4. CONTROL OF VIX DRIVES 55
Upon receipt of a valid numeric input pattern the controller runs the associated routine. For
example, binary pattern 3 causes routine L3 to run. This routine must finish (reach the END
command) before the inputs can be automatically scanned again. The state of the inputs is
presented to the controller as a parallel bit pattern. Invalid binary patterns (for non-existent
labels) are ignored.
When using the label selection function you must be aware that altering any basic operating
parameters, such as velocity, in a routine will change the value used in subsequent routines.
Consequently, you will need to define fully the move required in each subroutine block. This
can be arranged by the USE command.
System Variables
System variables are named variables held within the drive’s controller that are used for
storing a variety of system values and settings. Read system variables using the Report
system parameter (R command), but note, you can only write to certain variables using the
Write (W command).
Certain system variable values may be tested using the IF command. This allows
conditional branching within the program code, enabling equal to, not equal to, greater than
or less than decisions to be made. Wait for trigger (TR command) can also test certain
system variables by delaying code execution until the value of a system variable matches
some stored number or string within the program. Refer to the later section on conditional
code.