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DeviceNet Connections Appendix B
Master COS Send Switch
COS transmission is possible only for User-set allocations using the Configurator.
When required, remote I/O output data can be output from the master to a specified slave.
Output data can be sent at the communications cycle timing to the specified slave by other connections
selected automatically or by the user (only when using the Configurator).
In this case, the communications timing is not dependant on the communications cycle time but it is dependant
on the CPU Unit cycle time.
Note When there are a lot of masters or slaves using COS communications, or when the number of transmis-
sions using COS is high, it has a large impact on the remote I/O communications performance for each
normal communications cycle time and responses may be delayed. Therefore, give ample consideration
to the system performance when using COS.
DeviceNet Units use the Master COS Send Switch in the allocated CIO Area words to execute COS transmis-
sions from the master to slaves. The procedure is outlined below.
Step 1
Before executing COS transmission, the connection for the destination slave must be set to COS in the master
scan list, using the Configurator.
Step 2
If the bit allocated to each node address from n + 2 words to n + 5 words is turned from OFF to ON, the output
data is sent to that node address at a timing independent of the communications cycle time.
Multiple bits can be turned OFF to ON simultaneously and output data can be sent to multiple node addresses
simultaneously.
CPU Unit user program
DeviceNet Unit
Slave
COS send switch OFF to ON
I/O refresh Time
COS send instruction
I/O using normal connection
COS output
Communications
cycle time
Communications
cycle time
Communications
cycle time
Communications
cycle time