Schweitzer Engineering Laboratories SEL-2020 - APPENDIX G: MODBUS PROTOCOL; Overview; SETTINGS

ii Appendices Table of Contents Date Code 20010518
SEL-2020 Instruction Manual
APPENDIX G: MODBUS PROTOCOL
Overview......................................................................................................................................G-1
Settings.........................................................................................................................................G-1
Hardware Connections and RTS Line Usage ..............................................................................G-1
Data Access Considerations.........................................................................................................G-2
Timing..........................................................................................................................................G-2
Function Codes ............................................................................................................................G-3
Message Framing .................................................................................................................G-3
Read Coil Status (Function Code 01h).................................................................................G-3
Read Input Status (Function Code 02h) ...............................................................................G-4
Read Holding Register (Function Code 03h).......................................................................G-4
Read Input Register (Function Code 04h)............................................................................G-5
Force Single Coil (Function Code 05h) ...............................................................................G-6
Preset Single Register (Function Code 06h) ........................................................................G-7
Preset Multiple Registers (Function Code 10h)...................................................................G-7
Report Slave ID (Function Code 11h)..................................................................................G-7
Error Handling......................................................................................................................G-9
Master Device Configuration Considerations......................................................................G-9
"Job Done" Example for Modbus ................................................................................................G-9
Example #1: Simple Meter Data Access.............................................................................G-9
Example #2: Accessing Centralized Data .........................................................................G-12
APPENDIX H: SEL-2020 CONFIGURATION AND FAST OPERATE
COMMANDS
Overview......................................................................................................................................H-1
Device Definition.........................................................................................................................H-1
Fast Operate Configuration.........................................................................................................H-1
Fast Operate Commands .............................................................................................................H-2
APPENDIX I: DISTRIBUTION NETWORK PROTOCOL (DNP)
V3.00
Overview....................................................................................................................................... I-1
Installation..................................................................................................................................... I-1
Configuration ................................................................................................................................ I-1
Data-Link Operation.............................................................................................................. I-1
Data Access Method.............................................................................................................. I-2
Device Profile ............................................................................................................................... I-2
Device Profile Document ...................................................................................................... I-2
Object Table.................................................................................................................................. I-5
Object Definitions ......................................................................................................................... I-8
Input Objects ......................................................................................................................... I-8
Output Objects ...................................................................................................................... I-8
Internal Indication Object.................................................................................................... I-11