NI-9237 (bridge) with external excitation draws 100 mA without bridge connected.

[Thomas@DVel]

Hi,

I have a 9237 with d-sub and wants to use it with external excitation. I connected the full bridge to ex0-, ex0+,ai0-,ai0+ and the external excitation to Vex- and Vex+. I had problem to get the correct voltage and after a while I disconnected the bridge so only the ext. exc. was connected, still problem and I measured the current to be 95 mA from the ext.exc.!

Shall it be like this?

BR

Thomas

[andres.vargas]

Hi there,

That does not seem normal.

According to the External Excitation section on page 6 of the 9237 datasheet the EX+ and EX- pins are only used to daisy chain multiple modules. Are you possitive that you connected this correctly?

Also, make sure to check that your external excitation adjusts to the 2-10 V voltage levels indicated in the datasheet.

And remember that you have to tell the device via software that you are using external excitation, it does not detect it on its own.

[Thomas@DVel · Accepted solution]

Hi,

The problem is solved. The externa power supply is a bit odd and the two outputs (+ and -) were shifted and it seems that the 9237 did not like that.

/thomas