YASKAWA GPD 506/P5 - Message Functions

6-2 The Message Format
Message Functions
In communicating to the GPD 506 drive via Modbus RTU, there are three message functions
available. The master specifies the function to be executed by the slave according to the function
code. The following table shows the types of function codes available, and the length (quantity) and
contents of the message according to the function.
Function
Code (hex)
Function
Command
Message
Response Message
(Normal)
min.
(bytes)
max.
(bytes)
min.
(bytes)
max.
(bytes)
03h Read Multiple Registers 8 8 7 21
08h Loop-back test 8 8 8 8
10h Write Multiple Registers 11 25 8 8
The message format varies depending upon the function of the message. For each function, there
is a command message from the master and a response message initiated from the slave. The
following sections review the format of the command message and the response message for each
function.