Jump to Subroutine (JSR), Subroutine (SBR), and Return (RET)

JSR(RoutineName,InputCount,InputPar,ReturnPar);

SBR(InputPar);

RET(ReturnPar);

IMPORTANT

Unexpected operation may occur if: Output tag operands are overwritten. Members of a structure operand are overwritten. Except when specified, structure operands are shared by multiple instructions.

Operand	Data Type	Format	Description
Routine Name	ROUTINE	name	Subroutine to execute
Input Par	BOOL SINT INT DINT LINT USINT UINT UDINT ULINT REAL LREAL structure	immediate tag array tag	Data from this routine to copy to a tag in the subroutine. Input parameters are optional Enter a maximum of 40 input parameters, if needed.
Return Par	BOOL SINT INT DINT LINT USINT UINT UDINT ULINT REAL LREAL structure	tag array tag	Tag in this routine to copy result from subroutine. Return parameters are optional Enter a maximum of 40 return parameters, if needed

Operand	Data Type	Format	Description
Input Par	BOOL SINT INT DINT LINT USINT UINT UDINT ULINT REAL LREAL structure	tag array tag	Tag in this routine into which to copy the corresponding input parameter (maximum 40) from the JSR instruction.

Operand	Data Type	Format	Description
Return Par	BOOL SINT INT DINT LINT USINT UINT UDINT ULINT REAL LREAL structure	immediate tag array tag	Data from this routine to copy to the corresponding return parameter (maximum 40) in the JSR instruction.

A major fault will occur if:	Fault type	Fault code
JSR instruction has fewer input parameters than SBR instruction	4	31
JSR instruction jumps to a fault routine	4	990 or user-supplied
RET instruction has fewer return parameters than JSR instruction	4	31
Main routine contains a RET instruction	4	31

IMPORTANT

Any routine may contain a JSR instruction but a JSR instruction cannot call (execute) the main routine.

The subroutine executes each time it is scanned.
After the subroutine executes, logic execution returns to the routine that contains the JSR instruction and continues with the instruction following the JSR.

To copy data to a tag in the subroutine enter an input parameter.
To copy a result of the subroutine to a tag in this routine, enter a return parameter.
Enter up to 40 inputs and enter up to 40 return parameters as needed.

If the JSR instruction has an input parameter enter an SBR instruction.
Place SBR instruction as the first instruction in the routine.
For each input Parameter in the JSR Instruction, enter the tag into which you want to copy the data.

If the JSR instruction has a return parameter, enter an RET instruction.
Place the RET instruction as the last instruction in the routine.
For each return parameter in the JSR instruction, enter a return parameter to send to the JSR instruction.
In a ladder routine, place additional RET instructions to exit the subroutine based on different input conditions, if required (Function block routines only permit one RET instruction).

Tip: Select the Edit > Edit Ladder Element menu to add and remove variable operands. For the JSR and SBR instructions, add Input Parameter. For JSR and RET instructions, add Output Parameter. For all three instructions, remove Instruction Parameter.

Condition/State	Action Taken
Prescan	The rung is set to false. The controller executes all subroutines. To ensure that all rungs in the subroutine are prescanned, the controller ignores RET instructions (that is, RET instructions do not exit the subroutine). Input and return parameters are not passed. If the same subroutine is invoked multiple times, it will only be prescanned once.
Rung-condition-in is false (to the JSR instruction)	N/A
Rung-condition-in is true	Parameters are passed and the subroutine is executed.
Postscan	Same action as Prescan