External addresses used in the logic program (connection device) are target addresses updated at the defined frequency. Other addresses that are not used in the logic program are not part of the target address list.
External addresses for which communication scanning has stopped are not targets either.
They are processed only when the power is ON or controller is reset.
The effect is different from typical processes, depending on the speed of address refreshing.
For communication checking after running a logic program, monitor the L system variable " #L_RefreshEnable" in the logic program.
If a communication error occurs when the power is ON, not even the logic program will run.
A connection device that stopped communication scanning retains its status before stopping the scanning.
If [External Equipment Operations] is [Synchronous], the logic will not operate until communication synchronization with the external device is checked.
If [External Equipment Operations] is [Synchronous], communication synchronization is checked even when [Logic Program Operation] is [STOP].
In a Logic Program, when Backup Internal Device is set up, do not enable internal addresses. When powering up the display unit, restoring backup data from SRAM to internal addresses is not synchronized with starting the logic program. As a result, the logic program could load and run before backup data is restored.
When you want to back up data used in the logic program, set up retentive variables.
29.3.2.4 Retentive Variable Settings