Specifications

Program Example 2: Automatic Trapezoidal Profile with External Interrupt
Registration Applications:
1. In a typical application shown to the right,
product material in work moves past a work tool
such as a drill. Registration marks on the scrap
area of the work-piece allow a machine tool to
register its position relative to the rectangle, to
drill properly.
2. In other examples of registration, the work
piece is stationary and the tool moves. A drill bit
may approach the surface of a part in work,
preparing to drill a hole of precise depth.
However, the drill bit length gradually decreases
due to tool wear. A method to overcome this is to
detect the moment the drill makes contact with the surface of the part each time a part is
drilled. The bit can then drill a constant depth after making contact with the part’s surface.
3. The home search move allows a motion system to calibrate its position on startup. In this
case, the positioning system makes an indefinite move and waits for the load to pass by a
home limit switch. This creates an interrupt at the moment when the load is in a known
position. We then stop motion and preload the position value with a number which equates
to the physical “home position”.
When an interrupt pulse occurs on physical input X1, the starting position is declared to be
the present count (current load position). The velocity control switches to position control,
moving the load to the target position. Note that the minimum starting velocity is 40 pps.
This instantaneous velocity accommodates stepper motors that can stall at low speeds.
The time line of signal traces below the profile indicates the order of events. The CPU uses
logical output Y0 to start the profile. Immediately the HSIO turns off the Profile Complete
signal (SP104), so the ladder program can monitor the move’s completion by sensing the
signal’s on state.
DL06 Micro PLC User Manual, 3rd Edition, Rev. C
E–50
Appendix E: High-speed Input and Pulse Output Features
1
2
3
4
E
6
7
8
9
10
11
12
13
14
A
B
C
D
Registration Profile
Time
Accel Decel
Velocity
Start
position
Tar get
position
Target Velocity
Starting
Velocity
Start
External Interrupt
Y0
X1
Profile Complete SP104
Detect contact
Finished part area
Scrap
Area
Registration marks
direction of motion