Manual

3-12 Detailed Descriptions of ACL Commands
The entire BC...EC sequence is ignored if it occurs while the machine is in the Emergency
Stopped state. If the STOP button is pressed (or an external Emergency Stop switch closes)
during the motion, the motors stop immediately and the Home position reference becomes
inaccurate. See the STOP button in Chapter 4 and the FH command in this chapter.
Antibacklash vectors are temporarily disabled during a Continuous Path sequence. If they
were enabled at the time the BC was executed, they will automatically become re-enabled
after the EC.
The host computer can inquire how many physical action commands have been processed
since the BC command, and how many are allowable. See the
ESC.S6: and ESC.S7:
commands in Chapter 6.
Position Errors
As with single (non-Continuous Path) arcs, each arc may leave the carriage several
microsteps away from the "ideal" arc endpoint. These position discrepancies are cumulative
during a single Continuous Path sequence; in other words, the position error may grow
larger as more arcs are executed.
Continuous Path vectors do not increase the position error, but neither do they eliminate it.
The position error is eliminated at the first vector after the EC command. The most
straightforward way to be sure the carriage is at the "ideal" point is to execute an MR 0, 0;
after the EC. This may be unnecessary, since any subsequent vector will eliminate the
position error.
Examples
The following ACL sequence generates a "race track" -- an oval- shaped closed curve:
MA 3000, 2000; BC; MR 2000, 0; AR 0, 1000, 180;
MR -2000, 0; AR 0, -1000, 180; EC;
There are four moves between BC and EC -- two vectors (MR) and two arcs (AR). The
carriage moves to 3000, 2000 and stops; then it moves in a nonstop counterclockwise oval,
ending up where it started.
The following example shows how Continuous Path can be used to produce a move of great
length. Suppose your application uses a leadscrew table and, for high endpoint resolution,
you are using high microstep factors (via RE 32, 32; ). Normally, the overall travel limit
of the Automove System is 32766 microsteps in each axis. Suppose, however, that you need
to move 80000 microsteps from the Home switches in order to reach the "active area" of
your application. The following sequence finds the Home switches and then moves 80000
microsteps away in each axis, in a single move:
FH; SO 0, 0; CF 1, 1; BC; MA 30000, 30000; SP 0, 0;
MA 30000, 30000; SP 0, 0; MA 20000, 20000; EC;