86
CPU Unit Operation Section 2-4
Note (1) 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 ser-
vicing is separated over many cycles, delaying completion of the servic-
ing, set the same allocated time (same time for all services) rather than a
percentage under execute time settings in the PLC Setup.
(2) An error will be occurred if the cycle time is too long.
Modify the CX-Programmer’s response monitoring time longer according
to the following method.
Start the CX-Programmer. Select Change Model from the PLC Menu.
The Change PLC Dialog Box will be displayed. Click the Settings Button
on the right side of Network Type. The Network Settings [USB] Dialog
Box will be displayed. Click the Network Tab and increase the value in
Response Timeout(s).
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