies of this system or some ideas to accomplish what should be relatively simple tasks to solve?

Dan

 

I have programmed a number of S7-200 units. They seem very similar to other units in the way they program, at least for ladder logic, which is all I have used.

--
Bob
http://ilbob.blogspot.com/

 

After two days of banging my head I am close to having a working machine!

The problem with my two subroutines seems to be a problem with the update of the M memory. My second subroutine was basically copied from the first with some minor changes. It seems to me the problem should exist in the first subroutine but doesn't some how. But the flag that calls the subroutine is reset as the last step in the subroutine. When this flag is set to run another machine cycle, it was immediately reset and appeared to never even come on. Looking at the status chart, none of the flags were set that were used in the subroutine. The decision to reset the problem flag was set and reset in the same scan, but adding a time delay to run more scans between the set and reset seems to have fixed the problem. I have never seen this in the higher end Siemens systems!

Thanks for the reply!
Dan