Guralp Systems CMG-DM24 - Manual (Page 75)

Operator's guide
CENTRE
Syntax: CENTRE or CENTER MONITOR
Centres the sensor mass(es) of the instrument connected to SENSOR A.
CENTRE returns immediately, whilst CENTRE MONITOR monitors the
progress of the unlock by displaying mass positions, as for LOCK
MONITOR (above).
When the masses are correctly centred, the mass positions should read
less than ±1000 counts.
MASSES?
Syntax: MASSES?
Begins reporting the current mass positions for all three components,
once per second, until you press a key. Mass position information is
also output on Mux channels M8, M9 and MA, if you have enabled
them.
Over time, and especially if the temperature changes significantly, the
sensor masses may drift off centre. If this is not corrected, velocity
output will eventually be lost.
%AUTO-CENTRE
Syntax: distance %AUTO-CENTRE
Instructs the DM24 to perform a round of centring whenever a mass
position drifts further than distance from zero. distance is
measured as a percentage of full scale.
Setting distance to zero disables automatic centring.
O/SNULL
Syntax: component value O/SNULL
Remove any DC offsets in a stream by applying a counter-offset in
software. As manufactured, for technical reasons, the ADC offset is set
to around 75000 counts. You should only need to change this if the
digitizer's CMOS RAM becomes corrupted; it is always better to zero
the instrument by levelling and centring as far as is possible, or by
adjusting potentiometers in sensors (where these are present).
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