1756-PM003H-EN-E, SFC and ST Programming Languages ...

Program Control Instructions (JSR, RET, SBR) 10-7
Arithmetic Status Flags:
Arithmetic status flags are affected.
Fault Conditions:
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 or user-supplied 0 or user-supplied
RET instruction has fewer return parameters than JSR instruction 4 31
main routine contains a RET instruction 4 31
Execution:
Relay Ladder and Structured Text
Condition: Relay Ladder Action: Structured Text Action:
prescan
The controller executes all subroutines regardless of rung condition. To ensure that all rungs in the
subroutine are prescanned, the controller ignores RET instructions. (I.e., RET instructions do not exit
the subroutine.)
• Release 6.x and earlier, input and return parameters are passed.
• Release 7.x and later, input and return parameters are not passed.
If recursive calls exist to the same subroutine, the subroutine is prescanned only the first time. If multiple
calls exist (non-recursive) to the same subroutine, the subroutine is prescanned each time.
The rung-condition-out is set to false (relay ladder only).
rung-condition-in is false to
the JSR instruction
rung-condition-in is true
The subroutine does not execute.
Outputs in the subroutine remain in their last state.
The rung-condition-out is set to false.
The instruction executes.
The rung-condition-out is set to true.
EnableIn is set na EnableIn is always set.
The instruction executes.
na
na
Publication 1756-PM003H-EN-E (excerpt from 1756-RM003H-EN-P) - August 2005