Siemens S7 300 wire break

I have a S7-300 project with a lot of analog I/O and I would like to figure out how to set a bit in my PLC that I can use to trigger an alarm to my WinCC project that specifies the fact that a given channel has wire break, out of range etc. Cant find much specific info in the help files or documentation. Any quick, easy suggestions please?

I have programmed FB 125 in my project and WinCC, but I dont see how to use it to detect analog channel errors to set a bit. I also have implemented SFC 51 to create an alarm stating that a profibus remote I/O node has failed.

Regards,
Debbie

As human beings, our greatness lies not so much in being able to remake the world... as in being able to remake ourselves. -Mahatma Gandhi

I also just read in the FB125 help files that you cant have FB125 and SFC51 in the same project??!! What the hey?!

Debbie

Debbie


What analogue modules are you using? Some are capable of detecting wire breaks, there is a check box for detecting wire breaks in the hardware setup.

I also just read in the FB125 help files that you cant have FB125 and SFC51 in the same project?

Click to expand...

I think you will find that FB125 uses SFC51 itself, that is probably the reason why, then again why would you want to use SFC51 if you are using FB125? FB125 does all that SFC51 does and more.

Paul

You may find that if you read the periphal input, if it is the same as the old S5, the lower 3 bits of the 16 bit word contain info on wire break etc. if set on the card.

Bit 0 = overflow
Bit 1 = Fault bit (open circuit)
Bit 2 = Activity bit (single scan only)
as I said above this is for S5, on that system you always shift right 3 places to get true analog reading, it may be the same on s7

And then again it may not

Being serious, forget S5 advice. It has nothing to do with S7. For any S7 modules capable of generating diagnostic data (digitals and analogues) you normally find that the part number is something like 6ES7-331-9PQ01 as opposed to 6ES7-331-9PQ00 - the 00's have limited diagnostic ability but are much cheaper.

As Paul said, if your modules are capable of wire-break detection, then you simply enable this in the Hardware Configuration. This will generate a trigger to run the corresponding Error Interrupt OB (working from memory here, OB40?). Inside OB40 you can write code to extract from the module's data record exactly which module caused the trip, which channel, etc etc

As usual with Siemens the trigger is dead easy, but they leave it entirely up to you to decide what you do when that trigger is pulled.

regards

Ken