Xterri

Not an electronics buff, so I need some basic help... I have a PLC which does not have mechanical relay outputs. Therefore, I am assuming that it has solid state relays for output. Few of the outputs are connected to LED lights. However, these LED lights are lit, even though the outputs on the PLC are in the OFF state. I'm assuming that there is voltage leakage through the SSRs. How do you resolve this situation? Would adding a parallel resistor on the same output help? Any other techniques to resolve this phenomenan? Thanks

Hello, I've got an old PLC which does not come with any PID loop capability. Trying to control a small heater (nothing critical), but in the absence of an PID controller in the CPU I must write a "pseudo", time-controlled PID. Does anyone have a sample code to accomplish this? What I have in mind is a time/percentage controlled feature, where as the temperature gets closer to the set point the heater turns on less time, etc. Thanks.