Update your THM1176 to the latest shipping firmware version.
This firmware update is applicable to all Metrolab THM1176 3-axis Hall magnetometers. The current firmware version is the last piece of information returned by the *IDN? command, also displayed under "Info" on the Setup pane of the THM1176 software (later units show the version of the electronics, probe and firmware). Some early units cannot be updated by this patch; these have to be returned to Metrolab for a free-of-charge recalibration. The updater will tell you if this is the case.
The most important changes are to fix a bug whereby the sign was reversed on all three axes, and to provide the capability to better correct for sensor nonlinearities.
Instructions: