DECS-200 Modbus
TM
Communication
i
SECTION 7 • MODBUS™ COMMUNICATION
TABLE OF CONTENTS
SECTION 7 • MODBUS COMMUNICATION .........................................................................................7-1
INTRODUCTION ....................................................................................................................................7-1
DECS-200 MODBUS PROTOCOL ........................................................................................................7-1
MESSAGE STRUCTURE.......................................................................................................................7-1
Device Address Field..........................................................................................................................7-1
Function Code Field............................................................................................................................ 7-2
Data Block Field..................................................................................................................................7-2
Error Check Field................................................................................................................................7-2
SERIAL TRANSMISSION DETAILS ...................................................................................................... 7-2
Message Framing and Timing Considerations ................................................................................... 7-3
Error Handling and Exception Responses..........................................................................................7-3
COMMUNICATIONS HARDWARE REQUIREMENTS .......................................................................... 7-3
DETAILED MESSAGE QUERY AND RESPONSE ................................................................................ 7-4
Read Holding Registers...................................................................................................................... 7-4
Preset Multiple Registers.................................................................................................................... 7-4
Preset Single Register (Write Single Holding Register) ..................................................................... 7-5
Error Response................................................................................................................................... 7-5
Loop Back Diagnostic Test (FC= 8) with Diagnostic Sub-function, Return Query Data ....................7-6
Loop Back Diagnostic Test with Diagnostic Sub-function, Restart Communications Option............. 7-6
Loop Back Diagnostic Test with Diagnostic Sub-function, Force Slave to Listen Only Mode............ 7-6
DATA FORMATS ................................................................................................................................... 7-6
Generic Types UI8 and I8...................................................................................................................7-7
Generic Types UI16 and I16...............................................................................................................7-7
Generic Types UI32 and I32...............................................................................................................7-7
Floating Point (R23_32) Data Format................................................................................................. 7-8
CRC ERROR CHECK ............................................................................................................................7-9
DECS-200 MODBUS REGISTER SPACE ............................................................................................. 7-9
DECS-200 REGISTER TABLE.............................................................................................................7-10
Holding Registers for Information Category C1................................................................................ 7-10
Holding Registers for Information Category C2................................................................................ 7-12
Holding Registers for Information Category C3................................................................................ 7-14
Holding Registers for Information Category C4................................................................................ 7-14
Holding Registers for Information Category C5................................................................................ 7-15
Holding Registers for Information Category C6................................................................................ 7-17
Holding Registers for Information Category C7................................................................................ 7-19
Holding Registers for Information Category C8................................................................................ 7-20
Holding Registers for Information Category C9................................................................................ 7-21
Holding Registers for Information Category C10.............................................................................. 7-22
Holding Registers for Information Category C11.............................................................................. 7-23
Holding Registers for Information Category C12.............................................................................. 7-23
Holding Registers for Information Category C13.............................................................................. 7-26
Holding Registers for Information Category C14.............................................................................. 7-27
Holding Registers for Information Category C15.............................................................................. 7-27
Tables
Table 7-1. DECS-200 Communication Settings ........................................................................................ 7-2
Table 7-2. Timing Considerations For 10 Character Bits (8 Data Bits + 1 Start Bit + 1 Stop Bit) ............. 7-3
Table 7-3. Supported Exception Response Codes.................................................................................... 7-3
Table 7-4. Generic Data Types and Description........................................................................................ 7-7
Table 7-5. HR 44005 Contents .................................................................................................................. 7-7
Table 7-6. HR 47003 Mapping................................................................................................................... 7-7
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