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Table of Contents
1 GENERAL ............................................................................................. 4
2 MODBUS FRAMING ............................................................................. 5
2.1 Transmission Mode ................................................................................................ 5
2.2 The RTU Frame Format ......................................................................................... 5
2.3 Address Field.......................................................................................................... 5
2.4 Function Field ......................................................................................................... 5
2.5 Data Field ............................................................................................................... 6
2.6 Error Check Field.................................................................................................... 6
3 MODBUS MESSAGE FORMATS ......................................................... 7
3.1 Function 03 - Read Multiple Registers ................................................................... 7
3.2 Function 04 - Read Multiple Registers ................................................................... 7
3.3 Function 06 - Write Single Register........................................................................ 7
3.4 Function 16 - Write Multiple Registers ................................................................... 8
3.5 Function 08 - Loop-back Communications Test..................................................... 8
3.6 Exception Responses............................................................................................. 9
4 PROTOCOL IMPLEMENTATION ....................................................... 10
4.1 Modbus Register Addresses ................................................................................ 10
4.2 Data Formats ........................................................................................................ 10
4.2.1 16-bit Integer Format .................................................................................... 10
4.2.2 32-bit Modulo 10000 Format ........................................................................ 12
4.2.3 32-bit Long Integer Format ........................................................................... 12
4.3 User Assignable Registers ................................................................................... 12
5 POWERMETER REGISTERS DESCRIPTION.................................... 14
5.1 Basic Data Registers Set...................................................................................... 14
5.2 Basic Setup........................................................................................................... 15
5.3 User Selectable Options Setup ............................................................................ 16
5.4 Communications Setup ........................................................................................ 16
5.5 Reset/Synchronization Registers ......................................................................... 16
5.6 Instrument Status.................................................................................................. 17
5.7 Extended Status ................................................................................................... 17
5.8 Extended Data Registers...................................................................................... 19
5.9 Alarm/Event Setpoints .......................................................................................... 24
5.10 Pulsing Setpoints ................................................................................................ 26
5.11 Relay Operation Control ..................................................................................... 26
5.12 Min/Max Log ....................................................................................................... 27
