Guralp Systems CMG-CD24 User Manual

Page 76

CMG-CD24

You can retrieve blocks from a digitiser in FILING mode by connecting

to its terminal interface and issuing DOWNLOAD commands, or by
transferring the data to a FireWire disk.

When in FILING mode, a digitiser transmits “heartbeat” messages over

its data port. These short messages take the place of blocks, and
ensure that programs such as Scream! know that a digitiser is present.

You can change the frequency of heartbeat messages using the
command HEARTBEAT.

5.9.3 DUPLICATE

Syntax: DUPLICATE

Instructs the CD24 to transmit all new data directly to clients (as in
DIRECT mode) as well as storing it in Flash memory (as in FILING

mode). If a client fails to acknowledge a block, the digitiser does not
attempt to retransmit it.

5.9.4 DUAL

Syntax: DUAL

Instructs the CD24 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 this mode, the digitiser will send heartbeat messages in
addition to any continuous streams you have configured. Scream! can

pick these up and download new data as necessary.

5.9.5 ADAPTIVE

Syntax: ADAPTIVE

Instructs the CD24 to transmit current blocks to clients if possible, but

to store all unacknowledged blocks in the Flash memory and re-send
them, oldest first, when time allows.

5.9.6 FIFO

Syntax: FIFO

Instructs the CD24 to begin writing blocks to Flash memory as for
FILING, 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.

Issue C