Lenze i550

12.12 Modbus RTU
Modbus is an internaonally approved, asynchronous, serial communicaon protocol,
designed for commercial and industrial automaon applicaons.
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Detailed informaon on the Modbus can be found on the web page of the internaonal
Modbus Organizaon, USA, who also further develop the Modbus protocol: hp://
www.modbus.org
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Informaon about the dimensioning of a Modbus network can be found in the congura-
on document for the inverter.
Precondions
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The control unit (CU) of the inverter is provided with Modbus.
Details
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The process of data transmission disnguishes between three dierent operang modes:
Modbus ASCII, Modbus RTU, and Modbus TCP. This chapter describes the Modbus RTU
operang mode ("Remote Terminal Unit").
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The Modbus protocol is based on a master/slave architecture where the inverter always
works as slave.
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The Modbus network only permits one master sending commands and requests. The mas-
ter is also the sole instance to be allowed to iniate Modbus communicaon. No direct
communicaon takes place between the slaves.
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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.
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The inverter supports Modbus funcon codes 3, 6, 16 (0x10) and 23 (0x17).
Typical topology
Line
A1 A2 A3 An
X216 X216 X216 X216
120 120 120 120
COM COM COM COM
TB TB TB TB
TA TA TA TA
Conguring the network
Modbus RTU
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