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9469300991 Rev A
iii
DGC-2020HD Modbus
™ Protocol
Contents
General Information .................................................................................................................................... 1
Message Structure .................................................................................................................................... 1
Device Address Field ................................................................................................................................. 1
Function Code Field .................................................................................................................................. 1
Data Block Field ........................................................................................................................................ 2
Error Check Field ....................................................................................................................................... 2
Modbus Modes of Operation ..................................................................................................................... 2
Modbus Over Serial Line ........................................................................................................................... 2
Modbus on TCP/IP .................................................................................................................................... 3
Error Handling and Exception Responses ................................................................................................ 4
via Ethernet .......................................................................................................... 5
Detailed Message Query and Response for RTU Transmission Mode .................................................... 5
Read Holding Registers............................................................................................................................. 5
Return Query Data .................................................................................................................................... 5
Restart Communications Option ............................................................................................................... 6
Listen Only Mode ....................................................................................................................................... 6
Preset Multiple Registers........................................................................................................................... 6
Preset Single Register ............................................................................................................................... 7
Data Formats ............................................................................................................................................. 8
Floating Point Data Format (Float) ............................................................................................................ 8
Long Integer Data Format (Uint32, Int32, and IP Address) ....................................................................... 9
Integer Data Format (Uint16) or Bit-Mapped Variables in Uint16 Format ................................................. 9
Short Integer Data Format/Byte Character Data Format (Uint8)............................................................... 9
String Data Format (String) ....................................................................................................................... 9
CRC Error Check ..................................................................................................................................... 10
Default Register Table .............................................................................................................................. 11
General .................................................................................................................................................... 11
Binary Points ........................................................................................................................................... 21
Bias Control ............................................................................................................................................. 50
Breaker Settings ...................................................................................................................................... 53
Bus Condition .......................................................................................................................................... 56
DGC Settings ........................................................................................................................................... 60
Pulse Outputs .......................................................................................................................................... 62
Control Settings ....................................................................................................................................... 62
Global Settings ........................................................................................................................................ 63
Configuration ........................................................................................................................................... 64
Remote Module Settings ......................................................................................................................... 69
Metering ................................................................................................................................................. 124
Protection Settings ................................................................................................................................ 133
Legacy Register Table ............................................................................................................................ 229
Breaker Management ............................................................................................................................ 229
Bias Control Settings ............................................................................................................................. 230
Pulse Outputs ........................................................................................................................................ 233
Bus Condition Detection ........................................................................................................................ 233
Senders ................................................................................................................................................. 234
System Configuration and Status .......................................................................................................... 235
Control ................................................................................................................................................... 238
Communication ...................................................................................................................................... 239
Protection .............................................................................................................................................. 239
Alarms.................................................................................................................................................... 243
Metering ................................................................................................................................................. 244
Revision History ...................................................................................................................................... 309
