THM1176/TFM1186 Use
r’s Manual
v 2.0 r 1.0
– 02/20
Copyright © 2020 Metrolab Technology SA
www.metrolab.com
13
•
Zero-offset calibration (
not for TFM1186
– see Section 2-6!
):
To guarantee the specified accuracy, the measurement offset should be
checked before each measurement sequence, using the zero-gauss
chamber supplied. If needed, the offset correction procedure will measure
and correct this offset. The correction value is written to flash memory so
that the same correction will be applied the next time the instrument is
powered up.
•
Readout options:
The three field components are always acquired, but the readout can be
limited to any selected components. The readout can include a single
measurement or an entire array of measurements, and can be formatted as
an ASCII message or as a binary block. Binary data may be compressed
by a factor of two or four, for example to help reduce the traffic on a busy
USB hub. Depending on the model, the field values can be returned in
Tesla, mTesla, µTesla, nTesla, Gauss, kGauss, mGauss, equivalent proton
NMR frequency, or raw ADC values. The timestamp (in ns) and sensor
temperature (arbitrary units, not calibrated) can also be read out.
3-5 PROBE MECHANICAL DESIGN
•
Protection for the sensor:
Magnetic sensors are sensitive electronic components. The plastic cover of
the THM1176-MF, -HF and -LF protects their Hall sensors from the bumps
and scrapes of normal use. For the THM1176-MF and -HF, the sensor
packaging provides effective protection even with the cap removed (see
below). However, the THM1176-HFC lacks all such protection; please note
the special handling precautions in Section 2-6, Precautions. The TFM1186
sensor is relatively large and mechanically very robust.
•
Small gaps:
The THM1176-MF, -HF and -LF probes are 10 mm thick. To measure in a
smaller gap, the THM1176-MF or -HF probe cap can be removed, reducing
the thickness to 4.1 mm. If needed, the THM1176-MF or -HF sensor
– only
2.3 mm thick
– can be separated from the probe plastic; note, however,
that the sensor wires are delicate and can easily be broken. For even
smaller gaps, use a THM1176-HFC, whose probe is only 0.5 mm thick.
