Schneider Electric VW3 A3 303 user manual Connecting to the bus, Wiring recommendations

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5. Connecting to the bus

5. 1. Wiring recommendations

•Use Telemecanique-approved cables and wiring accessories to ensure good transmission quality (matched impedance, immunity, shielding connection, etc.).

•Keep the Modbus cable away from the power cables (30 cm minimum).

•Be sure to cross the Modbus cable and the power cables at right angles.

•Whenever possible, connect the bus cable shielding to the protective ground, e.g., to the ground of each device if this ground is connected to the protective ground.

•Install a line terminator at both ends of the line.

•Ensure the correct line polarization.

•Connect the common polarity ("Common" signal) to the protective ground at one or more points on the bus.

For more information, please refer to the TSX DG KBL E guide: "Electromagnetic compatibility of industrial networks and fieldbuses".

5. 2. Modbus RS485 standard

The characteristics and accessories mentioned in this section ("5. Connecting to the bus") comply with the Modbus standard. Other non-Modbus-standard RS485 wiring diagrams are possible. Please see the Appendix for further information.

The latest generation of Telemecanique equipment conforms to Modbus (2-wire RS485).

Main characteristics:

Maximum length of bus	1000 m at 19,200 bps
Maximum number of stations	32 stations, i.e., 31 slaves (without repeater)

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Contents Altivar Contents Electric shock will result in death or serious injury Before you beginDocumentation structure Installation ManualProgramming Manual Communication Parameters ManualIntroduction PresentationNotation Installing the card in the drive Hardware setupReceipt Hardware descriptionSwitch coding Choosing polarizationCoding the address 1234 AddressConnecting to the bus Wiring recommendationsModbus RS485 standard Connection via RJ45 wiring system Connection accessoriesConnection cables Type of master Master interface Description Catalog number Connection cables for the masterTWD XCA RJ030 TSX SCP CMDescription Catalog Number Subscriber socket Connection via junction boxesRS485 double shielded twisted pair CablesTSX P ACC TSX CSA500Communication parameters ConfigurationControl via Modbus in I/O profile Control CommandControl via Modbus or the terminals in I/O profile Parameter Value CommentControl via Modbus or the terminals in Drivecom profile Control via Modbus in Drivecom profileConfiguration Communication scanner Example of configuration via the graphic display terminalRDY NET COM. Scanner InputCOM. Fault Management Communication faultsMonitored parameters CONFIG. COMM. MAPFormat Format Range Terminal displayChecking the address DiagnosticsLEDs Green RUN Red ERR Meaning Corrective actionCommunication MAP RUN NETCOM. Scanner Input MAP COM Scan Output MAP CMD. Word ImageInput variable Scanner parameter Output variable Scanner parameterCOM Scan Output MAP Card fault Communication faultModbus protocol PrincipleSlave Slave j Slave k Ascii mode RTU modeModes Slave address Function code DataModbus functions available Read Holding/Input Registers 3/4Code Modbus name Description Broadcast Size of data Write Single Register Diagnostics Write Multiple Registers 16 = 16#10 Get Comm Event Counter 11 = 16#0BRead/Write Multiple Registers 23 = 16#17 Machine Read Device Identification 43 = 16#2BMEI Example of positive responseOutput variables Logic address Default assignment Input variables Logic address Default assignmentCode Modbus name Description Size of data Input variable address Logic address Default value Parameter Logic ReadParameter Logic Parameter assigned Output controlInput monitoring Value Parameter assignedCode Error code Exception responsesResponse Logic address Parameter Value Read non-existent or protected parametersRS485 standard AppendixMaster Modbus 2-wire standard schematicModbus 4-wire standard schematic Uni-Telway schematic Type of trunk cable Cable with 1 shielded twisted pair Wire Jbus schematicCreating a Modbus bus using non-standard equipment Different scenariosRecommendations Example Calculating the polarizationCard connector pinout RS485 schematic for the cardContact no. Signal SUB-DAtv71ModbusJbusENV1 2005-05