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WPMZ Series Modbus communication instruction manual
IM-0862-02
Number of pages:109
9
3.
Modbus communication specification
Modbus is a single master / multislave system.
A message is sent from one Modbus master to the slave (module). The message is sent to the specified slave
(module).
3-1.
Communication procedure
When the master sends a command message, the slave (module) sends a response message to the
contents of the message.
The operations of the master side message and the slave side message are as follows.
3-2.
Transmission Switching Time
In communication between master and slave, idle time for 3.5 characters is required for transmission /
reception switching.
Please refer to the table below for the idle time for 3.5 characters.
In the WPMZ-5/6 series, the communication speed and parity setting can be changed.
Table 3.1 3.5 character idle time (reference value)
communication
speed
With parity
(Even number, odd
number)
No parity
9600bps
4.01ms
3.65ms
19200bps
2.01ms
1.82ms
38400bps
1.00ms
0.91ms
Master
Slave
(module)
Command
message
Response
message
Command
message
Response
message
Figure 3.1 Communication procedure
Master
side
message
transmission
Slave side message
response
Idle
t
ime
Idle
t
ime