Chapter 9 Appendix
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VFD300 series inverter has built-in the Modbus-RTU communication protocol, and is applicable
to response the slave “Inquiry/command” or doing the action according to the master’s “Inquiry /
Command” and response to the data.
Here, master is personnel computer (PC), industrial machine or programmable logical controller
(PLC), and the slave is inverter. Master not only visits some slave, but also sends the broadcast
information to all the slaves. For the single master “Inquiry/Command”, all of slaves will return a
signal that is a response; for the broadcast information provided by master, slave needs not
feedback a response to master machine.
Communication data structure
Modbus protocol communication data format of VFD300 series inverter is shown as following.
The inverter only support the reading and writing of Word type parameters, the corresponding
reading operation command is “0x03”, the writing operation command is “0x06”. The writing and
reading operation of byte or bit is not supported.
In theory, the host computer can continuously read several function codes once (that is, the
maximum value of “n” is 12), but note that not to jump across the last function code in this
function group to avoid the wrong reply.