Vacon NXL series User Manual

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Vacon NXL series User Manual Manual pdf 75 page image

Control keypad vacon • 7524-hour support: +358-40-8371 150 • Email: vacon@vacon.com 77.4.7 Modbus interfaceNXL has a built-in Modbus RTU bus interface. The signal level of the interface is in accordance withthe RS-485 standard.Protocol: Modbus RTUBaud rates: 300, 600, 1200, 2400, 4800,9600, 19200, 38700, 57600 (bit/s)Signal level: RS-485 (TIA/EIA-485-A)Input impedance: 2 kΩ7.4.7.1 Modbus RTU protocolModbus RTU protocol is a simple but effective fieldbus protocol. Modbus network has a bustopology, where every device has an individual address. With the help of the individual bus addressesthe commands are directed to the single devices within the network. Modbus supports alsobroadcast -type messages, that are received by every device of the bus. Broadcast messages aresent to the address ’0’ which is reserved for these messages.The protocol includes CRC error detection and parity check for preventing the handling of messagescontaining errors. In Modbus the data is transferred in hex mode asynchronically and a break ofapproximately 3,5 characters is used as an end character. The length of the break depends on theused baud rate.FunctioncodeFunction name Address Broadcastmessages03 Read Holding Register All ID numbers No04 Read Input Register All ID numbers No06 Preset Single Register All ID numbers Yes16 Preset Multiple Register All ID numbers YesTable 7-12. Modbus commands supported by NXLRS-485 Transceiver Control terminalRS-485 ARS-485 BTerminal resistor 120ΩX7 -> MF2-MF3X9 -> MF4-MF6