Guralp Systems Scream - Manual (Page 97)

User guide
8.5.4 DUAL
Instructs the digitiser to transmit any continuous streams directly to
clients as for DIRECT mode, but to store triggered data into Flash
storage as for FILING mode.
If you choose DUAL mode but do not select any continuous streams for
output, the instrument will send heartbeat messages as for FILING
mode. Scream! can pick these up and download new data as
necessary.
8.5.5 FIFO (First In First Out)
Instructs the digitiser to begin writing blocks to Flash memory as for
FILING mode, but also to transmit data to clients. Data are transmitted
in strict order, oldest first; the digitiser will only transmit the next
block when it receives an explicit acknowledgement of the previous
block.
If the communications link is only marginally faster than the data rate,
it will take some time to catch up with the real-time data after an
outage. If you want data to be transmitted in real-time where possible,
but are worried about possible breaks in communication, you should
use ADAPTIVE mode instead.
FIFO mode will consider a data block successfully transmitted once it
has received an acknowledgement from the next device in the chain.
If there are several devices between you and the instrument, you will
need to set up the transmission mode for each device (if applicable) to
ensure that data flow works the way you expect.
Like all the transmission modes, FIFO mode does not delete data once
it has been transmitted. You can still request anything in the Flash
memory using Scream! or over the command line. The only way data
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