LASSEN SERIES 16 & 32 HD/SDI
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When a “G” command is sent by the router, it will always include this space, but the space is
optional when sending a “G” command to the router.
Character string
arguments are delimited on both sides by a
tilde
(‘~’) character. Generally
character strings may contain any printable ASCII character except
tilde, asterisk,
and
exclamation.
Every “G” command must be terminated with a
tilde
(‘~’) character. This allows a command
parser to ignore any received “G” command that has a command_name that it doesn’t know
about.
The “G” commands available for any given router may vary, depending on the router model. The
“G SUPPORTED” command allows controllers to find out whether particular “G” commands are
supported by a given router or not.
A router may be sent “G” commands that it doesn’t understand. It will simply ignore them and
generate an ERROR response.
VAR: Modify or query system variables
Action From
Syntax
Modify
Host
G
VAR,<varname>,<value>[,<value>…]~
Query
Host
G
VAR,<varname>~
Query Response
Router (same as Modify)
Modify is Protected:
Yes
Report Changes:
No
The “G VAR“ command is used to change or query system variables that control specific features
of the router. The variable being affected is specified using its name, and only one variable at a
time can be targeted by this command. The features being controlled are typically system
options that allow the user to control special hardware or software enhancements to the router
code.
The
Modify
command has two or more arguments, the name of the variable to be changed and
the new value of that variable. Most variables have only a single value associated with them, but
it is possible for a variable to be multi-valued, in which case the number of <value> arguments
may be two or more.
The
Query
command has the variable name whose value is to be queried as the only argument.
The
Query Response
command has the same argument structure as the
Modify
command.
Each different router may support different variables. The supported variables may grow over
time, as enhancements are added to this protocol, so command parsers should generally ignore
unknown variable names. The routers themselves will ignore any command that is received with
an unknown variable name or an invalid variable value. Use the “G VARQRY” command to find
out which variables a particular router actually supports. Refer to documentation for each router
for a description of the variables.
A variable value is typically an unsigned decimal number, but may also be a signed decimal
number. The “G VARQRY” command can be used to determine the allowed range of values.
For example, to query for the value of a variable named “VI_DELAY”:
** G VAR,VI_DELAY~ !!
The response command might be:
** G VAR,VI_DELAY,4~ !!
To set the “HD_SLAVE” variable to 1:
** G VAR,HD_SLAVE,1~ !!
