How make a continuity test?

  • Thread starter Eduardo Herrera
  • Start date

Thread Starter

Eduardo Herrera

I have a 12volt power supply , so i have 12v test lead plugged in the "Object to be tested", then with other test lead I return the current (4-20mA) to an analog input module.

i think is dangerous because i can cause a short circuit and damage the analog input module.

Any of you have a suggestion? a better idea?
Thanks for your help.

I run tests on simple diode - microswitch based PCB by treating them like a black box and applying a forward and then reverse DC voltage to each lead one at a time and monitoring all the other leads on descrete PLC inputs that the common and thus card can be configured for pos/neg input. I use a relay tied as to supply the input common with the oposete of the DC supply that I apply to a relay output cards common connection. Apply + to lead # 1 and check all other leads for a positve input, switch the FEW-REV and check in the oposite direction. The bit patern for all leads is compared to what should be right and by also testing with NO lead powered, the PLC I/O is confirmed.

Send e-mail to me and I'll return a AC-14 or bit map diagram.
We do continuity much simpler. But depends on your PLC. Using a source output feeding through your test piece, then into a sink input. These are purely digital outputs and inputs. Protection may be needed for your output(PLC specific).

[email protected]