User guide

88 6250 Servo Controller User Guide
Unconditional
Branching
There are three ways to branch unconditionally:
❏ GOSUB: The GOSUB command branches to the program name or label stated in the GOSUB
command. After the subroutine is completed, control is returned to the calling program where
the branch occurred, starting with the line after the GOSUB.
❏
GOTO: The GOTO command transfers control from the current program being processed to the
program name or label stated in the GOTO command. Unlike the GOSUB, the program or label
that the GOTO initiates will not return control to the calling program—instead, the program
will end. This holds true unless the subroutine in which the GOTO resides was called by another
program; in which case, the END in the GOTO program will initiate a return to the calling
program.
❏
JUMP: The JUMP command branches to the program name or label stated in the JUMP command.
All nested IFs, WHILEs, and REPEATs, loops, and subroutines are cleared; thus, the program or
label that the JUMP initiates will not return control to the line after the JUMP, when the
program completes operation. Instead, the program will end.
If an invalid program or label name is entered, the branch command will be ignored and
processing will continue with the next line in the program.
NOTE
Be careful about performing a GOTO within a loop or branch statement area (i.e., between L & LN,
between IF & NIF, between REPEAT & UNTIL, or between WHILE & NWHILE). Branching to a
different location within the same program will cause the next L, IF, REPEAT, or WHILE statement
encountered to be nested within the previous L, IF, REPEAT, or WHILE statement area, unless an
LN, NIF, UNTIL, or NWHILE command has already been encountered. If you wish to avoid this
nesting situation, use the JUMP command instead of the GOTO command.
Example
Command Description
> DEF cut1 Begin definition of program cut1
- HOM11 Send axes 1 and 2 to the home position
- WAIT(1AS=bØXXX1 AND 2AS=bØXXX1) Wait for axes 1 and 2 to come to a halt at home
- GOSUB prompt Go to subroutine program called prompt
- MAØØ Place axes 1 and 2 in the incremental mode
- A1Ø,3Ø Set acceleration: axis 1 = 10 rps
2
, axis 2 = 30 rps
2
- AD5,12 Set deceleration: axis 1 = 5 rps
2
, axis 2 = 12 rps
2
- V5,8 Set velocity: axis 1 = 5 rps, axis 2 = 8 rps
- D16ØØØ,1ØØØØØ Set distance: axis 1 = 16,000 steps,
axis 2 = 100,000 steps
- OUT.6-1 Turn on output number 6
-T5 Wait for 5 seconds
- L(VAR2) Begin loop ( the number of loops = value of VAR2)
- GO11 Initiate moves on axes 1 and 2
-T3 Wait for 3 seconds
-LN End loop
- OUT.6-Ø Turn off output number 6
- END End definition of program cut1
> DEF prompt Begin definition of program prompt
- VARS1="Enter part count >" Place message in string variable #1
- VAR2=READ1 Prompt operator with string variable #1, and read
data into numeric variable #2
- END End definition of program prompt
> RUN cut1 Run the program called cut1
After issuing the RUN cut1 command, the program cut1 is executed until it gets to the
command GOSUB prompt. From there it branches unconditionally to the subroutine (actually a
program) called prompt. The subroutine prompt queries the operator for the number of parts to
process. After the part number is entered (e.g., operator enters the !'12 command to process
12 parts), the rest of the prompt subroutine is executed and control goes back to the cut1
program and resumes program execution with the next command after the GOSUB, which is MAØØ.
Conditional Looping and Branching