BobP (Customer) asked a question.
What is the minimum current required for a voltage input?
Using F4-08AD in the 0-10 volts range. Card works perfect with voltage generator supplying 10 volts with ~30mA. Customer device is 10 volts at ~20 mA and when this is applied, the voltage at the input cuts in half. Problem is repeatable on multiple cards. What is the minimum required current for the 0-10 VDC signal?
Thank you.
That card has a 20M ohm voltage input impedance so not much at all. Have you verified it's actually 10V on the input terminals when connected to the card?
It is clearly 10 volts when disconnected but drops approximatel in half when connected. Using Voltage generator, if I limit current, I can get similar results but I can not control the current limit precise enough. exact same result on two cards in two different PLCs at the site.
Hey Bob what device is it if you can say? Is there a part#?
The PLC is a D4-454. the analog input card is the F4-08AD.
Sorry I mean't the device outputting the signal
The device is a gas analyzer that we are interfacing with.
That card has jumpers for each channel to select current or voltage inputs. If those jumpers are installed (I think that's the default) then the channels are expecting a milliamp input and will only have a 250 Ohm impedance.