Siemens: inputs not working

When inputs from Factory I/O don’t work you probably need to make sure the input addresses used by Factory I/O are not shared with physical inputs.

Input signals with intermittent / blinking behavior is usually caused by interference between physical inputs of the PLC with inputs from Factory I/O sharing the same address. Values transmitted by Factory I/O are being overwritten by the values of the I/O modules as their state is copied to the CPU process image, which will cause blinking/the impression that inputs from Factory I/O don’t work.

You can solve this in two ways:

Use different addresses

You can either use different input addresses in Factory I/O by changing the Offset in the driver configuration window:

Or change the addresses used by input modules, leaving addresses near 0 free to be used by Factory I/O:

Set the module PI to none

You should do this for every input module of the PLC, either digital or analog.

You can also refer to step-by-step guides on how to connect Factory I/O to various Siemens PLCs.


Hi @brunovgr,
since we have to give an offset everytime, does this mean that we can’t work with the modules that are present on the hardware configuration ?

You can work with the modules, but Factory IO can’t set or force the inputs on a IO module, even during simulation.
As a result, inputs from modules that have the same address as inputs from Factory IO will conflict, overwriting each other.

Are you referreing to modules that have both inputs and outputs in this case ?
so if i understand correctly we can put them (Modules) in the hardware configuration but not use their addresses right ?

Problem is that physical IO has “priority”. For Siemens Factory I/O would use PUT/GET top write to I/O addresses. But if those addresses are already used by physical hardware they will get overwritten.
What is possible tho IIRC is when you have configured the physical hardware but not connected it to the PLC, because that way the PLC will not get a signal that is overwriting the I/O.


Sorry for reopen the thread, but I have the same problem and any tips I read has solved my problem.

I tried to connect with PLCSIM, a PLC 1212C. The Input address start at byte 10.0 and Outputs in byte 0.0. I have a expansion target, a signal board of 4 digital inputs. This start in byte 13.0

I use System and clock memory, but I think this not have effect in this problem. I have the HSC1 (High Speed Counter) enabled, but I try to disabled it and any changed.

I need something more? any configuration I passed out?

I use TIA PORTA v17 and Factory I/O v2.5.1