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Detcon 1000_CO2 User Manual

Page 24

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Model 1000 CO2

Model 1000 CO2 Instruction Manual

Rev. 2.2

Page 20 of 28

However, any change to the RS-485 ID number would require the sensor housing to be opened, thus
declassification of the area would be required. See section 3.4 for details on changing the RS-485 ID number.

The following section explains the details of the Modbus™ protocol that the Detcon MicroSafe™ sensor
supports.

Code 03 - Read Holding Registers is the only code supported by the transmitter. Each transmitter contains 6
holding registers which reflect its current status.

Register #

High Byte

Low Byte

40000

Gas type

Sensor Life


Gas type is one of the following:
01=CO, 02= H

2

S, 03=SO

2

, 04=H

2

, 05=HCN, 06=CL

2

, 07=NO

2

, 08=NO, 09=HCL, 10=NH

3

, 11=LEL, 12=O

2


Sensor life is an estimated remaining use of the sensor head, between 0% and 100%
Example: 85=85% sensor life

Register #

High Byte

Low Byte

40001

Detectable

Range


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

Register #

High Byte

Low Byte

40002

Current Gas Reading


The current gas reading is a whole number. If the reading is displayed as 23.5 on the display, this register
would contain the number 235.

Register #

High Byte

Low Byte

40003

Alarm 1 Set point


This is the trip point for the first alarm.

Register #

High Byte

Low Byte

40004

Alarm 2 Set point


This is the trip point for the second alarm.

Register #

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