84
CPU Unit Operation Section 2-4
Note CJ-series Special I/O Unit, CJ-series CPU Bus Unit, USB port, serial port,
and communications port servicing is allocated 4% of the previous cycle time
by default (the default can be changed) for each service. If servicing is sepa-
rated over many cycles, delaying completion of the servicing, set the same
allocated time (same time for all services) rather than a percentage under
execute time settings in the PLC Setup.
2-4-3 I/O Refresh Methods
I/O for CPU Unit built-in I/O and I/O on CP-series Expansion Units and Expan-
sion I/O Units is performed at the following times.
1,2,3... 1. Cyclic refresh period
2. When instructions with an immediate refresh variation are executed
3. When IORF(097) is executed
Cyclic Refreshing I/O is refreshed after all the instructions in executable tasks have been exe-
cuted.
Communications port servic-
ing
• Servicing to execute network communications or
serial communications for the SEND, RECV, CMND
or PMCR instructions using communications ports
0 to 7 (internal logical ports)
• Servicing to execute background execution using
communications ports 0 to 7 (internal logical ports)
Built-in flash memory access
servicing
• Read/write processing for built-in flash memory
Memory Cassette access ser-
vicing
• Read/write processing for a Memory Cassette
Service Description
END(001)
END(001)
END(001)
Task
Task
Task
I/O refresh period
Cycle
I/O terminal
status
To Next Page
Loading...
Need help?
General
