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Start character, Device address, Command/response – Comtech EF Data CIM-300L User Manual

Page 93: 1 start character, 2 device address 5.3.3 command/response

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CiM-300L IP Enabled Satellite Modem

Rev. 1

Serial Remote Control

CD/CIM300L.IOM

67

5.3.1 S

TART

C

HARACTER

A single character precedes all messages transmitted on the remote link. This character
flags the start of a message. This character is:

!

“<” for commands

!

“>” for responses

5.3.2 D

EVICE

A

DDRESS

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 1 to 255.

Note: 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 software selectable at the modem, and
must be in the range of 1 to 255.

5.3.3 C

OMMAND

/R

ESPONSE

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 cannot be implemented, a negative acknowledgment message is
sent in response. This message is:

>add/?ER1_parity error'cr''lf']

(Error message for received parity errors.)


>add/?ER2_invalid parameter'cr''lf']

(Error message for a recognized command which cannot 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.)