435x Thermistor Cable Length

[geirove]

Hello,

I am trying to find out the Maximum length a cable connected to e.g. a Thermistor using 4 wire connections may have.

My hardware will be a PXI box running RTOS (VxWorks). I have found a DAQ card called PXI-4351 but I am not sure if it is old, since I cannot find it listed under DAQ devices on the PXI pages (!). I may also need the TBX-68T terminal block.

The distance between the PXI Box and the Thermistor will be approx 100 meter (300 feet). I will use a shielded cable and 4 wire connections. I have searched all over the inernet for 2 days, but am unable to find if this measurment can be done over 100 meter (300 feet) cables without using an amplifier at the sensor end. I will require about 0.5 degrees accuracy, but will the Noise Levels be acceptable when using the filtering capabilities of the board. Sample rate is low: Only approx 1 sample a minute.

I appreciate all the help I can get !

[geirove]

Hello,

Here is a figure showing a diagram of what we want to do:

We want to connect 12 Thermistors (or RTDs or Thermocouples)  using 3 or 4 wire connections.

We will run RT (ETS) on the PXI box.

Our quesions are:

a) Will the PXI-4351 board be able to support cable lengths of e.g. 130 meters, and what will the signal quality typically be?

b) Any newer board than the PXI-4351 that is better suited for the task?

Would anyone at NI be able to provide any help please?

Message Edited by geirove on 06-15-2008 10:11 AM

[geirove]

Hello,

Is no-one at any able to help here?

I activated "Talk to an expert" that promised that someone would answer within two days, but nothing happens?

I talked to the NI dealer in Norway, and they reported back: "No feedback fromNI".

Since NI designed and sells the board, there ought to be someone at NI that can help?

Not easy to try to use NI hardware in an industrial project with no support from NI !