Stairstepping in thermocouple data with TC-2095/SCXI 1102c

[xander c]

Here's my setup:

32 K-type thermocouples (mixture of grounded sheathed and ungrounded exposed tip)

TC-2095 rack mount thermocouple connector block

SCXI 1102c module

I am having an issue of stairstepping in the thermocouple data I am getting.  The system seems to be sampling at the 500-1000 Hz sampling rate because noise and gentle sloping is recorded in the tc data in between the major jumps in temperature.  The stairsteps generally occur at 1 or 2 Hz.  The only thing I modified on the hardware was swapping in the 10 Mohm resistor packs into the tc-2095 to prevent a grounding issue from ruining the readings from our grounded thermocouples.  Any thoughts on how to fix the stairstepping?

Thanks,

Alex

[CharlesD]

Hey,

Did this work without the10Mohm resistor pack?? Did this ever work?  

You say you have grounded thermocouples---what are they grounded to?  Can you expand on this setup.

How did you configure the dip switches on the TC-2095 for each thermocouple? I'm referencing the settings mentioned in table1 of the tc-2095 specifications sheet.  This is found on page 5-6 of thespecs manual: http://www.ni.com/pdf/manuals/321731b.pdf

Can you attach a screenshot of the data that you are seeing so that I can inspect it.  Also what sampling rates are you specifying?  how are you programing this (Labwindows/labview?? etc... )

Please post back with this info so we can work to resolve this issue thank u