Sierra Video RTR-804 - Manual (Page 18)

SIERRA VIDEO
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string followed by a string of trailer characters and a CR character, to the host. An error
can be caused by an unknown command name or bad arguments to a command.
The simplest possible command string would be:
**!!
which consists of the leader and trailer characters but no commands between them. This
command string would generate the response:
** OK !!
This can be useful for verifying that the serial link to the router is operational. In Routing
Switchers requiring only one leader/trailer character, the simplest command string would
be:
*!
which would generate the response:
* OK !
(To determine whether a particular router uses one or two leader/trailer characters, send
it "!!**" and check the response to see which of the above two responses it is. It won't hurt
to always use two even if only one is required.)
The simplest error response is one with no optional descriptive string. For example, this
command string:
** XXX !!
might generate this response from the router:
** ERROR !!
Beginning with version 5.01 of the Tahoe/Sierra/Yosemite router software, a descriptive
text string was added following the word "ERROR", to help with diagnosing the error. For
example, the above command string might generate this response from a router running
this newer software:
** ERROR Syntax:No Number:XX !!
The descriptive string always ends with a colon and up to three characters from the
command string that caused the error. Generally, the error can be assumed to have
occurred just before these characters.