Omron C500-PS222 PLC I/O power supply

There is more to a PLC power supply then just its output voltages. They also send a TTL level signal to the CPU module that tells the CPU the health of the power supply.

If that signal is not present, the CPU may module may power up, if the proper voltages are present, but not execute its programminf because it does nor see the power supply as being good to go.

Thank you for your information it's usefull for me, can you tell me what kind of TTL singnal and the frequency? the current condition, it's coming out TTL signal (square pulse 1,1volt , 100Hz) but i'm not sure if it's correct or not.

Power supply verification at the start up is a very good idea and almost every good design must use it. There is somewhat difficulty in mid way crashing of the power supplies and then abruptly truncating the working of the PLC and LOGIC controllers.

Short circuit protection also to be monitored for I/O and need to be used as information to at least give warning and divert the program from safety point of view.

I think you have pointed out very important parameter about PLC power safety scheme so you get a plus for it.

I have found the answer of this power supply problem, i also bring the answer to this thread as information for any body that maybe have same problem with me, this power supply output are + 5vdc, +24vdc and a sinusoidal pulse 340mv p-p ( no load ) with +/- 170 kHz frequency.