Omron CJ2 CPU UNIT SOFTWARE User Manual page 349

Additional Information
The internal logical ports in the CPU Unit are used both for background execution and the follow-
ing instructions:
• SEND(090), RECV(098), and CMND(490) (Network Instructions)
• PMCR(260) (PROTOCOL MACRO)
• TXDU(256) and RXDU(255) (the no-protocol communications instructions used with Serial
Communications Units)
Background instructions and the above instructions cannot be executed simultaneously on the
same port. Use the Communications Port Enabled Flags to be sure that only one instruction is
executed on each port at any one time.
Note If an instruction is specified for execution in the background for a port for which the Communications Port
Enabled Flag is OFF, the ER Flag will turn ON and the background instruction will not be executed.
Communications Port Enabled Flags
The Communications Port Enabled Flags are ON when the port is not being used and OFF when
processing is being performed on the port.
Communications Port Enabled Flag
Background instruction processing
for user program
CJ2 CPU Unit Software User's Manual
1
0
Instruction
executed
Cycle time
Cycle time
Background execution
10 CPU Unit Functions
Cycle time
I/O refresh
10
10-15