====== On LadderInt ======

''On LadderInt GoSub label''

If Register F40 turns on in Ladder Logic, and the ''On LadderInt GoSub''
command is used, then the processor will jump to the routine (''label'')
specified by ''On LadderInt''.

This can be used when a Ladder Logic program needs to trigger a specific
procedure in BASIC.

Please use the ''SETOUT'' and ''DF'' command to write 1 to the register F40.
When the BASIC interrupt routine is finished, register F40 can be cleared by
writing a zero to it.

During the interrupt service routine(ISR) execution, writing a 1 to register
F40 will not allow another interrupt to occur. If register F40 is cleared from
BASIC, it signals the end of the ISR and can process another interrupt.

<code xbasic>
  UsePin 0,In
  Set Ladder On
  Set Display 0,0,16,77,50
  On LadderInt GoSub msg1_rtn
  Dim i As Integer
  Low 1
  Do
    i=i+1
    ByteOut 1,i
    Delay 200
  Loop
  
msg1_rtn:
  Locate 0,0
  Print "ON LadderInt",Dec i
  Reverse 1
  Return
</code>

{{ :cubloc:on_ladderint:onladderint.png?nolink |}}

When P0 turns on, register F40 turns on and the ''msg1_rtn'' interrupt routine
in BASIC is executed. In the ISR, a String is printed to the LCD.

Although there is only one register, F40, with which call an ISR in BASIC
from Ladder Logic, we can use data register D to process many different
types of interrupts.

{{ :cubloc:on_ladderint:onladderint2.png?nolink |}}

Given the ladder above, when P0 turns on, D0 gets 3 and the interrupt
routine is executed. If P2 turns on, D0 gets 2 and the interrupt routine is
executed. In the ISR, the user can then process the type of interrupt based
on the value stored in D0.

<code xbasic>
msg1_rtn:
  If _D(0)=3 Then
    Locate 0,0
    Print "ON Ladderint",Dec i
  End If
  If _D(0)=2 Then
    Locate 0,0
    Print "TEST PROGRAM",Dec i
  End If
  Return
</code>

For a short version of the ladder above the user can use an ''INTON''
command, which accomplishes both ''WMOV'' and ''SETOUT'' in one command.

The following is an equivalent shortened version of the ladder above:

{{ :cubloc:on_ladderint:onladderint3.png?nolink |}}


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