Manual

Detailed Descriptions of ACL Commands 3-37
Each Digital Output can only have one value at a time, either True or False (one or zero).
The CD and TD commands change the outputs immediately; the MD and MM commands
causes the outputs to change later, when vectors or arcs are performed. Once an output has
been changed either by a CD or TD or by a move after a PD, MD, or MM, the old value of
that output is forgotten.
If the value of <count1> or <count2> is positive, it specifies the number of microsteps
from the beginning of the move, at which the Digital Outputs are to change state. If
negative, it specifies the distance before the end of the move. The range of <count1> and
<count2> is -32768 through 32767. Zero is interpreted as the beginning of the move,
before the first step is taken.
If the magnitude of <count1> or <count2> is bigger than the length of a particular move,
the Digital Outputs will change at the beginning or end of the move, as appropriate. If a
vector is diagonal the true diagonal distance, in microsteps, is used.
<count1> and <count2> are applied to an AA or AR arc or Continuous Path move as
though the move were "unrolled" into a straight line. In other words, a positive number is an
arc-length distance from the beginning of the move, and a negative number is a distance
from the end. (See the BC command.)
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 MD 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 <new1>, <new2>, <which1>, and <which2> 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. If a <count> is specified, the
corresponding <new> must be specified.
<new1> is modified by <which1> and is output at <count1>. <new2> is modified by
<which2> and is output at <count2>. For more information about these parameters, see the
<new> and <which> parameters of the CD command.
If a <which> is omitted it defaults to 255 (i.e. binary 11111111), meaning that all 8 Digital
Outputs are affected by the corresponding <new>.
If <count2>, <new2>, and <which2> are omitted, the Digital Outputs will change only
once during each move. <count2> and <new2> may be specified only if <count1>,
<new1>, and <which1> are all specified.
After power up and IN, and if an MD or MM with no parameters is executed, mid-move
Digital Outputs changes are disabled.
The MD command does not use the delay specified by the WD command. The values of
<count1> and <count2> 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.