[MCC USB-2408-2AO thermocouple noisy signal]

A USB 2408-2AO is configured for seven Type J thermocouples as diffwerential signals on channels 0 to 6 and a 0-5V analog single ended input on Ch7.  With thermocouples connected to the instrument on panel mounted jacks and dangling in air the values displayed are within a degree and steady over time.  The thermouples are stainless steel armored TCs with ungrounded junctions. The TCs tips are sgnetecured to a small aluminum block which is within a horseshoe magnet.  When the magnetic TC assembly is attached to the surface of a heated steel platen on a plastics molding machine all TC values swing wildly and stabilze once again when removed.  We have a strong grounded pwer supply to the instrument.  Is their an isolation/suppression DIN rail module that can restore signal integrity?  What else should we pursue?

[USB-2408 for mixedThermocouple and Analog input noise]

With 8 differential or 16 single ended channels available, my device is measuring seven Type J thermocouples and one analog 0 to 5V signal which is an output from a strain gauge process meter (2 wire output).  The seven TCs are differential.  The remaining two channels are currently configured as single ended channels.  The positive lead of the analog output from the meter is connected to one SE channel and the negative lead is connected to analog ground.  The result is noise on all TC channels.  Please confirm the preferred connection and configuration.  The user guide describes the differential connection with a 100Kohm resistor between the channel low and analog ground.