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10-15

10 CPU Unit Functions

CJ2 CPU Unit Software User’s Manual

10-2 Cycle Time/High-speed

Processing

10-2-5 Background Execution

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.

z 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

Cycle time

Background execution

I/O refresh

Instruction

executed

Cycle time

Omron CJ2 CPU UNIT SOFTWARE User Manual

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