Carbon Monoxide Transmitter Modbus
Installation Manual
May 5, 2017
IN-CMD5B4MOD-01-01 Page 16
0x03 --- Read CO PPM
Query
Slave address
(0x01 to 0xFF)
0x03 0x00 0x01 0x00 0x01
CRC
LSB
CRC
MSB
Response
Slave address
(0x01 to 0xFF)
0x03 0x02
Register value
MSB (PPM)
Register value
LSB (PPM)
CRC
LSB
CRC
MSB
* Register value = 0x0000 to 0x01F4, corresponding to 0 to 500 ppm
0x03 --- Read Temperature
Query
Slave address
(0x01 to 0xFF)
0x03 0x00 0x02 0x00 0x01
CRC
LSB
CRC
MSB
Response
Slave address
(0x01 to 0xFF)
0x03 0x02
Register value
0x00
Register value
(C/F x 10)
CRC
LSB
CRC
MSB
Note: The temperature reading will only be valid for space type products (sensor on front cover) when the product is
mounted flat on a wall with the sensor facing the operator and the LCD to the top. Changing the position will create
reading inaccuracies.
The temperature register will not give accurate duct temperature values for duct style products (air flow pickup tube
on the rear of the enclosure).
0x03 --- Read Buzzer Status
Query
Slave address
(0x01 to 0xFF)
0x03 0x00 0x03 0x00 0x01
CRC
LSB
CRC
MSB
Response
Slave address
(0x01 to 0xFF)
0x03 0x02
Register value
0x00
Register value
LSB
CRC
LSB
CRC
MSB
* Register value = 0x0000 = buzzer not activated, 0x0001 = buzzer activated
0x03 --- Read Relay 1 Status
Query
Slave address
(0x01 to 0xFF)
0x03 0x00 0x04 0x00 0x01
CRC
LSB
CRC
MSB
Response
Slave address
(0x01 to 0xFF)
0x03 0x02
Register value
0x00
Register value
LSB
CRC
LSB
CRC
MSB
* Register value = 0x0000 = relay 1 not activated, 0x0001 = relay 1 activated