MOTION PROGRAMMING
TECHNICAL REFERENCE
I/O INTERFACE, TRIPPOINTS
Another function of advanced motion controllers is to
schedule or sequence events in a program. These functions
are scheduled by delaying the execution of each function
until a certain condition occurs. These conditions are
called trippoints.
For example, the "After Distance" (AD) trippoint delays
the execution of a function until after the motor moves a
certain distance. Similarly, the execution of a function can be
delayed until a move has been completed (AM), an input sig-
nal changed states (AI), or by a pure time delay (WT).
The following example illustrates the use of trippoints in
executing a motion cycle.
It is often desirable to synchronize motion with input/out-
put (I/O) events, which enables the controller to control a
complete process. As such, the DMC can read input signals,
both digital and analog, and can generate digital output sig-
nals. Inputs may be control signals from digital push but-
tons or analog potentiometers. Outputs can be used to acti-
vate solenoids or valves or to turn on indicator lights.
Input signals, both digital and analog, can be read by the
controller and their values can be stored in control vari-
ables. These variables may be used later in motion pro-
grams.
The reading of digital inputs may be performed with the
instruction:
DIGITAL = @ IN[2]
which reads the digital input #2 and stores its content, 0 or
1, in the variable DIGITAL. Analog signals are similarly
read with the instruction:
ANALOG = @ AN[3]
which reads analog input #3.
Digital output signals are generated by setting or clearing
a bit with the instructions:
SB 3
CB 3
which sets and clears output bit #3.
The interface with the inputs and the generation of the
output signals allow the controller to perform complete
process control without a host computer intervention. This
is illustrated by the following example.
I/O INTERFACE
TRIPPOINTS
Consider the simple case where the motion of X must be
delayed until the start pulse is given (applied to input 1).
When the motion is completed, an output signal (output 1)
must be given for one second.
INSTRUCTION
INTERPRETATION
PR 7000
Distance
SP 5000
Speed
AI 1
Wait for start signal
BGX
Start motion
AMX
Wait for completion
SB 1
Set output 1 high
WT 1000
Wait 1 second
CB 1
Clear output 1
EN
End of program
Example--Start Motion on Input
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