Manual

Detailed Descriptions of ACL Commands 3-79
<id> is the identifying number, 0 through 255, of the Sequence to be repeated. <value> and
<which> specify the condition to test before each execution; see the WN command for the
meaning of these parameters. <which> is optional; it defaults to 255 if omitted, meaning
that all eight Digital Inputs are checked.
The Digital Inputs are tested before each execution of the Download Sequence. If the
condition is met the Download Sequence is executed. But if the condition is not met the
Download Sequence is not executed any more and execution resumes at the ACL command
following the XW command. Thus, the XW command might not execute the Download
Sequence at all if the condition is not met the very first time the Inputs are tested.
For information about debouncing and signal sense (High True vs. Low True) see Chapter 8
Using the Digital Outputs and Inputs.
Example: suppose you are using the Automove System to dip integrated circuit leads into a
vat of molten solder. The IC's are fetched, one at a time, from a feeder station. A
microswitch at the feeder station closes when the station is empty; i.e., when there are no
more IC's left. The microswitch is connected to Digital Input 2.
Suppose you have set up Download Sequence 16 to fetch a part, dip it in the solder, and drop
it into a bin. You do not wish to execute Sequence 16 if the feeder has emptied. You might
use XW 16, 0, 4; to process IC's as long as there are any left; i.e., as long as the
microswitch is open. If you had used the XU ("Execute Until") command ( XU 16, 1, 4; )
your system would have performed Sequence 16 once before discovering that the feeder is
empty.