The axis object cannot be used after being put into an array?

Question

Codesys v3.5 sp20+(32bit)

I hope to power up the specified axis through the following code,It worked.

The following code is called cyclically,It's called by a task every 4 milliseconds.

PROGRAM PowerupTest
VAR
    MC_Power_0: MC_Power;
    Axises:ARRAY[0..5] OF SM3_Drive_ETC_DS402_CyclicSync.AXIS_REF_ETC_DS402_CS;
END_VAR

MC_Power_0(
    Axis:=Axis0, 
    Enable:=1 , 
    bRegulatorOn:=1 , 
    bDriveStart:=1 , 
    Status=> ,
    bRegulatorRealState=> , 
    bDriveStartRealState=> , 
    Busy=> , 
    Error=> , 
    ErrorID=> 
);

Now, to change it a little bit, I save Axis0 into an array first, and then pass the elements of the array into the MC_Power function block.
It doesn't work properly anymore.

Axises[0]:=Axis0;

MC_Power_0(
    Axis:=Axises[0],   //Changed here
    Enable:=1 , 
    bRegulatorOn:=1 , 
    bDriveStart:=1 , 
    Status=> ,
    bRegulatorRealState=> , 
    bDriveStartRealState=> , 
    Busy=> , 
    Error=> , 
    ErrorID=> 
);

Could you tell me the possible reason? I hope I can access all axes as an array.

Thank you.

=========================

I made the following changes, but it still doesn't work.

PROGRAM PowerupTest
VAR
    MC_Power_0: MC_Power;
    Axises:ARRAY[0..5] OF SM3_Drive_ETC_DS402_CyclicSync.AXIS_REF_ETC_DS402_CS;
    IsInitialized:BOOL:=false;
END_VAR

IF NOT IsInitialized THEN
    Axises[0]:=Axis0;
    IsInitialized:=TRUE;
    RETURN;
END_IF



MC_Power_0(
    Axis:=Axises[0], 
    Enable:=1 , 
    bRegulatorOn:=1 , 
    bDriveStart:=1 , 
    Status=> ,
    bRegulatorRealState=> , 
    bDriveStartRealState=> , 
    Busy=> , 
    Error=> GVL.LastError, 
    ErrorID=> GVL.LastErrorId
);

Answer 1

Problem solved, I should use a pointer to save the reference to the axis object

PROGRAM PowerupTest
VAR
    MC_Power_0: MC_Power;
    Axises:ARRAY[0..5] OF POINTER TO SM3_Drive_ETC_DS402_CyclicSync.AXIS_REF_ETC_DS402_CS;
    IsInitialized:BOOL:=false;
END_VAR

Axises[0]:=ADR(Axis0);

MC_Power_0(
    Axis:=Axises[0]^, 
    Enable:=1 , 
    bRegulatorOn:=1 , 
    bDriveStart:=1 , 
    Status=> ,
    bRegulatorRealState=> , 
    bDriveStartRealState=> , 
    Busy=> , 
    Error=> , 
    ErrorID=> 
);

Answer 2

I assume the code shown is called cyclically.

Then, it seems likely to me that the problem is that you overwrite Axis[0] with the content of Axis0 every cycle. Since Axis0 is not used, its internal state never changes, so anything that was done to Axis[0] as part of the call to MC_Power_0 is wiped out.

Why to you have Axises[0]:=Axis0;? If there is some initialization done to Axis0 that you want to transfer to Axis[0], you can do the same directly with Axis[0] instead. If you really want to keep this line, make sure it is called only once at the beginning of your program rather than at every cycle.