Guralp Systems CMG-CD24 - Manual (Page 44)

CMG-CD24
Instructs the CD24 to transmit streams directly to clients as well as
storing all data into Flash storage as for FILING mode.
A digitiser in DIRECT mode still honours the GCF Block Recovery
Protocol: a temporary RAM buffer always holds the last 256 blocks
generated, and if a client fails to receive a block it can request its
retransmission.
If you expect breaks in communication between the digitiser and its
client to last more than 256 blocks, or if you want the digitiser 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 digitiser takes a while to catch up to real
time.)
3.2.5.4 FIFO (First In First Out)
Syntax: FIFO
Instructs the CD24 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 CD24 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.
44 Issue C