Specifications

M1 Control RS-232 ASCII String Protocol Page 11 of 68 Rev. 1.79 July 16, 2009
1. General
This document describes the protocol specifications for the ELK M1 Security and
Automation Controller’s RS232 serial interface port and related controls including the ELK
EZ8 Control. This port allows communications between the M1 and various ‘third party’
devices such as computers, lighting, HVAC, and many types of automation devices on a real-
time basis.
Connection to the port is via a 9-pin “DB-9” cord. You can use any PC connected to the
RS232 port to communicate with the control panel. You can use any software capable of
sending ASCII strings through your PC’s COM ports.
2. Electrical/Mechanical Specifications
The interface connector supports a limited RS-232 hardware interface configured as DCE
(Data Communication Equipment). The pin-outs are GND – Pin 5, and the TXD – Pin 2, RXD
– Pin 3 signals. The control panel ignores all handshake lines when sending data, so connected
equipment must be capable of receiving continuous 9600 to 115,200 baud data.
To connect to a computer use as straight through serial cable. To connect to other DCE
configured serial ports, a null modem and maybe a gender changer will be required.
Communication settings should be 9600 to 115,200 baud, 8 data bits, no parity, and one
stop bit. Logic levels at the interface are standard RS-232. The interface is full duplex. Baud
rates must be set in the M1 Global programming section.
3. Error Checking
The transmission contains checksum and packet length error checking. No acknowledge or
re-transmission capability is implemented.