Technical Reference
Motion Programming
6
www.galilmc.com / Galil Motion Control, Inc.
The generation of more complex moves is described in the sec-
tion about coordinated moves.
Stored Programs
The instructions to execute the motion can be issued directly from
the host computer, resulting in an immediate move.This requires
the continuous involvement of the host computer.This require-
ment is often undesirable because the host may have to perform
other functions simultaneously. An alternative method is to com-
bine several motion commands into a complete application pro-
gram which is downloaded to the controller memory.This method
reduces or eliminates the involvement of the host computer.The
DMC can receive its instructions from stored programs.To start the
motion, the host sends a short command, such as XQ#A to execute
Program A.The controller will then receive the instructions from its
memory without the intervention of the host computer.(See exam-
ple on the next page.)
For example, let the encoder resolution be 4000 counts per turn and sup-
pose the objective is to rotate the motor one revolution along a trape-
zoidal velocity, with a total motion time of 0.3 sec with acceleration and
deceleration times of 0.1 sec each.Simple calculation indicates that the
slew velocity equals 5 revolutions per second and that both acceleration
and deceleration rates are 50 revolutions/sec
2
.The motion parameters
can be expressed in terms of units of resolution:a distance of 4000
counts, a slew velocity of 20,000 counts/sec,and acceleration and
deceleration rates of 200,000 counts/sec
2
.The motion parameters
must be transmitted from the host computer to the motion con-
troller.The special instructions used by the DMC, along with their
interpretation, are given below.
The host computer sends the characters indicated by the pro-
gram shown below and the motion starts immediately.
INSTRUCTION
INTERPRETATION
PR 4000
Relative distance
SP 20000
Speed rate
AC 200000
Acceleration rate
DC 200000
Deceleration rate
BGX
Start motion of X motor
Example--Point-to-Point
Another type of simple motion is the jog move.Here the motor is com-
manded to run indefinitely at a specified speed.The motion parameters
in this case are limited to speed, acceleration, and deceleration.These
parameters can be expressed in units of resolution as illustrated.
Consider a system where the resolution of the encoder is 4000
counts/turn and the motor is required to run at a speed of 600 rpm
(10 revolutions/sec) and must accelerate to that speed over 100
msec. Simple calculations show that the speed is 40,000 counts/sec
and the acceleration is 400,000 counts/sec2.
INSTRUCTION
INTERPRETATION
JG 40000
Jog speed
AC 400000
Acceleration rate
BGX
Start X motion
Example--Jog Move
SLEW SPEED
VELOCITY
ACCELERATION
RATE
DECELERATION
RATE
TIME
