Guralp Systems CMG-5TD User Manual
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Operation
If you expect breaks in communication between the instrument and its client
to last more than 256 blocks, or if you want the instrument to handle breaks
in transmission (rather than relying on the client to request missed blocks),
you should use
•
ADAPTIVE mode, if you want data to stay as near to real time as
possible (but do not mind if blocks are received out of order) or
•
FIFO mode, if you need blocks to be received in strict order (but do not
mind if the instrument takes a while to catch up to real time.)
5.9.5.2 DUPLICATE
Instructs the DM24 to transmit streams directly to clients as for DIRECT
mode, but also to store all data into Flash storage as for FILING mode. If a
client fails to acknowledge a block, the digitizer does not attempt to retransmit
it.
Heartbeat messages are not sent in DUPLICATE mode.
5.9.5.3 FILING
Instructs the digitizer not to transmit blocks to clients automatically, but to
store all digitized data in the Flash memory. If you have chosen the RECYCLE
buffering mode (see below), the memory is used in circular fashion, i.e. if it
becomes full, incoming blocks begin overwriting the oldest in memory. If the
WRITE-ONCE mode is active, the instrument will switch to DIRECT mode (see
above) when the memory becomes full.
Heartbeat messages
When in FILING mode, an instrument transmits “heartbeat” messages over its
data port. These short messages take the place of data blocks, and ensure that
programs such as Scream! know that an instrument is present.
If your digitizer is in FILING mode, Scream! will displays a slider at the
bottom of the tab. Moving this slider changes the interval between heartbeat
blocks.
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Issue D - April 2013