Schneider Electric VW3 A3 303 user manual Modbus 2-wire standard schematic, Master

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9. Appendix

9. 2. Modbus 2-wire standard schematic

The standard schematic corresponds to the Modbus specification published in 2002 on www.modbus.org (Modbus_over_serial_line_V1.pdf, Nov 2002) and, in particular, to the 2-wire multipoint serial bus schematic.

The Modbus card (VW3 A3 303) conforms to this specification.

Schematic diagram:

Master
R	G	5 V
R		5 V
		650 Ω
650 Ω
	0 V
D1
120 Ω		120 Ω
1n F		1n F
D0
Common

R

G

Slave 1

R

G

Slave n

Type of trunk cable	Shielded cable with 1 twisted pair and at least a 3rd conductor
Maximum length of bus	1000 m at 19200 bps with the Telemecanique TSX CSAp00 cable

Maximum number of stations (without	32 stations, i.e., 31 slaves
repeater)
Maximum length of tap links	• 20 m for one tap link
	• 40 m divided by the number of tap links on a multiple junction box
Bus polarization	• One 450 to 650 Ω pull-up resistor to the 5 V (650 Ω or thereabouts recommended)
	• One 450 to 650 Ω pull-down resistor to the Common (650 Ω or thereabouts
	recommended)
	This polarization is recommended for the master.
Line termination	One 120 Ω 0.25 W resistor in series with a 1nF 10 V capacitor

Common polarity	Yes (Common), connected to the protective ground at one or more points on the bus

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Contents Altivar Contents Before you begin Electric shock will result in death or serious injuryInstallation Manual Documentation structureProgramming Manual Communication Parameters ManualPresentation IntroductionNotation Hardware setup Installing the card in the driveReceipt Hardware descriptionChoosing polarization Switch codingCoding the address Address 1234Wiring recommendations Connecting to the busModbus RS485 standard Connection accessories Connection via RJ45 wiring systemConnection cables Connection cables for the master Type of master Master interface Description Catalog numberTWD XCA RJ030 TSX SCP CMConnection via junction boxes Description Catalog Number Subscriber socketRS485 double shielded twisted pair CablesTSX CSA500 TSX P ACCConfiguration Communication parametersControl Command Control via Modbus in I/O profileControl via Modbus or the terminals in I/O profile Parameter Value CommentControl via Modbus in Drivecom profile Control via Modbus or the terminals in Drivecom profileConfiguration Example of configuration via the graphic display terminal Communication scannerRDY NET COM. Scanner InputCommunication faults COM. Fault ManagementCONFIG. COMM. MAP Monitored parametersFormat Format Range Terminal displayDiagnostics Checking the addressLEDs Green RUN Red ERR Meaning Corrective actionRUN NET Communication MAPCOM. Scanner Input MAP COM Scan Output MAP CMD. Word ImageOutput variable Scanner parameter Input variable Scanner parameterCOM Scan Output MAP Communication fault Card faultPrinciple Modbus protocolSlave Slave j Slave k RTU mode Ascii modeModes Slave address Function code DataRead Holding/Input Registers 3/4 Modbus functions availableCode Modbus name Description Broadcast Size of data Write Single Register Diagnostics Get Comm Event Counter 11 = 16#0B Write Multiple Registers 16 = 16#10Read/Write Multiple Registers 23 = 16#17 Read Device Identification 43 = 16#2B MachineExample of positive response MEIInput variables Logic address Default assignment Output variables Logic address Default assignmentCode Modbus name Description Size of data Parameter Logic Read Input variable address Logic address Default valueParameter Logic Output control Parameter assignedInput monitoring Value Parameter assignedException responses Code Error codeResponse Read non-existent or protected parameters Logic address Parameter ValueAppendix RS485 standardModbus 2-wire standard schematic MasterModbus 4-wire standard schematic Uni-Telway schematic Wire Jbus schematic Type of trunk cable Cable with 1 shielded twisted pairDifferent scenarios Creating a Modbus bus using non-standard equipmentRecommendations Calculating the polarization ExampleRS485 schematic for the card Card connector pinoutContact no. Signal SUB-DAtv71ModbusJbusENV1 2005-05