Manual

Detailed Descriptions of ACL Commands 3-43
The <value> and <which> parameters set up a Digital Inputs condition which is to trigger
the automatic actions. The parameters are treated as 8-bit numbers and are similar to the
<new> and <which> parameters of the CD command, respectively. That is, the System
checks that each Digital Input matches the corresponding bit of <value>, where a True input
matches a 1 bit and a False input matches a 0. However, the System only checks those
Digital Inputs which correspond to a 1 bit in <which>. All other Digital Inputs are ignored
and do not need to match.
The <which> parameter is optional but may only be specified if <mode> and <value> are
also specified. If <which> is omitted it defaults to 255 (i.e. binary 11111111), meaning that
all eight Digital Inputs must match <value>.
If the specified Digital Inputs condition already exists when a move command is executed
then the System performs the automatic action before any motion occurs. If the Dynamic
Deceleration feature is enabled then the command produces no motion.
Only the first occurrence of the <value>/<which> condition during any given move
produces an automatic action. Subsequent occurrences during the remainder of that move
are ignored, unless they persist until the next move, at which time they will be seen.
During a vector the Digital Inputs are tested approximately once every 135 microseconds
(0.000135 second); during an arc or Continuous Path move, approximately once every 450
microseconds (0.000450 second); and during a Z move, approximately once every 100
microseconds (0.000100 second). You must ensure that the desired Digital Inputs condition
lasts for at least, say, one millisecond (0.001 second) so that the Automove System will not
miss it.
A zero-length move (for example, MR 0,0; ) checks the Digital Inputs once. Therefore you
can use MN to "teach" the present position, via the following sequence: MN 1,0,0; MR
0,0; MN; . The first MN has a zero <which> so that the MR "teaches" immediately
regardless of the state of the Digital Inputs. This could be useful, for example, to
"memorize" and later return (via MT) to a position that resulted from a complicated series of
motions or an operator input via the Arrow buttons.
The automatic actions of MN do not take place during antibacklash vectors (see the AB
command), during the Find Home motion, or during any front-panel motion such as GO TO
ORIGIN or Arrow buttons. The Digital Inputs are ignored during these moves.
Note: after an XY Dynamic Deceleration the commanded position will be at the expected
endpoint but the actual position will be wherever the carriage actually came to rest in the
middle of the move. If you then execute an AA, AR, or MR the System will "think" it is at
the commanded position and may behave in an unexpected way. (For example, an MR 0,0;
will go to where the original move would have gone, had there been no Dynamic
Deceleration.) It may be useful to perform an MT ("Move To Taught Point") before doing
an AA, AR, or MR.
Note that no signal debouncing of the Digital Inputs is performed in conjunction with MN.
(For more information about debouncing please see Chapter 8). Normally this will not cause
any problems because only one response can occur during a given move. By the time the
move finishes and another move starts any switch bounce will probably be over. However,
if your switches are switching near the end of an already-decelerating move (or if high
acceleration produces an extremely short deceleration phase) then you may need to insert a
short delay between moves; see the WA command.