NEC RS-232C user manual Communication Format, Header block format fixed length

4. Communication Format

Header

Message

Check Code

Delimiter

The command packet consists of four parts, Header, Message, Check code and Delimiter.

Sequence of a typical procedure to control a monitor is as follows,

[A controller and a monitor, two-way communication composition figure]

Controller

Get Parameter

Delimiter Check Code Message Header

Get Parameter Reply

Header Message Check Code

Set Parameter

Delimiter Check Code Message Header

Set Parameter Reply

Header Message Check Code

Monitor

	The controller sends command to
	get a value from the monitor that
	you want to change.
Delimiter	The monitor replies a current value
	of the requested item.
	The controller sends commands to
	set an adjusted value.
Delimiter	The monitor replies to the
	controller for confirmation.

Get Parameter

Delimiter Check Code Message Header

Get Parameter Reply

Header Message Check Code Delimiter

Save Current Setting Command

Delimiter Check Code Message Header

The controller sends command to get a value for confirmation.

The monitor replies an adjusted value.

The controller requests to store the adjusted value to the monitor.

Save Current Setting Command Reply

Header	Message	Check Code	Delimiter	The monitor replies to the
				controller for confirmation.

Command

Delimiter Check Code Message Header

Command Reply

Header Message Check Code

The control does not suitable for above fixed protocol; use the proper command for each control. Please refer section 5.5 and section 7 to 13.

Delimiter The monitor replies a proper message defined for each control.

4.1 Header block format (fixed length)

Header

Message

Check code

Delimiter

SOH	Reserved	Destination	Source	Message	Message
	'0'			Type	Length
1st	2nd	3rd	4th	5th	6th -7th

1stbyte) SOH: Start of Header

ASCII SOH (01h)

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