Siemens S7

Hello Everyone, Still learning the ropes to S7. I had trouble with a machine and couldn't find the fault in the program. I spoke with the maker of the machine and he told me which input to look at and which wire to jump. I still couldn't find the input on my PC. What must I do to See the entire program. I did a compare and it didn't show any difference in the program other than registers or numbers. any help would be greatly appreciated.

What S7?? Can you post the program, then tell us what they said we can help you look for it...

I can help if its an S7-200 and others will help if its a 300 or 400

sorry it is 300.

I am not sure what level you are at, so at a basic level:

1, Siemens uses a system of individual blocks of code called from OB1. Generally, you cannot see the entire program, only 1 block at a time. The exception is if you generate source code. In that case you get the entire program in one text file in STL (assembly) format.

2, to do a basic search, you need to have opened a block and you can either go to Edit->Find/Replace for addresses or text within the block, Edit->Goto->Location for addresses anywhere (although you have to have highlighted an address to use this option) or, Options->Reference Data->Display. With this final option, you select cross reference, and filter for inputs. You will be able to find the location of all the inputs in the code by this method.

3, Tricks. I have found that for some reason a lot of German companies like to use indirect addressing, and move all their inputs into the DB range. Unfortunately, this makes finding the input impossible through the search functions. By this method, a pointer to an address is assembled and this is used to move the contents of the input registers over. It is generally done in STL, and can usually be found by looking for the shift left function. The easiest way I found to look for this is to generate the entire program in source code, open it with the text editor, and search for the shift left function, or variables of the type pointer.

Hopefully they did not use this method.

Doug

You mention finding a certain input to "jump a certain wire" you can find which input is which through the Hardware Config. If you open your project in Simatic Manager and click on the PLC on the left. Then open "hardware". Then you can see the order of the modules on the rack and what inputs/outputs are assigned to each one. This will allow you to track an input or output in the real world.

Not sure if this is also what you were asking...?

Hope that helps

uptown47 said:

You mention finding a certain input to "jump a certain wire" you can find which input is which through the Hardware Config.

Click to expand...

You can also usually find it in a panel.

Don't you have the schematics?