Omron CQM1H-SCB41 operation manual Appendix N, Hayes Modem AT Command Protocol

Appendix N

Hayes Modem AT Command Protocol

The Hayes Modem AT Command Protocol is used to make various settings or control remotely a Hayes modem connected to the Serial Communications Board via RS-232C cable.

Protocol Configuration

The configuration of the Hayes Modem AT Command Protocol is shown below.

Sequence	Communications	Function	Ladder interface
No.	sequence name
			Send word	Receive word
			allocation	allocation
550	Initialize modem	Initializes the modem connected to the	Yes	No
	(general-purpose)	Serial Communications Board. The
		initialization command is set in the words
		specified for the second operand of
		PMCR.
560	Initialize modem	Initializes certain OMRON Modems.	No	No
570	(specialized)
580
561	Dial	Dials from the modem connected to the	Yes	No
571		Serial Communications Board. AT
581		commands and telephone numbers are set
		set in the words specified for the second
		operand of PMCR. This sequence can be
		used only for certain OMRON modems.
552	Password	After the line is connected, the password	Yes	No
		sent from the other exchange is verified to
		confirm that the line is connected to the
		desired exchange. The normal value of a
		password is set in the words specified for
		the second operand of PMCR.
553	Data send/receive	Sends arbitrary data to the exchange	Yes	Yes
	(general purpose	which the line is connected. Send data is
	sequence)	set in the words specified for the second
		operand of PMCR. Receive data is stored
		in the words specified for the third operand
		of PMCR.
554	Escape	Shifts the modem to escape mode (the	No	No
		condition in which command input is
		available during data communications).
		The escape code is fixed to “+++”
555	Hang up	After shifting to escape mode, the line is	No	No
		disconnected.
562	Initialize and dial	Executes continuously from initialization to	Yes*	No
572		dialling operations for certain OMRON
582		Modems.
590	Escape to hang up	Executes continuously from shifting to the	No	No
		escape mode to hanging up.

Note 1.	Ladder Interface Settings
	YES:	User settings are required for the 2nd and 3rd operands of PMCR.
	NO:	Send word allocation:	Set a dummy word address for the 3rd operand (D).
		Receive word allocation:	Set the constant 0000 for the 2rd operand (S).
2.	For details about dialling, refer to sequences 561, 571 and 581.

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