NI 6584 Constant High

[bchang32]

Hello, I am trying to use the NI 6584 to read in data from a line. For some reason, when no cable is plugged into the connector, it will always read high. Even when the connector is plugged in, but no values are being fed into it, it will read high. I wanted to think it was active Low, but that doesn't seem to be the case.

When I switch the node from RX0 to PFI (via the BNC connector), it behaves correctly.

Any insight would be appreciated. Thanks 

[Bob_Schor]

You do realize it is meant to be an RS-485 protocol device, don't you?  It sounds like you might be trying to use it in a way for which it wasn't designed (but I don't have a manual for this device, nor do I know your application ...).

Bob Schor

[bchang32]

Yes I am aware it is RS-485. We are plugging a RS485 signal into it which is why I was surprised when we plugged it into the PFI line, it worked correctly (albeit with some connectors and conversions)

Also I did a sanity check vi where i have nothing connected to the pin (even disconnected the connector), and all the indicators turn high. I imagine the module isnt active low?

Update: It appears to be active low. Ran an input high into the aforementioned vi and it turned off the LED