The plot I attached and didn't explain is:

• Green = Voltage across the Ohm Ranger as driven and read out by the (unknown) bridge of the Newport 3040
• Red = Voltage across a high power 5 Ohm resistor I am using on the current output of the Newport 3040
• Units are standard DAQ conversion ~ 1600 counts / Volt

Notes:

• I use an SR560 to buffer the signal from the ohm ranger before inputting it into the AA chassis
• The resistance between the inner BNC leads of the AA box was ~2 kOhms - FOR SEVERAL DIFFERENT CHANNELS
• I have the PI (no D) servo set at its lowest settings, so lowest integral gain, and lowest proportional gain.
• I make step responses in the green curve via the ohm ranger.
• I should see step responses of the red from the proportional term, and changes in the slope of the integration following these step responses.
• I see SLOPE IN THE GREEN. This is weird.
• The slope in the green goes away when I unplug the voltage (from the TEC drive current) across the 5 ohm resistor from the front end.
• The slope in the green stops when the current rails.
• I don't understand the coupling, but since I don't have circuit diagrams for the 3040 - I stopped thinking about it, and just used a USB stick in a scope to take this data.

Moral:

• The 3040/ front end acts funny when you try to read out the current and the voltage of the thermometer.
• I don't really care that this is the case.
• The front end seems to be working close to all the way