Manual

3-40 Detailed Descriptions of ACL Commands
Note that it is possible to execute moves whose total length exceeds 65535 microsteps. In
this case the middle portion of the move will be unreachable by the MM command; the
Digital Outputs will not change in this region. If the length is in the range 32768 through
65535, a portion near the end will be unreachable by positive <count> values and
vice-versa.
The parameters <new> and <which> determine the new values written to the Digital
Outputs. Each of these parameters is optional, and may only be specified if all preceding
parameters have been specified. In any given MM command if <count> is specified, <new>
must also be specified.
<new> is modified by <which> and is output at <count>. For more information about the
range and meaning of these parameters, see the <new> and <which> parameters of the CD
command.
If <which> is omitted it defaults to 255 (i.e. binary 11111111), meaning that all 8 Digital
Outputs are affected by the corresponding <new>.
After power up and IN, and if an MM or MD with no parameters is executed, mid-move
Digital Outputs changes are disabled.
The MM command does not use the delay specified by the WD command. The values of
each <count> must be coordinated with current acceleration and step rate such that any
hardware attached to the Digital Outputs has enough time to actuate. If you need a precise
delay between the first change and the beginning of motion, use the PD (“Pre-move Digital
Outputs Changes”) command.
Unusual Conditions
Each MM command's <count> value, whether positive or negative, resolves to a particular
distance from the beginning of a given move. If more than one <count> resolves to the
same microstep position within a given move, the next <new> value is output approximately
135 microseconds after the preceding <new> value.
If any <count>'s distance is less than that of the immediately preceding MM's <count>, the
following action is taken: the average of the two distances is computed, and both Digital
Outputs changes are performed at this intermediate distance, although separated by
approximately 135 microseconds.
The MM's will be output in the same order that they were originally specified, even though
their <count> values may be out of order. Each MM becomes a candidate for output as soon
as the move has gone the specified distance, but will not be output until all
previously-specified MM's are output. All specified MM's will be output during each move.
(For an exception with MN, see below).
A zero-length move (for example, due to MR 0,0; two MA's to the same location, or an arc
with zero radius or sweep angle) produces all Digital Outputs changes specified, each one
separated by approximately 20 microseconds from the preceding one.
A move which has a non zero length that is less than any or all of the MM <counts> will
cause all unprocessed MM's to be output at the end of the move, separated by approximately
20 microseconds.