Input Protection Lines; Software Protection; Programmable Position Limits - Galil Motion Control DMC-18 2 Series User Manual

Input Protection Lines

Abort - A low input stops commanded motion instantly without a controlled deceleration. For any
axis in which the Off-On-Error function is enabled, the amplifiers will be disabled. This could cause
the motor to 'coast' to a stop. If the Off-On-Error function is not enabled, the motor will
instantaneously stop and servo at the current position. The Off-On-Error function is further discussed
in this chapter.
Selective Abort – The controller can be configured to provide an individual abort for each axis.
Activation of the selective abort signal will act the same as the Abort Input but only on the specific
axis. To configure the controller for selective abort, issue the command CN,,,1. This configures the
inputs 5,6,7,8 to act as selective aborts for axes A,B, C, D respectively.
Forward Limit Switch - Low input inhibits motion in forward direction. (The CN command can be
used to change the polarity of the limit switches.) If the motor is moving in the forward direction when
the limit switch is activated, the motion will decelerate and stop. In addition, if the motor is moving in
the forward direction, the controller will automatically jump to the limit switch subroutine, #LIMSWI
(if such a routine has been written by the user).
Reverse Limit Switch - Low input inhibits motion in reverse direction. (The CN command can be
used to change the polarity of the limit switches.) If the motor is moving in the reverse direction when
the limit switch is activated, the motion will decelerate and stop. In addition, if the motor is moving in
the reverse direction, the controller will automatically jump to the limit switch subroutine, #LIMSWI
(if such a routine has been written by the user).

Software Protection

The DMC-18x2 provides a programmable error limit. The error limit refers to a difference in the
actual and commanded position of the motor. This limit can be set for any number between 1 and
32767 using the ER n command. The default value for ER is 16384.
Example:
ER 200,300,400,500
ER,1,,10
The units of the error limit are quadrature counts. The error is the difference between the command
position and actual encoder position. If the absolute value of the error exceeds the value specified by
ER, the DMC-18x2 will generate signals to warn the host system of the error condition. These signals
include:
Signal or Function
# POSERR
Error Light
OE Function
AEN Output Line
The Jump if Condition statement is useful for branching within the program due to an error. The
position error of X,Y,Z, and W can be monitored during execution using the TE command.

Programmable Position Limits

The DMC-18x2 provides programmable forward and reverse position limits. These are set by the BL
(Backwards Limit) and FL (Forward Limit) software commands. Once a position limit is specified,
the DMC-18x2 will not accept position commands beyond the limit. Motion beyond the limit is also
prevented.
150 ● Chapter 8 Hardware & Software Protection
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Set X-axis error limit for 200, Y-axis error limit to 300, Z-axis error limit to 400
counts, W-axis error limit to 500 counts
Set Y-axis error limit to 1 count, set W-axis error limit to 10 counts.
State if Error Occurs
Jumps to automatic excess position error subroutine (if included in program)
Turns on
Shuts motor off if OE1
Goes low
DMC-18x2