Hi all,
We have some problems with a relais board, connected to the NI 9403. Probably we need some pull-ups for proper definition of the outputs during initialization of the 9403 (a logic high switches off the relais).
After powering the 9403, no relais are activated, which is good. So the input terminal default has no consequence.
However, directly after starting the DO task defining the 9403 as outputs (without writing actual data yet), all relais are activated. This behavior is independent of the 'InvertLines' property and thus independent of the default logic level.
My question: what happens with the terminal type (and input impedance) during power-on and directly after starting the DO task? Does it change to a tri-state situation? And does it leave the tri-state after writing the first data word?
Can we resolve this by adding 4k7 pullup's to the terminals?
Thanks for helping!
Martin