Instruction Manual

The following section explains the details of the Modbus™ protocol that the IR-622 MicroSafe™ sensor supports.

Code 03 - Read Holding Registers, is the only code supported by the transmitter. Each transmitter contains 6 hold-

ing registers which reflect its current status.

High Byte Low Byte

40000 Gas type Sensor Life

Gas type is one of the following:

01=CO, 02=H2S, 03=SO2, 04=H2, 05=HCN, 06=CL2, 07=NO2, 08=NO, 09=HCL, 10=NH3, 11=LEL, 12=O2

Sensor life is an estimated remaining use of the sensor head, between 0% and 100%

Example: 85=85% sensor life

40001 Detectable Range

i.e. 100 for 0-100 ppm, 50 for 0-50% LEL, etc.

High Byte Low Byte

40002 Current Gas Reading

The current gas reading as a whole number. If the reading is displayed as 23.5 on the display, this register would

contain the number 235.

High Byte Low Byte

40003 Alarm 1 Setpoint

This is the trip point for the first alarm.

40004 Alarm 2 Setpoint

This is the trip point for the second alarm.

High Byte Low Byte

40005 Status Bits Status Bits

High Byte

Bit 7 Not used, always 0

Bit 6 Not used, always 0

Bit 5 Not used, always 0

Bit 4 Not used, always 0

Bit 3 1-Unit is in calibration 0-Normal operation

Bit 2 1-Alarm 2 is ascending 0-Alarm 2 is descending

Bit 1 1-Alarm 2 is normally energized 0-Alarm 2 is normally de-energized

Bit 0 1-Alarm 2 is latching 0-Alarm 2 is non-latching

Low Byte

Bit 7 1-Alarm 2 Relay is energized 0-Alarm 2 Relay is not energized

Bit 6 1-Alarm 1 is ascending 0-Alarm 1 is descending

Bit 5 1-Alarm 1 is normally energized 0-Alarm 1 is normally de-energized

Detcon Model IR-622 Combustible Hydrocarbon Sensor PG.19