Reading the same voltage with 2 different devices

[RWiemann]

Hi I have a pressure transducer that I need to have 2 seperate devices read from continuousely. This is a 0-10V analog output signal. One system will be sampling at around 10Hz the other will sample around 1-10kHz. Both are differential analog inputs.

Will there be issues if I do this?

Will I get inaccurate measurements?

Do the voltage measurement devices affect each others measurements?

Thanks. An explaination either way would be much appreciated.

-Rym

[Dennis_Knutson]

You can certainly have two different DAQ devices running at the same time and neither will affect the other. You can also use a single device with the same sample rate. You would just decimate the results from the one you wanted at the lower sample rate.

[RWiemann]

This signal is going to two seperate devices so sampling once then pulling out every 100th sample would not work but I understand. So do you see any advantage or disadvantage to converting to 4-20mA and then measure across a precision resistor, besides the obvious of extra hardware and added labor? Thanks.

[Dennis_Knutson]

Quite frankly, I don't see any point in using two devices or two channels.

[FCTesting]

Depending on your hardware and application it could have both advantages and disadvantages. In general, adding more equipment can compound error (such as the error in the precision resistor and/or power supplies). However, for very long wire lengths current can be advantagous.

Some good ref. info on how to decide what is appropriate:

Five Tips to Reduce Measurement Noise

http://zone.ni.com/devzone/cda/pub/p/id/262#toc3

Measuring Current with an Analog Voltage Input

http://digital.ni.com/public.nsf/allkb/82508CD693197EA68625629700677B70

Also whether you have current measurment modules is an important consideration (vs. using a precision resistor).

[RWiemann]

The reason I need to use 2 devices is I need the signal for a PID loop in a VFD (Device #1) and then I am using a PXI (Device #2) to record the pressure at 1kHz.