What instruction is used to send program flow out to a sub program?

The instruction used to send program flow out to a subprogram is the CALL instruction. This command is specifically designed to invoke a separate subprogram when executed. It allows the main program to transition control to the subprogram, enabling it to execute a set of instructions defined within that subprogram. Once the subprogram completes its execution, control returns to the point in the main program right after the CALL instruction.

Utilizing CALL is essential for structuring complex robotic tasks, as it enables modular programming, where sections of code can be reused across different parts of a program or even across different programs. This not only enhances readability but also simplifies maintenance and troubleshooting by isolating functionality into discrete units.

In contrast, other options do not fulfill this purpose. The JMP/LBL pair is typically used for jumping to a specified label within the same program, not for calling a subprogram. REMARK serves as a comment feature to include annotations in the code for clarification and documentation purposes, but does not affect program flow. SELECT is used for conditional branching and decision-making, which does not involve invoking a subprogram. Hence, CALL stands out as the appropriate choice for transferring control to a subprogram in FANUC programming.