Guralp Systems Scream - Manual (Page 95)

User guide
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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).
8.5.2 FILING
Instructs the digitiser 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 digitiser is in FILING mode, Scream! will displays a slider at the
bottom of the tab. Moving this slider changes the interval between
heartbeat blocks.
You can tell Scream! to download new data automatically whenever it
receives a heartbeat message from an instrument in FILING mode.
This is useful, for example, in autonomous installations connected by
intermittent modem links. To enable this feature:
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