3 setting up external triggering – Guralp Systems CMG-DM24 User Manual
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Operator's guide
Loading a new boot loader
There is only one slot available for the boot loader. Press B at the
maintenance menu to update it.
The digitizer will then request a transfer using the Xmodem protocol,
as described above. Be sure to check beforehand that the file is a valid
DM24 boot loader! Replacing the boot loader with invalid code will
make it impossible to boot up the digitizer. If in any doubt, please
contact G
ü
ralp Systems technical support for advice before
proceeding.
When you are returned to the maintenance menu, press Q or wait 30
seconds for the system to restart.
6.3 Setting up external triggering
Güralp digitizers and digital instruments can be supplied with external
triggering capabilities installed. The external trigger system is designed
for maximum flexibility: you can trigger other digitizers or your own
equipment using built-in relays, or any equipment may be used as a
trigger source. In addition, a trigger circuit can link together any
number of digitizers so that they trigger simultaneously when they
receive a signal.
Overview
The digitizer or digital instrument has two internal components
related to triggering.
•
The trigger generator runs the triggering algorithm and
determines whether a trigger has occurred. If external trigger
output has been enabled, the trigger generator also operates a
relay which connects the two Trigger Out pins of the DATA OUT
port. These are normally pins E and F.
The Trigger Out pins are only connected whilst the generator is
active. This does not include any pre-trigger or post-trigger
period, which is dealt with by the trigger receiver. A trigger
signal may be as short as one second.
•
The trigger receiver acts upon trigger signals: normally, by
recording additional data streams. The receiver will always start
recording if the trigger generator produces a signal. If external
trigger input has been enabled, the receiver will also act on a
logic signal received on the Trigger In pin of the DATA OUT port.
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