I am embarking on writing a program for my DL05 PLC that will control a small sanding operation. Components included are: 2 swing clamps, linear actuator, air manifold, precision regulator, and sanding machine. The actuator, and 2 swing clamps are controlled by compressed air which is regulated by the manifold. The flow of this process will be:
1. Operator puts part in fixture and presses start button on sander
2. PLC program begins:
a. Sander turns on
b. Swing clamp contact on manifold engages, air flows to two clamps holding part in fixture
c. Actuator contact on manifold engages, air flows to actuator extending actuator (moving part to sandpaper)
d. Precision regulator holds air pressure to actuator at 20 lbs.
e. Actuator moves part to make contact with sandpaper, held in this position for 6 seconds
f. After 6 seconds, 2nd actuator contact on manifold engages, air flows to actuator retracting actuator (moving part away from sandpaper)
g. Sander turns off
h. 2nd swing clamp contact on manifold engages, supplies air to both clamps to release clamp from holding part
3. Operator takes part off of fixture, puts next part on
4. Operator presses start button, process starts again
The first thing that needs to be done when writing a PLC program is to make a description of the process. I'm having a little difficulty with your description. It might just be a terminology thing. I going to attempt to write a description of your process from what I have just read. I will also ask some questions along the way.
1. Operator presses start button.
2. "Sander motor" output from the PLC turns on. Do we need a time delay for the motor to come up to speed? If this is an electric motor, You do realize that the PLC cannot turn this on directly but will need some sort of interface?
3. "Swing clamp down" output turns on in the PLC. Do we need some time delay before the next step? Also you are saying there is two "contacts" as you are calling them for the clamps. Are they "clamp" and "unclamp" or are they two coils one for each clamp?
4. "Actuator extend" output from the PLC turns on. Do we wait six seconds from this moment or do we wait until the actuator is in position? If we wait six seconds when it's in position then we need a in position sensor.
5. "Actuator retract" output from the PLC turns on. Are you sure there is two coils for the actuator? Extend and retract? do we need a time delay after the retract output has been turned on before the next step or is there a home sensor?
6. Turn off the "sander motor output from the PLC. Do we need another time delay before the next step?
7. "Swing clamp up" output from the PLC turns on.
The safety aspects Controls Guy mentioned need to addressed. Safety is done outside the PLC, not in the program.
We need details on the nature of the loads the PLC is expected to control. 120V AC, 24VDC, amps ect.
Do you want help writing the program? This is an excellent type of project to start learning PLCs with! Or do you just want the code? I'm hoping you want just some nudges from us to get you started. I'm sure we will do our best to help you.