Operation In The Modbus Rtu Network - Slave Mode; Available Functions And Response Times; Memory Map - WEG CFW100 User Manual

5 OPERATION IN THE MODBUS RTU NETWORK – SLAVE MODE
The CFW100 frequency inverter has the following characteristics when operated in Modbus RTU network:
Network connection via RS485 serial interface.

Address, communication rate and byte format defined by means of parameters.

It allows the device programming and control via the access to parameters.

5.1

AVAILABLE FUNCTIONS AND RESPONSE TIMES

In the Modbus RTU specification are defined the functions used to access different types of data. In the
CFW100 the parameters have been defined as being holding type registers. In order to access those data the
following services (or functions) have been made available:
Read Holding Registers

Description: reading of register blocks of the holding register type.
Function code: 03.
Read Input Registers

Description: reading of register blocks of the input register type.
Function code: 04.
Write Single Register

Description: writing in a single register of the holding type.
Function code: 06.
Write Multiple Registers

Description: writing in register blocks of the holding register type.
Function code: 16.
Read Device Identification

Description: identification of the device model.
Function code: 43.
The response time, from the end of transmission of the master until the response of the slave, ranges from 2 to
10 ms for any of the functions above.
5.2

MEMORY MAP

The CFW100 Modbus communication is based on the reading/writing of the equipment parameters. All the
drive parameters list is made available as holding type 16-bit registers. The data addressing is done with the
offset equal to zero, which means that the parameter number corresponds to the register number. The following
table illustrates the parameters addressing, which can be accessed as holding type register.
It is necessary to know the inverter list of parameters to be able to operate the equipment. Thus, it is possible to
identify what data are needed for the status monitoring and the control of the functions. The main parameters
are:
Monitoring (reading):
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Operation in the Modbus RTU Network – Slave Mode
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Table 5.1: Modbus RTU Memory Map
Parameter number
P0000
P0001
P0100
Modbus data address
Decimal Hexadecimal
0 0000h
1 0001h
100 0064h