6. Operation
Projekt Elektronik
MESS - UND REGELUNGSTECHNIK GMBH
Page 26
Figure 12 Display error message offset out of range
To reset the compensation to zero, the key “zero” has to be pressed a
second time while the compensation process is running. The FM 302
confirms the reset of the compensation with the message “reset zero to
midscale”.
Figure 13 Display reset offset compensation
There are two possibilities to compensate the zero point.
•
At the AS-UAP probes in the less sensitive range and all other AS-
probes in the most sensitive range and measuring mode DC the
measuring direction of the probe is positioned orthogonal to the earth
magnetic field in east-west direction. With the “zero” key a compensation
of the zero point is performed. Afterwards the probe should show the
same value only differing in the sign if aligned in north-south and south-
north direction. The typical value of the earth magnetic field in the area of
Europe is 30 µT to 50 µT.
•
If a zero chamber is at hand after inserting the probe the offset
compensation can be performed by pressing the “zero” key.
The offset compensation is an additive correction which doesn’t have an
impact on the linearity.
See also section 6.3.3.24 Command “zero” for controlling the offset
compensation via the USB interface.