P/N 3100345 ISSUE 2
PAGE 4
1.3
RS485 COMM supports 1200, 2400, 9600 and 19200 baud rate using 8 data bits and one stop bit. Parity is not
supported. Refer to Table 1.3 for Baud Rate switch configuration. Set S1 positions 6-7 for the desired Baud
Rate configuration.
Table 1.3 Network Baud Rate setting
Baud Rate
S1-6
S1-7
1200
OPEN
OPEN
2400
CLOSED
OPEN
9600
OPEN
CLOSED
19200
CLOSED
CLOSED
1.4
Set 100-ohm termination resistor (if required). Network termination is required if the unit is located at the
beginning or end of the network bus. Termination reduces unwanted reflections caused by data signal
propagation due to long wire runs. Refer to Table 1.4 for switch configuration. Set S1 position 8 for network
termination if required.
Table 1.4 Termination setting
Termination (100 ohms)
S1-8
Enabled
CLOSED
Disabled
OPEN
2.0
Messaging Format
2.1
The RS485 COMM utilizes the Edwards SigNet ASCII protocol for data messaging. Each unit is capable of
consuming and/or producing messages from the master controller. SigNet message format is illustrated
below.
<STX> <UA> <DDDD> <ZONE> <ETX> <CHKSUM>
<STX>
The <STX> character has a value of 2 hexadecimal and is required at the start of
every message (1 byte).
<UA>
Two byte ASCII representation of the hex Unit. Example - If unit address 0A is
chosen, the two byte <UA> data field would contain ASCII ‘0’ and ‘A’ written in
ASCII format as 0A. Valid data range is ASCII 00 - 1F.
<DDDD>
ASCII data field. (4 bytes total). These bytes contain commands, tone/message
and timed sequence data.
<ZONE>
Programmable unit Zone issued by the master or controlling computer
Range ASCII A-D (1 byte). Note – Zone value is not retained after power loss unless
battery backup is installed. Value defaults to Zone A on power up.
<ETX>
The <ETX> character has a value of 3 hexadecimal and is required at the end of
every message (1 byte)
<CHKSUM>
Optional two byte Message Block checksum (2 bytes). Refer to Section 4.0 for
Block checksum calculation and verification. If checksum is not desired, must pad
these two bytes with two ASCII zeros 00.
3.0
Message Command Set
3.1
Tone/Message Command - 00-1F
Send Format: <STX><UA><TONE> <TIME> <ZONE> <ETX> <CHKSUM>
<UA>
Unit address characters (2 bytes). See Section 2.0, Messaging Format
<TONE>
Tone/Message to be played by the unit. Example - If tone 06 is chosen, the two
byte <TONE> data field should contain ASCII ‘0’ and ‘6’ written in ASCII format as
06. Range ASCII 00-1F(2 bytes). See Tone Chart for a list of available tones or
messages.
<TIME>
Time sequence for Tone/Message to be played (00-99 seconds). For continous play
of Tone/Message, use ‘00’ in this data field. Range ASCII 00-99 (2 bytes)
<ZONE>
Units matching this zone field will play Tone/Message indicated in the <TONE>
data field for specified time indicated in <TIME> data field. All other zones remain
in standby mode.
