Rockwell Automation 1761-HHP-B30 MicroLogix 1000 with Hand-Held Programmer (HHP) - Manual (Page 477)

Appendix E
Application Example Programs
E–34
The following application example illustrates how the controller high-speed
counter is configured for the up and down counter using an encoder with
reset and hold. For a detailed explanation of:
•
LD, LDI, OUT, RES, SET, RST, and TON instructions, see chapter 8.
•
GRT and NEQ instructions, see chapter 9.
•
MOV instruction, see chapter 11.
•
HSC and HSL instructions, see chapter 14.
A
Gripper O:0/0
Conveyor
B C D E G F H
Rail
Encoder
A – I:0/0
B – I:0/1
C – I:0/2
Master PLC Outputs
Wired to Inputs:
I:0/5
I:0/6
I:0/7 Home Position
Storage Bins
Pick and Place Machine Operation Overview
A pick and place machine takes parts from a conveyor and drops them into
the appropriate bins. When the pick and place head is positioned over the
conveyor with a gripped part, the master PLC communicates to the controller
controlling the gripper which bin to drop the part into. This information is
communicated by energizing three outputs that are wired to the controller’s
inputs.
Once the controller has this information, it grabs the part and moves down
the rail. When the gripper reaches the appropriate bin, it opens and the part
falls into the bin. The gripper then returns to the conveyor to retrieve another
part.
The position of the pick and place head is read by the controller via a 1000
line quadrature encoder wired to the controller’s high-speed counter inputs.
When the gripper is in the home position, the Z pulse from the encoder resets
the high-speed counter. The number of pulses the head needs to travel to
reach each bin location is stored in a data table starting at address N10 and
ending at N17. The controller uses indexed addressing to locate the correct
encoder count from the data table and to load the information into the high
preset of the high-speed counter.
Pick and Place Machine
Example