CMG-3V
5.2 The control system
The internal operations of the 3V are supervised by a control
microprocessor, which drives the mass clamping and centring
adjustment motors. It responds to commands sent on three input lines
by grounding for 0.2 – 7 seconds.
The signals you can send to the microprocessor are termed
LOCK
,
UNLOCK
, and
CENTRE
. The microprocessor prevents the system from
aiempting i ncompatible a ctions (
e.g.
centring when the mass is
clamped.)
While a command is taking place, the
BUSY
LED will fash; you can use
this for diagnostic purposes. See the description of each command for
full details.
When no command is active,
i.e.
all three lines are high, the control
microprocessor goes into a power-saving mode. In routine operation,
the lines are controlled from the breakout box, Handheld Control Unit
or digitizer. If you send control signals to the 3V manually, you must
ensure that the lines are pulled high afer sending the signal, or the
equipment may be damaged. A “biased-OFF” type switch can be used
for this purpose.
LOCK
This command unlocks the mass.
If
LOCK
is activated when the mass is already locked, the processor will
unlock it and aiempt to lock again. This is useful if you suspect that the
locking procedure has failed.
The process comprises locking the sensor mass, followed by a longer
period tilting the sensor base to its end stop.
The
BUSY
LED is lit during each stage, but goes out briefy between
stages, allowing you to follow the progress of the lock.
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