PXI-6229 & SCB-68: Current measurement with low pass filter

[OSU_Nuke]

I'm dedicating a PXI system that uses a PXI-6229 with SCB-68s to measure 4-20 mA current input. We have some high frequency noise in our measurements that we've been unable to clean up except by installing low pass filters. My question is this: The manual for the SCB-68 has instructions on where to solder in the components for current measurement and for the low pass filter, but this would result in the shunt resistor and capacitor both residing in position "E" on the board. I've noticed that there are two sets of solder points at position E. Do I just use these two pints and install the shunt resistor and the capacitor in parallel at position E? I'd like to avoid having to install one of the components across the AI screw terminals if possible.

[Esteban.R]

Hi OSU_Nuke

Could you describe me a little more what exactly is what you want to do?  I have not fully understood your question.

Have you thought about using a digital filter in LabVIEW ?

Regards

Esteban R.

[OSU_Nuke]

I'm trying to measure current using a PXI-6229, which requires configuring differential analog inputs and installing a shunt resistor across the input on the SCB-68. However, I also want to install a low pass filter across the inputs to eliminate signal noise that we haven't been able to run down. In the SCB-68 manual the shunt resistor for current measurement and the capacitor in the low pass filter are both supposed to be installed in "position E" on the board. This precludes installing both a shunt resistor and a low pass filter, as there is onlt 1 set of solder points at position E.

I can just install the capacitor across the screw terminals of the SCB-68 to get around this, but I'd like to avoid that in case the system wiring is ever changed to make it harder for someone to put back together incorrectly.

I haven't looked into using a digital filter in LabVIEW, but that is probably not a possibility. Our system software was professionally developed and has been dedicated. It is configuration managed and would mean a lot of paperwork and time invested even to get to the point of having the software change approved for implementation.

[Esteban.R]

Hi OSU-Nuke

I am looking at the figure 4-19 of the page 4-18 of the SCB-68 User Manual for Advanced Functions and it actually has more than 1 ser of solder points at the position E.

I hope that this answer your question if it does not please attach a picture of how you want to connect the filter and the shunt resistor.

Regards

Esteban R.