C.7 Message Format
YASKAWA ELECTRIC
SIEP C710636 02B YASKAWA U1000 Technical Manual 567
MEMOBUS/Modbus
Communications
C
C.7 Message Format
◆ Message Content
In MEMOBUS/Modbus communications, the master sends commands to the slave, and the slave responds. The message
format is configured for both sending and receiving as shown below, and the length of data packets depends on the
command (function) content.
◆ Slave Address
The slave address in the message defines the note the message is sent to. Use addresses between 0 and FF (hex). If a
message with slave address 0 is sent (broadcast), the command from the master will be received by all slaves. The slaves
do not provide a response to a broadcast type message.
◆ Function Code
The three types of function codes are shown in the table below.
◆ Data
Configure consecutive data by combining the MEMOBUS/Modbus register address (test code in case of a loopback test)
and the data the register contains. The data length changes depending on the command details.
A drive MEMOBUS/Modbus register always has a data length of two bytes. Therefore data written into drive registers
must also always have a length of two bytes. Register data read out from the drive will always consist of two bytes.
Function
Code
Function Name
Data Length (bytes)
Command Message Response Message
Minimum Maximum Minimum Maximum
03H Read MEMOBUS/Modbus registers 8 8 7 37
08H Loopback test 8888
10H Write to multiple MEMOBUS/Modbus registers 11 41 8 8
SLAVE ADDRESS
FUNCTION CODE
DATA
ERROR CHECK
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