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Table of Contents
CHAPTER 1 INTRODUCTION.................................................... 1
1.1 USING THE COMMUNICATIONS PORT.......................................... 1
1.2 EIA INTERFACE STANDARDS ..................................................... 2
1.2.1 EIA RS-232 Standard......................................................... 2
1.2.2 EIA RS-422 and EIA RS-485 Standards ............................ 2
1.3 RESPONSE TIME ......................................................................... 2
1.4 SETUP PARAMETERS .................................................................. 3
1.4.1 Handshaking ...................................................................... 3
CHAPTER 2 PRINT MODE.......................................................... 5
2.1 CONFIGURING THE PRINT MODE PARAMETERS .......................... 5
2.2 CABLE CONNECTIONS ................................................................ 5
2.3 FLOW CONTROL ......................................................................... 5
2.4 PRINTOUT FORMAT .................................................................... 6
CHAPTER 3 ASCII COMMUNICATIONS PROTOCOL......... 8
3.1 ASCII FRAMING ....................................................................... 8
3.2 EXCEPTION RESPONSES.............................................................. 9
3.3 ASCII MESSAGE DESCRIPTION ................................................ 10
3.3.1 Read Data Registers ........................................................ 10
3.3.2 Read Basic Setup.............................................................. 12
3.3.3 Write Basic Setup............................................................. 14
3.3.4 Reset/Clear Functions...................................................... 14
3.3.5 Reset Powermeter ............................................................ 15
3.3.6 Read Firmware Version Number ..................................... 15
3.3.7 Read Real Time Clock...................................................... 16
3.3.8 Write Real Time Clock ..................................................... 16
CHAPTER 4 MODBUS COMMUNICATIONS PROTOCOL . 17
4.1 MODBUS FRAMING................................................................ 17
4.1.1 Transmission Mode.......................................................... 17
4.1.2 The RTU Frame Format .................................................. 18
4.1.3 Address Field ................................................................... 18
4.1.4 Function Field.................................................................. 18
4.1.5 Data Field ........................................................................ 19
4.1.6 Error Check Field ............................................................ 19
4.1.7 Data Conversion .............................................................. 21
4.1.8 Data Addressing Modes................................................... 23
4.2 MODBUS MESSAGE FORMATS ............................................... 24
4.2.1 Function 03 - Read Multiple Registers ............................ 24