Alstom iSTAT M232 - Appendix A: Modbus Protocol; Modbus Communication Protocol; Register Map for Actual Measurements

M2x2/EN M/F User Manual
iSTAT M2x2 Page 55
17. APPENDIX A: MODBUS PROTOCOL
17.1 Modbus communication protocol
Modb
us protocol is enabled via the RS232 or RS485 communication port on the M232.
Modbus protocol enables operation of the device on Modbus networks. For the M232 the
Modbus protocol enables point to point (for example Device to PC) communication via
RS232 communication and multi drop communication via RS485 communication.
The memory reference for input and holding registers is 30000 and 40000 respectively.
Most Modbus master devices assume that 30001 or 40001 are subtracted from the defined
address for the registers. The M2x2 subtracts 30000 and 40000, meaning that the addresses
may have to be offset by 1.
Using MODBUS register 40100 (MODBUS table for measurements) the required
register map can be selected. Value “0” is M233 compatible register map. Value “1” is
M231 compatible register map. This selection can also be done during
commissioning using QDSP.
17.2 Register Map for Actual Measurements
M233 Compatible
Register map
M231 Compatible
Register map
Parameter Type
Start End Start End
Voltage U
1
T5 30107 30108 30044 30045
Voltage U
2
T5 30109 30110 30046 30047
Voltage U
3
T5 30111 30112 30048 30049
Average phase Voltage U
~
T5 30113 30114 30042 30043
Phase to phase voltage U
12
T5 30118 30119 30081 30082
Phase to phase voltage U
23
T5 30120 30121 30083 30084
Phase to phase voltage U
31
T5 30122 30123 30085 30086
Average phase to phase Voltage U
pp~
T5 30124 30125 30079 30080
Current I
1
T5 30126 30127 30036 30037
Current I
2
T5 30128 30129 30038 30039
Current I
3
T5 30130 30131 30040 30041
Total Current I T5 30138 30139 30034 30035
Neutral current In T5 30132 30133 30074 30075
Real Power P
1
T6 30142 30143 30020 30021
Real Power P
2
T6 30144 30145 30022 30023
Real Power P
3
T6 30146 30147 30024 30025
Total Real Power P T6 30140 30141 30018 30019
Reactive Power Q
1
T6 30150 30151 30028 30029
Reactive Power Q
2
T6 30152 30153 30030 30031
Reactive Power Q
3
T6 30154 30155 30032 30033
Total Reactive Power Q T6 30148 30149 30026 30027
Apparent Power S
1
T5 30158 30159 30052 30053
Apparent Power S
2
T5 30160 30161 30054 30055
Apparent Power S
3
T5 30162 30163 30056 30057