Use of the SYSTEM_b1LoopCyclicTask system variable (elimination)

Which products are affected?
EVS93xx-EI (Servo PLC Version 6.3 DSMC control board)
EVS93xx-ET (Servo PLC Version 6.3 DSMC control board)
EPL-10200-EI (Drive PLC Version 6.3)

Eliminated function restriction:
The SYSTEM_b1LoopCyclicTask system variable is set to TRUE in the first cycle of the cyclic task (PLC_PRG).

Which products are affected?
EVS93xx-EI (Servo PLC Version 2.4)
EVS93xx-ET (Servo PLC Version 2.4)
EVS93xx-EI (Servo PLC Version 6.2 DSMC control board)
EVS93xx-ET (Servo PLC Version 6.2 DSMC control board)
EPL-10200 (Drive PLC Version 6.2)

What happens?
The system variable SYSTEM_b1LoopCyclicTask is not set to TRUE. This system variable is set to the status TRUE in the first cycle of the cyclic task. This variable can be used for initialisations.

When does the problem occur?
If the system variable SYSTEM_b1LoopCyclicTask is used in a cyclic task or in another task (time-controlled task).

Possible diagnostics?
If the system variable SYSTEM_b1LoopCyclicTask and the above-mentioned operating system version are applied, more detailed diagnostics are not required.

Short-term measures/recommendations?
The three possible remedial measures are listed below:

The variable declaration can be used to initialise variables with a certain value.
The system POU PLC_ColdStart can be used to carry out initialisations. This POU will be activated if the PLC is started after a program download or a reset.
The following program (created in ST (structured text)) provides the same features as the system variable SYSTEM_b1LoopCyclicTask:

Variable g_bSYSTEM_b1LoopCyclicTask is declared globally.

(*Declaration*)
g_bSYSTEM_b1LoopCyclicTask:BOOL:=TRUE; (*FirstLoop flag*)

(*insert program part at the end of PLC PRG:*)
IF g_bSYSTEM_b1LoopCyclicTask THEN
g_bSYSTEM_b1LoopCyclicTask:=FALSE;
END_IF

(*poll g_bSYSTEM_b1LoopCyclicTask instead of SYSTEM_b1LoopCyclicTask*)

Evaluation:
When using the system variable SYSTEM_b1LoopCyclicTask two cases have to be differentiated:

Program generation / commissioning: In this case the described measures/recommendations can be applied, so that the initialisation of the system is effected correctly.
Device exchange: Use of the current operating system (e.g. 2.5 or 6.3).

If the system variable SYSTEM_b1LoopCyclicTask is not applied in the DDS project, an update of the operating system or a modification of the DDS project are not necessary.

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