Appendix C Modbus Holding Register Map - Michell Instruments QMA401 User Manual

APPENDIX C
Appendix C Modbus Holding Register Map
All the data values relating to the QMA601 are stored in holding registers. Each of these registers
is two bytes (16-bits wide). Some of these registers contain instrument specific values e.g. its own
unique system address, IP address values, etc. Others registers hold specific real time data such as
temperature.
Each Modbus message has a two part address code, one for the low byte (bits 0 through 7) and one
for the high byte (bits 8 through 15). The facility exists for multiple registers, specified by a high and
low byte contained in the query message, to be addressed and read by the same message.
The table below describes the instruments' registers with their respective address locations, together
with their relevant register configurations and register map definitions.
The register maps below the table define the data allocated to each bit/byte for each register type.
Address Function Description
#
0 ModBus Configuration
1 System Configuration
2 Alarm Configuration
3 Analogue Output Configuration
4 Internal Logging Configuration
MFC Span in mlm / Gas Number for flow
5
rate and mol weight correction
6 PID – Proportional Value
7 PID – Integral Value
8 PID – Derivative Value
Warning Relay Alarm warning selection
9
Dryer Capacity (ppm) / Moist Gen Capacity
10
11 Signal Filter Settings
12 Alarm1 – Low Set point
13 Alarm1 – High Set point
14 Alarm2 – Low Set point
15 Alarm2 – High Set point
16 Alarm3 – Low Set point
17 Alarm3 – High Set point
18 Analogue Out 1 – Low Set point
19 Analogue Out 1 – High Set point
20 Analogue Out 2 – Low Set point
21 Analogue Out 2 – High Set point
22 Fixed Pressure Input Value
23 Next Calibration – Configuration
24 User low ppmV limit
25 Next Calibration – Intervals between cal
Next Calibration – External Cal Val – Hi
26
Next Calibration – External Cal Val – Lo
27
28 Last Cal Day/Month/Year
29 Last Cal Details
30 Last Cal - 1 Day/Month/Year
66
Read/
Write
mask
(days)
Word
Word
QMA401 User's Manual
Default Register
Config
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W 255 / 103
R/W
R/W See App A
R/W See App A
R/W See App A
R/W See App A
R/W See App A
R/W See App A
R/W See App A
R/W See App A
R/W See App A
R/W See App A
R/W See App A
R/W
R/W
R/W
R/W
R/W
R
R/W
R
97450 Issue 2, March 2018
Notes/ Real Value
Range
C
D
E
F
U
S
A3 0.01-100.00%
A3 0.01-1000.0%
A3 0.01-100.00%
M
V
W
P1
A3 0.00 to 0.10
P2
I 0.01 to 2000.00 ppmv
I 0.01 to 2000 .00ppmv
J
SCF can be set (for
K
factory calibration)
J