SCADA_Dude
Member
Does anyone use pullup resistors for PLC inputs? Is an open contact a reliable logic zero as opposed to a grounded input?
I only ask because I have seen some old solid state devices that would pick up stray voltage and actually toggle from nearby inputs with voltage (DGH modules). Using pullup resistors made a reliable input bacause the input was grounded through the resistor when the contact opened.
I only ask because I have seen some old solid state devices that would pick up stray voltage and actually toggle from nearby inputs with voltage (DGH modules). Using pullup resistors made a reliable input bacause the input was grounded through the resistor when the contact opened.