Manual

Detailed Descriptions of ACL Commands 3-11
Digital Inputs And Outputs
The entire Continuous Path sequence is treated as though it were a single vector or arc, for
the purposes of the following commands: MD, MM, MN, PD, and VM.
For example, suppose an MD command has set up a Digital Outputs change which is to
occur 1000 microsteps after the beginning of the move, plus another which is to occur 200
microsteps before the end. (The command might be: MD 1000, 2, 2, -200, 0, 2;.) The
Digital Outputs will change 1000 steps after the beginning of the BC...EC sequence, no
matter how many vectors or arcs have already been executed. Then the Outputs change
again, 200 steps from the end of the entire sequence. It is as though the Continuous Path
sequence were "unrolled" into a straight line.
The CD and TD commands are executed wherever they appear within the BC...EC
sequence. For example, the sequence:
BC; MR 100,0; CD 255; MR 100,0; EC;
produces a move of 200 microsteps to the right. Exactly in the middle of the move, all of the
Digital Outputs are turned on.
If a given Continuous Path sequence is executed with MD or MM active and it also contains
CD or TD commands, both kinds of Digital Outputs changes occur as specified.
Interrupts and Front Panel
For the purposes of interrupts caused by the Digital Inputs, the entire BC...EC sequence is
treated as a single move. In other words, no interrupt can occur from when the BC is
executed until after the Continuous Path motion is complete. See Chapter 8 Using the
Digital Outputs and Inputs.
Once the EC has executed and motion has begun, no front panel button except STOP,
RESET, or PAUSE will be acted upon until the BC...EC sequence is complete. The PAUSE
button is "remembered" and the machine pauses upon completing the Continuous Path
move. STOP and RESET occur immediately.
If any front panel XY motion occurs between BC and EC (due to the Arrow buttons or GO
TO ORIGIN) an error is logged and no Continuous Path motion is performed.
Delays, Emergency Stop, Antibacklash, Host Interrogation
As the physical action commands are processed there is a delay before motion begins. The
amount of delay depends on how many vectors and arcs are contained in the sequence; the
delay is about 28 seconds for 200 downloaded, rotated MA vectors and about 16 seconds for
200 downloaded AA arcs. (If MR or AR is used, or if the commands are being sent from the
host, the delay will be even longer.) This delay can be eliminated if the same Continuous
Path sequence is to be repeated; see "Repeating The Sequence", above.