Yaskawa V7 Enhanced Memobus - Manual (Page 2)

Date: 07/01/04, Rev: 04-07 Page 2 of 2 TM.V7SW.034
Background:
All inverters in Yaskawa’s current product line support Memobus communication protocol, which is based
on Modbus RTU. However, not every function code of Modbus is supported by Memobus, which can
cause incompatibility issues with certain HMIs and PLCs.
Specifically, Modbus function code 06H (single register write) is not supported on standard Yaskawa
product. Some HMI/PLC software configuration programs do not permit manual selection of the function
code. Therefore, if the user needs to write one word of data to the inverter, function code 06H will
automatically be selected instead of function code 10H (multiple register write). Therefore, the inverter
will not recognize the query message.
This software adds support for function code 06H to the V7. The correct version must be selected based
on inverter capacity as shown:
VSP018090
< 4.0kW
VSP018100 5.5/7.5kW
Detailed Description of Functionality:
Support for function code 06H is added. The format for the message is shown below.
(Example)
Query Message
Slave address
01H
Function code 06H
Upper 00H Register
Address
Lower 01H
Upper 00H
Setting
Data
Lower 03H
Upper 98H
CRC-16
Lower 0BH
Response Message (Normal)
Slave address
01H
Function code 06H
Upper 00H Register
Address
Lower 01H
Upper 00H
Setting
Data
Lower 03H
Upper 98H
CRC-16
Lower 0BH
Response Message (Error)
Slave address
01H
80H + Function Code 86H
Error code 21H
Upper 82H
CRC-16
Lower 78H