Schneider Electric LXM32M manual Basics, Modbus TCP technology, Function principle, Bus topology

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LXM32M	3 Basics

3 Basics

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3.1Modbus TCP technology

3.1.1Function principle

Modbus TCP is an Ethernet fieldbus. Modbus TCP describes the transmission of the Modbus protocol via the Ethernet interface and the TCP/IP transport and network layers.

The Modbus TCP client (master) connects to the Modbus TCP server (slave). Once the connection is established, the client sends Modbus requests to the server. These requests are processed by the server.

The result is returned to the client as a Modbus response.

The Modbus TCP services are identical to the Modbus RTU services.

3.1.2Bus topology

Star and tree topologies can be used. It is possible to use hubs or switches. In the case of high bus loads with many devices, it is recom- mended to use a switches.

The maximum length of a segment is 100 m. A segment consists of devices and hubs. A network can be subdivided into several segments by means of gateways or switches. Short cables and a star topology are recommended to achieve a fast bus cycle.

The transmission rate is 10 or 100 MBit/s in half-duplex mode. If switches are used, transmission is also possible in full duplex mode.

0198441113843, V1.01, 01.2012

Modbus-TCP module

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Contents LXM32M Important information Table of contents Diagnostics and troubleshooting Accessories and spare parts LXM32M About this manual Further reading Fieldbus products on the network IntroductionLXM32M Before you begin safety information Qualification of personnelIntended use Hazard categories Basic information Standards and terminology Bus topology BasicsModbus TCP technology Function principleClient / server model Network service SnmpStructure of a Modbus message Modbus TCP protocolField Length Description Mbap headerConnection management Modbus TCP communicationExcep Name Description Tion Code Modbus response to a Modbus requestAddress Value Reading and writing parameters4 I/O scanning to Drive Profile Lexium Byte Meaning Data type Parameter address 4.1 I/O scanning OutputBit Meaning 4.2 I/O scanning InputInputs Bit Signal Factory settingParameter channel Ctrl Subindex Index Modbus services Function Code Function Code 3 Read Multiple RegistersField Bytes Value Meaning Sub-function Code Diagnostics function Function Code 8 DiagnosticsFunction Code 16 Write Multiple Registers Function Code 23 ReadWrite Multiple Registers Object ID Object name Value Function Code 43 Encapsulated Interface TransportExample of Function Code ExamplesLXM32M Installation Installation of the moduleDescription Order no Pin Signal Meaning Electrical installationCommissioning the device CommissioningSwitching on the device Power stage supply is switched off First SetupDhcp / dhcP Dhcp Bootp / boot BootpManual assignment of the network address Manual / MAnu ManualIP address Ethernet module, byte Assignment of the network address via Bootp Assignment of the network address via Dhcp Setting the protocol Setting the transmission rateSet the IP address of the gateway with the parameters Setting the gatewayMaster with Word Swap Setting I/O-Scanning Setting the master for I/O scanningActivating I/O scanning Setting the mapping for I/O scanning PLC Setting communication monitoring for I/O scanning Setting the web server0198441113843, V1.01 Operation Operating states Indication of the operating stateBit Name Meaning Bit Name Meaning Operating state Changing the operating stateIndicating and monitoring the operating mode Operating modesBit Name Description Bit Name Description Starting and changing an operating modeMODE+ACTION Overview of operating modesOperating mode Jog Operating mode Electronic Gear 24 h Operating mode Profile Torque23 h Operating mode Profile VelocityOperating mode Profile Position Operating mode Homing LXM32M6 Operation Operating mode Motion SequenceWeb server Extended settingsUser interface Main menu Submenu ContentFTP server Accessing the FTP serverFDR service Fast Device Replacement LXM32M Fieldbus communication error diagnostics Diagnostics and troubleshootingColor Status Meaning Status LEDsMeaning for EtherNet/IP Meaning for Modbus TCP ColorError indication Excep Name Description Tion Code LXM32M Cables Accessories and spare partsLXM32M Units and conversion tables GlossaryMoment of inertia TemperatureRotation TorqueTerms and Abbreviations LXM32M Index LXM32M