Carbon Monoxide Transmitter Modbus
Installation Manual
May 5, 2017
IN-CMD5B4MOD-01-01 Page 13
ASCII Mode Message Format
Modbus Framing
ASCII characters 0…9, A…F
Data Bits
start bits --- 1
data bits --- 7
parity bits --- none, odd or even
stop bits --- 1or 2
Baud Rate
300, 600, 1200, 2400, 4800, 9600 or 19200
Duplex Half
duplex
Error Checking
Longitudinal Redundancy Check (LRC)
Latency
More than 3.5 characters --- minimum, 50, 100, 150, 200, 250, 300 or 350 mS
Framing Support and Bit Sequences
RTU
Mode
Start 1 2 3 4 5 6 7 8 Stop
Start 1 2 3 4 5 6 7 8 Stop Stop
Start 1 2 3 4 5 6 7 8 Odd Stop
Start 1 2 3 4 5 6 7 8 Even Stop
ASCII
Mode
Start 1 2 3 4 5 6 7 Stop Stop
Start 1 2 3 4 5 6 7 Odd Stop
Start 1 2 3 4 5 6 7 Odd Stop Stop
Start 1 2 3 4 5 6 7 Even Stop
Start 1 2 3 4 5 6 7 Even Stop Stop
Modbus Register Addressing
Modbus
Address
Typical
Offset
Units
Data
Type
Access Notes
40001 +0 Word
Read
Unsigned 16-bit integer
0x0000 = CO in normal status, 0x0001 = in abnormal status
40002
+1
PPM
Word
Read
Unsigned 16-bit integer, CO value
40003 +2
°F/°C
Word
Read
Unsigned 16-bit integer, Temperature value x 10
(the application program must divide the value by 10)
(For example: 214 = 21.4 °C) (0-50 °C / 32-122 °F range)
40004 +3
Word Read
Unsigned 16-bit integer
0x0000 = buzzer not activated, 0x0001 = buzzer activated
40005 +4
Word Read
Unsigned 16-bit integer
0x0000 = relay1 not activated, 0x0001 = relay1 activated
40006 +5
Word Read
Unsigned 16-bit integer
0x0000 = relay2 not activated, 0x0001 = relay2 activated
40007 +6
Word Read
Unsigned 16-bit integer
0x0000 = test not activated, 0x0001 = test activated
40008 +7
Word Read
Unsigned 16-bit integer
0x0000 = fault not activated, 0x0001 = fault activated