Galil DMC-1700 Wire Cutter, Example - Position Follower Continuous Move, 4000/2π = 637 count/inch

JP #Loop	Repeat
EN	End

Example - Position Follower (Continuous Move)

Method: Read the analog input, compute the commanded position and the position error. Command the motor to run at a speed in proportions to the position error.

INSTRUCTION	INTERPRETATION
#Cont	Label
AC 80000;DC 80000	Acceleration rate
JG 0	Start job mode
BGX	Start motion
#Loop
VAR=@AN[1]*1000	Compute desired position
VER=VAR-_TPX	Find position error
VEL=VER*20	Compute velocity
JG VEL	Change velocity
JP #Loop	Change velocity
EN	End

Example Applications

Wire Cutter

An operator activates a start switch. This causes a motor to advance the wire a distance of 10”. When the motion stops, the controller generates an output signal which activates the cutter. Allowing 100 ms for the cutting completes the cycle.

Suppose that the motor drives the wire by a roller with a 2” diameter. Also assume that the encoder resolution is 1000 lines per revolution. Since the circumference of the roller equals 2π inches, and it corresponds to 4000 quadrature, one inch of travel equals:

4000/2π = 637 count/inch

This implies that a distance of 10 inches equals 6370 counts, and a slew speed of 5 inches per second, for example, equals 3185 count/sec.

The input signal may be applied to I1, for example, and the output signal is chosen as output 1. The motor velocity profile and the related input and output signals are shown in Fig. 7.1.

The program starts at a state that we define as #A. Here the controller waits for the input pulse on I1. As soon as the pulse is given, the controller starts the forward motion.

Upon completion of the forward move, the controller outputs a pulse for 20 ms and then waits an additional 80 ms before returning to #A for a new cycle.

INSTRUCTION FUNCTION

#ALabel

DMC-1700/1800 Chapter 7 Application Programming • 169