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5 Network Communications
The timer within the master must be set to check how long it takes for the slave to respond to the master. If the
timer is set and a response message is not returned back from the slave within a certain amount of time, the master
retransmits the message.
Response Message from Slave
When the slave receives the command message from the master, it processes the data that was sent. When the wait
time set in H5-06 [Drive Transmit Wait Time] passes, it sends a response message to the master. Increase the wait
time set in H5-06 when overrun occurs on the master.
■
Message Format
Communication Message Description
In MEMOBUS/Modbus communications, the master sends commands to the slave, then the slave responds. The
master and slave send their messages in the configuration in Figure 5.7. The length of the data changes when the
description of the command (function) changes.
Slave Address
Set the slave address of the drive to 00 to FF (Hex.). When the slave address is 00 (Hex), the master sends the
command and all slaves receive the command.
The slave will not send a response message to the master.
Function Code
There are five function codes that set commands. Table 5.4 shows the different codes.
Subfunction
Function Code
Code
(Hex.)
(Hex.)
03
-
08
-
10
-
5A
-
288
Figure 5.6 Response Wait Time
Figure 5.7 Message Format
Table 5.4 Function Codes
Command Message
Minimum Data
Function
Length
(byte)
Read the
Description of
8
Holding Register
Loopback Test
8
Writing to
Multiple Holding
11
Registers
Writing to
Multiple Holding
Registers /
11
Reading the
Register Indicated
YASKAWA ELECTRIC SIEP C710617 19A YASKAWA AC Drive CR700 Technical Manual
Response Message
Maximum Data
Minimum Data
Length
Length
(byte)
(byte)
8
7
8
8
41
8
41
17
Maximum Data
Length
(byte)
37
8
8
17
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