Mitsubishi Electronics WD8700U manual Control command configuration, Control sequence, Ack/Nak

2. Control command configuration

The command consists of the address code, ID code, function code, data code, ACK/NAK, and end code. The length of the command varies among the functions.

	Address code		ID code	Function code	Data code	ACK/NAK	End code
ASCII code		‘30h’ ‘30h’	‘3Bh’ ID ‘3Bh’	Function	Data	‘3Ah’ ‘4Eh’	‘0Dh’
Character		00	;ID;	Function	Data	:N
[Address code]		Fixed to 00. (‘30h’ ‘30h’ in the ASCII code)
[ID code]		Code specifying the projector to be controlled (For ID, specify either the PROJETOR ID (00 to
		63) or GROUP ID (0A to 0Z). When the code is not specified, all the connected projectors are
		controlled.)
[Function code]		Code unique to each control operation.
[Data code]		Data (value) unique to each control operation (Not always indicated.)
[ACK/NAK]		Code indicating the NAK return as described below
		Fixed to :N (‘3Ah’ ‘4Eh’ in the ASCII code. Not added to ACK.)
[End code]		Fixed to	. (‘0Dh’ in the ASCII cade)

3. Control sequence

[Example]		When the personal computer and two projectors are daisy-chained:
Computer		Projector 2		Sequence	Note
	Projector 1
			1	Send the command from the
	1			personal computer to the projector.
	3	2		The command input from the
			2	SERIAL IN terminal is sent to the
		3
				projector connected to the SERIAL
	4			OUT terminal.
				After receiving the end code, the	If the projector does not receive commands
	5			projector sends the return command	normally, that is, if the projector is not connected
				to the device connected to the	physically or unable to receive commands, it does
		5
	6			SERIAL IN terminal.	not send out a return command.
		6			In addition, when the ID code of the command is not
			3		corresponded to that of the projector, the projector
	6				doesn’t send a return command.
					The projector sends out a return command within
					one second at the latest.
					When the received command cannot be executed,
					NAK is returned (as described below).
				The return command input from the	The personal computer receives the commands as
				SERIAL OUT terminal is sent to the	many as the number of the projectors that send the
			4	device connected to the SERIAL IN	returned commands. However, the receiving order
				terminal.	of the returned commands may vary depending
					on the projector status.
				The personal computer checks the
			5	command and confirms if the sent
				command has been received or not.
				Use the check command to see	This projector sends various codes other than the
			6	if the projector has executed the	return code. When having a control sequence by
				command.	RS-232C, reject other codes from the personal
					computer.

•NAK return

In the following cases, the projector returns the command with “:N” added.

(1)Though the command sent from the computer is received by the projector successfully, it cannot be executed because the projector is in the operation prohibition state.

(2)The data length of the sent command is incorrect or the command is invalid.

(3)The ID assigned to the command is out of the valid range (other than 00 to 63 or 0A to 0Z).

(4)The signal length of the command is 48 bytes or longer.

•When a command is sent out during the following operations, it may not be executed.

(1)During signal switching

(2)In the process of the auto position

(3)After the power is turned on.

After the power is turned on, no command is received until the image is displayed. (Usually, it takes about 20 seconds. However, when the lamp illumination takes time, more time will be required accordingly.) In this case, the projector returns the received command with NAK added.

•The return command is sent out within 1 second at the latest.

•When sending commands successively, wait to receive the return command of the current command before sending a next command.

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