Modbus Communication Protocol - Iskra MT440 User Manual

7.1 Modbus communication protocol

Modbus is enabled via RS232 and RS485 or USB. The response is the same type as the request.
Two versions of MODBUS register tables are available:
−
VERSION 1: Compatibility with advanced family of transducers (MT500)
−
VERSION 2: Compatibility with previous family of transducers (MI400)
Modbus
Modbus protocol enables operation of device on Modbus networks. For device with serial
communication the Modbus protocol enables point to point (for example Device to PC)
communication via RS232 communication and multi drop communication via RS485
communication. Modbus protocol is a widely supported open interconnect originally designed by
Modicon.
The memory reference for input and holding registers is 30000 and 40000 respectively.
VERSION1:
Register table for the actual measurements
Parameter
Reserved
Frequency
U1
U2
U3
Uavg (phase to neutral)
ϕ 12 (angle between U1 and U2)
ϕ 23 (angle between U2 and U3)
ϕ 31 (angle between U3 and U1)
U12
U23
U31
Uavg (phase to phase)
I1
I2
I3
INc
INm - reserved
Iavg
Σ I
Active Power Total (Pt)
Active Power Phase L1 (P1)
Active Power Phase L2 (P2)
Active Power Phase L3 (P3)
User's Manual
MODBUS
Register
Start End
30101 30104
30105 30106
30107 30108
30109 30110
30111 30112
30113 30114
30115
30116
30117
30118 30119
30120 30121
30122 30123
30124 30125
30126 30127
30128 30129
30130 30131
30132 30133
30134 30135
30136 30137
30138 30139
30140 30141
30142 30143
30144 30145
30146 30147
Appendix A: Modbus protocol
Type
T5
T5
T5
T5
T5
T17
T17
T17
T5
T5
T5
T5
T5
T5
T5
T5
T5
T5
T5
T6
T6
T6
T6
41