Hello,
I am experiencing unexplained behavior with a PXIe-6341 card which is being used with a SCB-68A cable.
I have 3 sensors connected as follows:
AI 0 – Pyrometer
AI 1 – Pressure Sensor
AI 2 – Position Sensor
All 3 sensors are connected to the + and – inputs of each channel.
All 3 sensors have a power requirement of 24 volts (powered via a stand-alone PS) and draw 4ma – 20ma.
We have placed a 250 ohm resistor across each channels + and – inputs which results in a voltage measurement of 1 – 5 volts.
When I use the Test Panel feature of NI-Max and individually select each sensor from the pull-down menu – the resulting measured value displayed in the graph is always correct and everything works as expected. This is true every time for each of the 3 sensors.
However, if I create a NI-Max Task in which I try to simultaneously observe all 3 sensors measured data I experience the following behavior:
Scenario 1:
If the task contains just the Pyrometer and the Pressure sensor the measurements are always correct.
If I then add the Position sensor to the task its measured/displayed value is not correct. However, the voltage measured at the 68A + and – terminals is, in fact, correct.
Scenario 2:
If the task contains just the Position sensor the measurement is correct.
If I add either the Pyrometer or the Pressure sensor to the task their measured/displayed values are not correct. Their displayed data equals 0 volts. However, the voltage measured at the68A + and – terminals is, in fact, correct.
I am stumped.
Can anyone shed some light on possible causes of this type of behavior and recommend solutions?
Thank you.