Rockwell Automation 1785-LTx,D17856.2.1 Classic PLC-5 Programmable Controllers Users Manual - Manual (Page 75)

Planning Your System Programs
Chapter 6
6-4
Organizing a Machine Example
This section uses an example of a specific machine operation to show how
to identify conditions and actions and how to group the actions into steps
of machine operation.
Figure 6.1
Hardware Block Diagram and Description of Machine Process
FW D
Conveyor
M otor
O FF
AUTO
Advance
Assem bly
Drill
M otor
N C
N O N O
LS1
LS5
FW D
Clam p
CL1
LS4 LS3
LS2
Held O pen
. .
. . . .
N O . .
N O . .
FW D
L oad
St a t i on
l oad
St a t i on
U n
A description of this operation might be as follows:
1. The operator starts the conveyor by selecting AUTO.
2. The operator puts a block of wood onto the conveyor.
3. The wood moves into position and actuates LS1.
4. When the wood is in position:
a.
the conveyor stops
b. CL1 clamps the wood
c. the drill station moves forward
5. The drill station moves forward and closes LS3. This
action turns on the drill motor.
6. The drill station moves to full depth and closes LS4. This action:
a.
stops forward motion of the drill station
b. initiates a 2Ćsecond dwell
7. The drill station backs up after the 2Ćsecond dwell.
8. The drill motor stops when LS3 is released.
9. The drill station reaches home position and opens LS2. This action:
a.
stops the reverse motion
b. opens the clamp
c. starts the conveyor forward
10. The wood is ejected when LS5 toggles to indicate that the cycle is complete.