Data Communications Between Target Devices And Cpu Module By Designating A Master Station And Slave Stations - Mitsubishi Electric MELSEC iQ-R Series User Manual

Data communications between target devices and CPU module
by designating a master station and slave stations
One of the target devices becomes the master station and the other target devices communicate data with the CPU module
after obtaining permission from the master station.
Ex.
Master station
target device
Communications
Communications
complete report
request
Slave station
target device 1
Slave station
target device 2
Slave station
target device m-1
The example below shows the procedures for each target device to communicate data with the CPU module.
In this example, after the start of data communications between a target device and the CPU module, each device checks for
timeout of the maximum data communication time. In addition, devices on the slave station, which are not communicating
data with the CPU module, check if the target device that completed data communications with the CPU module transmitted a
communication complete report.
In the following descriptions, the target device with the lowest station number(1BH) is the master station and the other target
devices are slave stations.
Ex.
(Before Ó)
Master station
Target device
(Station No.:1BH)
Ó
(Station No.:0H)
CPU C24
 A slave station that wants to communicate data with the CPU module sends a communications request to the master
station to obtain the line ownership. A message structure example is shown in .
18 DATA COMMUNICATIONS BETWEEN TARGET DEVICE AND CPU MODULE IN M:N BASIS
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18.3 Examples of Procedure for Data Communications with CPU Module
Permission
granted
response
Communications
request
Respo
Permission
nse
granted
response
Data
communications
with CPU module
(after Ó)
Target device
(Station No.:1CH)
Ò
(Station No.:1H)
CPU C24
Time
General report to
Communications
start and end data
communications request
between master
station and
CPU module
Permission
granted
response
Start End
Target device
(Station No.:1DH)
(Station No.:2H)
CPU C24
The above C24 includes Q series C24, L series C24, QC24(N), and UC24.
Communications
complete report
Response
Data Data
communications communications
with CPU module with CPU module
Target device
(Station No.:1EH)
(Station No.:15H)
CPU C24
Target device that obtained the line ownership