S7-313C - Input/Output problem

Hi Guys,

This is a very basic question for experienced Siemens programmers (normally I program Mitsubishi PLC's). We have a Siemens 313C-2DP CPU with integrated Inputs/Outputs (DI16/DO16). When I create a project I see that the inputs are assigned IB124/125 and QB124/125.

The problem is that I want to monitor one of these inputs (using a VAT-object). If I set the input (using 24 V on the input pin) the LED is lit. However, when I monitor I124.0 (or IB124) the change of the input is not detected. What am I doing wrong?

Any suggestions are greatly appreciated!

Thanks

Hi!

You haven´t forgot to wire the terminal ground, 0V on the cards terminal?

Hi Weo,

No, M is connected from the power supply to M on the card. The LED is lit so it seems to be OK, or?

Any other suggestions?

1. Open HW config in online and look to IO.
2. I amn't sure but it seems I had similar problem some years ago. I amn't sure can be input visible as Ix.y if it's assigned to positioning or counting. Unfortunately, I cann't remember now details.

Any other suggestions?

Thanks

//Supporter

What do you see in HW online monitor/modify? There you can see physical input status. Did you applied 24V to another inputs belonging to this PIB?

Did you click the 'glasses' button to go online? The status window should strobe green and read online or something similar.

Right click to your DI24/DO16 in online HW config. Select Monitor/Modify. You can see PIB state when I/O display is checked.