Xantech mrc88 Appendix, RS232 CONTROL, Types Of Commands, INTERFACING TO THE RS232 COMPORT, Pin #

Page: 86 Model MRC88

Section 9: Appendix

RS232 CONTROL

This document describes the bi-directional RS232 interface of the MRC88 using the COM PORT on the rear of the system (Fig. 3-29). This interface allows an external RS232 device to control the MRC88 via a set of ASCII text commands. It is also possible to control any IR device connected to the MRC88 system as well by triggering individual IR Commands and/or IR Macros via ASCII strings.

In EXPANDED Mode, the Primary and Secondary units RS232 ports are both active although only the Primary’s RS232 port will be bi-directional. The Secondary units RS232 port can only be used as a Control

INPUT.

EXAMPLE: Interface the Primary’s RS232 port to a Lighting/HVAC/Security system allowing the MRC88 system to control the other system or be controlled by it (bi-directional control). The Secondary units RS232 port can be connected to a touch screen controller for a Master Controller for the entire system including control of the Lighting/HVAC/Security system connected to the Primary units RS232 port.

TYPES OF COMMANDS

There are two types of information that can be sent to the MRC88 Controller: COMMANDS and QUERIES. COMMANDS are ASCII strings used to set a specific parameter in the system (i.e. Select a Source, turn a zone ON, start a DVD player etc…). QUERIES are requests for system status information and result in the MRC88 controller sending back a reply to the string being sent (i.e. seeing what zones are on, which sources are selected and volume settings etc….)

INTERFACING TO THE RS232 COMPORT

The RS232 Com Port on the rear of the MRC88 Controller, is wired as a ‘null modem’ end, meaning the Transmit and Receive line have already been interchanged for direct communication with a PC. What this means is when connecting to a standard PC’s Com Port, no Null Modem cable is necessary.

The pin out configuration for this connector is:

	COM PORT
PIN #	FUNCTION
1, 8, & 9	NC
2	Tx
3	Rx
4	DTR
5	GND
6	DSR
7	RTS

Table 2: Rear Com Port Connector Pin Out

ASCII STRING ‘INITIATING’ AND ‘TERMINATING’ CHARACTERS

The protocol was designed to be similar to the one used in the Xantech ZPR68 so that it would be familiar. It is different from the ZPR68 in that the MRC88 has a buffered UART and is therefore able to receive a complete command/query string at one time.

© 2003 Xantech Corporation