Emotron VS10 - Modbus RTU; Modbus RTU Introduction; Modbus RTU Node Address

236 01-6203-01R3, CG Drives & Automation
8.6. Modbus RTU
Modbus is an internationally approved, asynchronous, serial communication protocol,
designed for commercial and industrial automation applications.
• Detailed information on the Modbus can be found on the web page of the
international Modbus Organization, USA, who also further develop the Modbus
protocol: http:// www.modbus.org
• Information about the dimensioning of a Modbus network can be found in the
configuration document for the inverter.
Preconditions
• Control Unit (CU) des Inverters ist mit Modbus/CANopen ausgestattet.
• Modbus/CANopen-Umschalter auf der Frontseite des Inverters ist in Stellung
"Modbus".
8.6.1. Modbus RTU introduction
• The process of data transmission distinguishes between three different operating
modes: Modbus ASCII, Modbus RTU, and Modbus TCP. This chapter describes the
Modbus RTU operating mode ("Remote Terminal Unit").
• The Modbus protocol is based on a master/slave architecture where the inverter
always works as slave.
• The Modbus network only permits one master (at a time) sending commands and
requests. The master is also the sole instance to be allowed to initiate Modbus
communication. No direct communication takes place between the slaves.
• The physical interface corresponds to TIA/EIA-485-A which is very common and
suitable for the industrial environment. This interface enables baud rates from 2400 to
• 115200 kbps.
• The inverter supports Modbus function codes 3, 6, 16 (0x10) and 23 (0x17).
8.6.2. Modbus RTU node address
Each network node must be provided with a unique node address.
Details
• The node address can be set in 0x2321:001 (P510.01).
• The setting that is active when the inverter is switched on is the effective setting.
• The node address 0 is reserved for messages to all nodes ("Broadcast") .
• The active node address is shown in 0x2322:001 (P511.01).
Parameter
Name / value range / [default setting]
Info
0x2321:001
(P510.01)
Modbus settings: Node ID
(Modbus sett.: Node ID)
1 ... [1] ... 247
Setting of the node address.
A change in the node address only becomes effective after a restart of
Modbus communication.
0x2323
(P509.00)
Modbus switch position
(Modbus switch)
Read only
Display of the DIP switch setting at the last mains power-on.