Modicon Modbus Protocol Reference Guide - The Modbus ...

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Chapter 2 Data and Control Functions . . . . . . . . . . . . . 17Modbus Function Formats . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18How Numerical Values are Expressed . . . . . . . . . . . . . . . . . . . . . . 18Data Addresses in Modbus Messages . . . . . . . . . . . . . . . . . . . . . . 18Field Contents in Modbus Messages . . . . . . . . . . . . . . . . . . . . . . . 18Field Contents on Modbus Plus . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20Function Codes Supported by Controllers . . . . . . . . . . . . . . . . . . . . . . . . . 2201 Read Coil Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2402 Read Input Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2603 Read Holding Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2804 Read Input Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3005 Force Single Coil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3206 Preset Single Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3407 Read Exception Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3611 (0B Hex) Fetch Comm Event Ctr . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3812 (0C Hex) Fetch Comm Event Log . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4015 (0F Hex) Force Multiple Coils . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4416 (10 Hex) Preset Multiple Regs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4617 (11 Hex) Report Slave ID . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4820 (14Hex) Read General Reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5821 (15Hex) Write General Reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6222 (16Hex) Mask Write 4X Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6623 (17Hex) Read/Write 4X Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6824 (18Hex) Read FIFO Queue . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70viiiContentsPI–MBUS–300
Chapter 3 Diagnostic Subfunctions . . . . . . . . . . . . . . . . 73Function 08 – Diagnostics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74Diagnostic Codes Supported by Controllers . . . . . . . . . . . . . . . . . . . . . . . . 76Diagnostic Subfunctions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7700 Return Query Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7701 Restart Communications Option . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7702 Return Diagnostic Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7803 Change ASCII Input Delimiter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8104 Force Listen Only Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8110 (0A Hex) Clear Counters and Diagnostic Register . . . . . . . . . . . . . . . 8111 (0B Hex) Return Bus Message Count . . . . . . . . . . . . . . . . . . . . . . . . . . 8212 (0C Hex) Return Bus Communication Error Count . . . . . . . . . . . . . . . 8213 (0D Hex) Return Bus Exception Error Count . . . . . . . . . . . . . . . . . . . . 8214 (0E Hex) Return Slave Message Count . . . . . . . . . . . . . . . . . . . . . . . . 8315 (0F Hex) Return Slave No Response Count . . . . . . . . . . . . . . . . . . . . 8316 (10 Hex) Return Slave NAK Count . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8317 (11 Hex) Return Slave Busy Count . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8418 (12 Hex) Return Bus Character Overrun Count . . . . . . . . . . . . . . . . . 8419 (13 Hex) Return IOP Overrun Count (884) . . . . . . . . . . . . . . . . . . . . . 8420 (14 Hex) Clear Overrun Counter and Flag (884) . . . . . . . . . . . . . . . . . 8521 (15 Hex) Get/Clear Modbus Plus Statistics . . . . . . . . . . . . . . . . . . . . . 86Modbus Plus Network Statistics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87Appendix A Exception Responses . . . . . . . . . . . . . . . . . 93Exception Responses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94Exception Codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96Appendix B Application Notes . . . . . . . . . . . . . . . . . . . . . 99Maximum Query/Response Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . 100Estimating Serial Transaction Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106Notes for the 584 and 984A/B/X . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108Appendix C LRC/CRC Generation . . . . . . . . . . . . . . . . . 109LRC Generation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110CRC Generation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112PI–MBUS–300 Contents ix
Page 1 and 2: ModiconModbus ProtocolReference Gui
Page 3 and 4: PrefaceThis guide is written for th
Page 5: ContentsChapter 1 Modbus Protocol .
Page 9 and 10: Figure 28 Force Multiple Coils - Qu
Page 11 and 12: Introducing Modbus ProtocolModicon
Page 13 and 14: Introducing Modbus Protocol (Contin
Page 15 and 16: The Two Serial Transmission ModesCo
Page 17 and 18: Modbus Message FramingIn either of
Page 19 and 20: Modbus Message Framing (Continued)H
Page 21 and 22: Modbus Message Framing (Continued)C
Page 23 and 24: Error Checking MethodsStandard Modb
Page 25 and 26: Error Checking Methods (Continued)C
Page 27 and 28: Modbus Function FormatsHow Numerica
Page 29 and 30: Modbus Function Formats (Continued)
Page 31 and 32: Function Codes Supported by Control
Page 33 and 34: 01 Read Coil StatusDescriptionReads
Page 35 and 36: 02 Read Input StatusDescriptionRead
Page 37 and 38: 03 Read Holding RegistersDescriptio
Page 39 and 40: 04 Read Input RegistersDescriptionR
Page 41 and 42: 05 Force Single CoilDescriptionForc
Page 43 and 44: 06 Preset Single RegisterDescriptio
Page 45 and 46: 07 Read Exception StatusDescription
Page 47 and 48: 11 (0B Hex) Fetch Comm Event Counte
Page 49 and 50: 12 (0C Hex) Fetch Comm Event LogDes
Page 51 and 52: 12 (0C Hex) Fetch Comm Event Log (C
Page 53 and 54: 15 (0F Hex) Force Multiple CoilsDes
Page 55 and 56: 16 (10 Hex) Preset Multiple Registe
Page 57 and 58:
17 (11 Hex) Report Slave IDDescript
Page 59 and 60:
17 (11 Hex) Report Slave ID (Contin
Page 61 and 62:
Page 63 and 64:
Page 65 and 66:
Page 67 and 68:
20 (14Hex) Read General ReferenceDe
Page 69 and 70:
20 (14 Hex) Read General Reference
Page 71 and 72:
21 (15Hex) Write General ReferenceD
Page 73 and 74:
21 (15 Hex) Write General Reference
Page 75 and 76:
22 (16Hex) Mask Write 4X RegisterDe
Page 77 and 78:
23 (17Hex) Read/Write 4X RegistersD
Page 79 and 80:
24 (18Hex) Read FIFO QueueDescripti
Page 81 and 82:
Chapter 3Diagnostic SubfunctionsMod
Page 83 and 84:
QueryHere is an example of a reques
Page 85 and 86:
Diagnostic Subfunctions00 Return Qu
Page 87 and 88:
484 Diagnostic RegisterBitDescripti
Page 89 and 90:
03 Change ASCII Input DelimiterThe
Page 91 and 92:
14 (0E Hex) Return Slave Message Co
Page 93 and 94:
20 (14 Hex) Clear Overrun Counter a
Page 95 and 96:
Modbus Plus Network StatisticsWord
Page 97 and 98:
Word Byte Meaning18 LO Bad internal
Page 99 and 100:
Word Bits Meaning50 LO Program slav
Page 101 and 102:
Exception ResponsesExcept for broad
Page 103 and 104:
Exception CodesCode Name Meaning01
Page 105 and 106:
Appendix BApplication NotesThis App
Page 107 and 108:
484These values are for an 8K contr
Page 109 and 110:
884Function Description Query Respo
Page 111 and 112:
Function Description Query Response
Page 113 and 114:
( C ) Continued:For 484 controllers
Page 115 and 116:
Appendix CLRC/CRC GenerationLRC Gen
Page 117 and 118:
ExampleAn example of a C language f
Page 119 and 120:
6. Repeat Steps 2 through 5 for the
Page 121:
High-Order Byte Table/* Table of CR
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