MODBUS TCP SPECIFICATION v1.0

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文件名称：MODBUS TCP SPECIFICATION v1.0
文件大小：69KB
文件格式：PDF
更新时间：2014-03-29 05:38:40
MODBUS TCP Contents Contents ............................................................................................................................................................................2 1. Status of this specification .........................................................................................................................................3 2. Overview........................................................................................................................................................................3 2.1 Connection-oriented..............................................................................................................................................3 2.2 Data encoding ........................................................................................................................................................4 2.3 Interpretation of reference numbers .....................................................................................................................4 2.4 Implied length philosophy....................................................................................................................................5 3. Conformance class summary ......................................................................................................................................5 3.1 Class 0......................................................................................................................................................................5 3.2 Class 1......................................................................................................................................................................5 3.3 Class 2......................................................................................................................................................................6 3.4 Machine/vendor/network specific functions .....................................................................................................7 4. Protocol structure.........................................................................................................................................................7 5. Protocol reference by conformance class..................................................................................................................8 5.1 Class 0 commands detail.......................................................................................................................................9 5.1.1 Read multiple registers (FC 3)........................................................................................................................9 5.1.2 Write multiple registers (FC 16).....................................................................................................................9 5.2 Class 1 commands detail.....................................................................................................................................10 5.2.1 Read coils (FC 1)...........................................................................................................................................10 5.2.2 Read input discretes (FC 2)..........................................................................................................................10 5.2.3 Read input registers (FC 4) ..........................................................................................................................11 5.2.4 Write coil (FC 5)............................................................................................................................................11 5.2.5 Write single register (FC 6)..........................................................................................................................12 5.2.6 Read exception status (FC 7).......................................................................................................................13 5.3 Class 2 commands detail.....................................................................................................................................13 5.3.1 Force multiple coils (FC 15)..........................................................................................................................13 5.3.2 Read general reference (FC 20)....................................................................................................................14 5.3.3 Write general reference (FC 21)...................................................................................................................15 5.3.4 Mask write register (FC 22)..........................................................................................................................16 5.3.5 Read/write registers (FC 23).........................................................................................................................16 5.3.6 Read FIFO queue (FC 24) .............................................................................................................................17 6. Exception codes..........................................................................................................................................................17 Appendices .....................................................................................................................................................................19 A. Client and Server Implementation Guidance..........................................................................................................19 A.1 Client design........................................................................................................................................................19 A.2 Server design.......................................................................................................................................................20 A.2.1 Multithreaded server..................................................................................................................................20 A.2.2 Single -threaded server...............................................................................................................................21 A.3 Required and expected performance.................................................................................................................22 B. Data Encoding for non-word data...........................................................................................................................23 B.1 Bit numbers within a word .................................................................................................................................23 B.2 Multi-word quantities.........................................................................................................................................24 B.2.1 984 Data Types ............................................................................................................................................24 B.2.2 IEC-1131 data types.....................................................................................................................................25