I have a cDAQ 9178 chassis and both an NI-9211 and NI-9210 thermocouple cards. I have a metal block that I am heating with a 120V AC resistive heating strip modulated by a solid state relay. If I have the heating strip connected to 120V but the solid state relay is off, (so no power is flowing though the heater) and I touch the thermocouple to the metal bock, the room temperature reading from either the 9211 or the 9210 goes from 20C to ~40C. If I add 10k ohm bias resistors to both the positive and negative thermocouple wires and connect the resistors to earth ground the temperature will read correctly. This is frustrating because every other temperature measuring device I have tried (cheap temp logger, multimeter, or thermocouple thermometer) has worked just fine. Is there a way to get the correct temperature measurement without attaching bias resistors to every thermocouple wire? It seems really dumb that the expensive NI daq chassis and thermocouple card are worse at measuring temperature than any other piece of hardware available.
