Sea Air and land Communications Ltd, 10 Vanadium lace, Addington, Christchurch 8024, New Zealand April 2017
Operation
Each input module will send it’s input message when triggered, to the downstream unit
(connected to the left hand side RJ12 socket). This may be either a transmitter, or another input
module. A module connected downstream will acknowledge receipt of a Salcom protocol
message, so reliable delivery to the transmitter can be ensured.
The input module may be configured to operate without acknowledging, so that input
modules may be connected to a C or unit that does not support Salcom protocol (but this is
not advised, since messages may be lost).
When configured to wait for acknowledgment the input module will attempt to resend the last
message again with a frequency as set by the user (up to every 10 seconds – default 1
second).
When a message cannot be acknowledged (probably due to a break in a serial cable link
somewhere downstream) the input module may eventually fill its message queue, and stop
acknowledging messages from upstream modules. If the input module is in an error or busy
state preventing the offloading of messages, the module “breaking” the chain can easily be
identified by inspecting the serial traffic and error LEDs.
