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Table 4 modbus™ special registers – Detcon IR-700 User Manual

Page 32

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Model IR-700

IR-700 Instruction Manual

Rev. 3.1

Page 28 of 40

FC

REG

Content Description

R/W

Content Definition

Value

Meaning

Range

03/

06

40012

Special #2

R/W

Function dependent on value of

40006 (See Special Register

Table 4)

03

40013

Special #3

R

Function dependent on value of

40006 (See Special Register

Table 4)

03/

06

40014

Special #4

R/W

Function defendant on value of

40006 (See Special Register

Table 4)

03

06

40015

40015

Calibration Status

Calibration Enable

R

W

0x0000
0x0001
0x0002
0x0003
0x0004
0x0001
0x0002
0x0008
0x0009
0x000A
0x000B

Idle
Zero Calibration Started
Span Calibration Started
Span Set
Span Calibration Unsuccessful
Set Zero
Set Span
Signal simulation mode
Set FP Bridge Voltage
Set TP Heater Power
Set IR Gain

03

40016

Read Text 1, first char in

L

R

Two Char of Gas/Units String

6

03

40017

Read Text 2

R

Two Char of Gas/Units String

6

03

40018

Read Text 3

R

Two Char of Gas/Units String

6

03

40019

Read Text 4

R

Two Char of Gas/Units String

6

03

40020

Read Text 5, last char in

H

R

Two Char of Gas/Units String

6

03

40021

Text null terminator in L

R

Two Char of Gas/Units String

6

1

Integer ranges from 1 all the way to 10,000.

2

Units are determined by “units” field in the “notation” string

3

Gas Reading times one (x 1) with units in notation string for “Low Range” = 0. Gas Reading times one (x 10) with units in notation string for “Low

Range” = 1. Gas Reading times one (x 100) with units in notation string for “Low Range” = 2.

4

Span Gas must be less than or equal to Detectable Range and is usually about ½ of it.

5

Fault status bits self-reset when fault clears

6

Text in ASCII, in order L byte, H byte, L byte… See field descriptions of notation string.

Gas/Units String

Character #

1

2

3

4

5

6

7

8

9

10

11

Description

Units

0x20

Gas Type

0x00

Units – This field is ‘PPM’, ‘PPB’, or ‘_ _ %’ (where ‘ _ ‘ is a space, 0x20).
0x20 – The units filed is terminated with an ASCII space (0x20)

Gas Type – This field contains the gas type of the cell. Any ASCII string is permissible
0x00 – The notation string is terminated with an ASCII null character

Table 4 Modbus™ Special Registers

REG

DM (40006 = 1)

FP (40006 = 2)

IR (40006 = 3)

TP (40006 = 4)

1

PI (40006 = 5)

40011

Low Range= 0, 1, 2
0: Range >25 (0 decimal place)
1: Range 10-25 (1 decimal place)
2: Range <10 (2 decimal place)

Gas Factor (R/W)
Range = 79 to 565

Gas Factor (R/W)
Range = 20 to 565

Heater Power
(mW) (R/W)

Low Range= 0, 1, 2
0: Range >25
1: Range 10-25
2: Range <10

40012

0x8XXX
0x0XXX
0xX000
0xX096
0xX0C8
0xX12C

Positive Polarity Cell
Negative Polarity Cell
Bias = 0mV
Bias = 150mV
Bias = 200mV
Bias = 300mV

Cal Factor (R/W)
Range = 79 to 565

Active Counts

Heater Voltage
(mV)

0x8XXX
0x0XXX
0xX000
0xX096
0xX0C8
0xX12C

Positive

Polarity

Cell
Negative

Polarity

Cell
Bias = 0mV
Bias = 150mV
Bias = 200mV
Bias = 300mV

40013

Gain Code
(integer between 0 & 15)

Bridge Current (mA)

Reference Counts

Sensor Resistance
(x100 Ω)

Gain Code

40014

Raw Counts 0-0xFFFF
(0x8000 = nominal 0)

Bridge Voltage (mV)
(Read only)

Range Divisor
1,10,100, or 1000

Heater Current
(mA )

Raw Counts

1

Only possible ranges are 20, 50, 100, 200. Modbus register 40001 will contain either 20, 50, 100, or 200, range divisor is not necessary.