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264
Programming Appendix A
Subroutines
What Are Subroutines?
A subroutine is a program written between the SBN(092) and RET(093) instructions in a special subroutine
area. A subroutine is called from the main program using the SBS(091), MCRO(099), or JSB(982) instruction.
Subroutines can be used in the following three ways with the FQM1.
Using Normal Subroutines
A normal subroutine is written between the SBN(092) and RET(093) instructions and called using the
SBS(091) instruction.
1. Write the program to be executed between SBN(092) and RET(093).
2. Set the subroutine number for the operand of SBN(092).
3. Call the subroutine using SBS(091)
Type of subroutine Description Calling instruction
Normal subroutines Normal subroutines are executed without passing parameters. SBS(091)
Subroutines for
which parameters
are passed
• Parameters can be passed to the subroutine.
• The results of processing in the subroutine can be returned to the
main program.
MCRO(099)
• Flags can be used to access the input condition to the subroutine
while the subroutine is being executed.
• It’s possible to check to see if a subroutine has been executed in the
past.
• Parameters can be passed to and from the subroutine using storage
registers.
JSB(982)
SBN
100
RET
SBS
100
SBN
10
RET
Set the subroutine
number to call. Here,
the subroutine number
is 100.
Main program
(section 1)
Subroutine
(section 2)
Set the the subroutine
number. Here, the
subroutine number is
100.
Subroutine
(section 3)
Set the the subroutine
number. Here, the
subroutine number is
10.
Processing
Processing