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6.5 Register Address Map
This section describes the register address map for the data used by this detector.
The detector assigns its data (e.g. gas concentrations, status information, device setup details) to its holding
registers. A request message from the master specifies the register addresses to read from/write to.
Modbus Register Address Map
Register
address
Relative
address
(hex)
Register name
Read (R) or
Write (W)
Data
type
Data contents
40001
0
Flow rate
R
Word
Read current flow rate
Response example: 0x01F4 when flow
rate is measured at 500ml
40002
1
AL1 set value
R
Word
Read AL1 set value
Response example: 0x0019 when AL1
set value is 25%F.S.
40003
2
AL2 set value
R
Word
Read AL2 set value
Response example: 0x0028 when AL2
set value is 40%F.S.
40004
3
Alarm mode
combination
R
Word
Read alarm mode combination
0: High-High limit 0x0000
1: Low-Low limit 0x0001
2: High-Low limit 0x0002
40005
4
AL1 delay time
R
Word
Read AL1 delay time
Response example: 0x0005 when delay
time is 5 sec
40006
5
AL2 delay time
R
Word
Read AL2 delay time
Response example: 0x0005 when delay
time is 5 sec
40007
6
Zero suppression
value (21vol%
suppression value
for oxygen)
R
Word
Read zero suppression value
Response example: 0x0019 when
suppression value is 25%
40009
8
Target gas (1st
and 2nd letters)
R
Word
Read target gas
Target gas (max. 4 letters) are set in hex
ASCII code.
Response example: When target gas is
CO
2
, 1st letter “C”, 2nd letter “O” and 3
rd
letter “2” are returned in hex ASCII code
“C”: 0x43 (high-order byte of word data)
“O”: 0x4F (low-order byte of word data)
“2”= 0x32 (high-order byte of word data)
“(space)” = 0x20 (low-order byte of word
data)
When gas name exceeds 5 letters, first
4 letters will be returned.
40010
9
Target gas (3rd
and 4th letters)
R
Word
40011
A
Measurement unit
code
R
Word
Read unit code for sensor unit
0: (None),
1: ppm,
2: ppb,
3: %
