Comtech EF Data SDM-309B - Manual (Page 179)

Remote Control SDM-309B Satellite Modem
B-B–2 MN/U-SDM309B Rev. #
3.1 Start Character
A single character precedes all messages transmit on the remote link.
This character flags the start of a messege. This character is:
! “<“ for commands and
! “>“ for responses.
3.2 Device Address
The device address is the address of the one satellite modem which is designated to
receive a transmitted command, or which is responding to a command. Valid device
addresses are 1 to 3 characters long and in the range of 0 to 255. Address 0 is reserved as
a global address which simultaneously addresses all devices on a given communications
link. Devices do not acknowledge global commands.
Each satellite modem which is connected to a common remote communications link must
be assigned its own unique address. Addresses are hardware (dipswitch) selectable at the
modem and must be in the range of 1 to 255.
Note: “add” is used to indicate a valid 1 to 3 character device address in the range
between 0 and 255.
3.3 Command/Responses
The command/response portion of the message contains a variable length character
sequence which conveys command and response data.
If a satellite modem receives a message addressed to it which does not match the
established protocol or can not be implemented a negetive acknowledgement message is
sent in response. This message is:
>add/?ER1_PARITY ERROR”cr””lf”]
(error message for parity errors)
>add/?ER2_INVALID PARAMETER”cr””lf”]
(error message for a recognized command which can not be implemented or has parameters which are
out of range)
>add/?ER3_UNRECOGNIZABLE COMMAND”cr””lf”]
(error message for unrecognizable command or bad command syntax)
>add/?ER4_MODEM IN LOCAL MODE”cr””lf”]
(MODEM in local error, use the REM command to go to remote mode)
>add/?ER5_HARD CODED PARAMETER”cr””lf”]
(error message indicating that the parameter is hardware dependent and may not be changed remotely)
3.4 End Character