I have trouble understanding why Limit UpSW and Limit DwnSW were changed from "true if on" to "true if off" aka -] [- to -]/[- at around 4:30. It was my understanding that the "limit" bit would turn off once the garage door was fully open because the limit switch opens, thus the transistor does not conduct and the bit turns off.
plcprofessor Thank you for the quick response. Yes I have watched those lectures. I assume you're referring to ~37:00 of Pt. 2. I gathered that limit switches are held against their normal state so when the pressure or presence of the equipment is removed a Normally Open Held Closed limit switch opens and a Normally Closed Held Open limit switch closes. I think I might understand why you made the change now. A Normally Open, Held Closed (by the equipment) limit switch would set the Limit UpSW bit on when the garage door is fully open and the pressure is on, so to speak. When the pressure of the door is removed, the limit switch returns to its "normal state" of open, and the transistor no longer conducts so the Limit UpSW bit turns off. Since the door should only travel upward when the door is not in its fully open you use the "true if off" Limit UpSW permissive to activate the upward motor. By the way, I love all of your videos so far. You've done a great job explaining everything so that it's easy to understand. I get a bit pedantic with these kinds of topics so I'm not surprised that I'm confused.
Sophie Schneider Keep in mind that those limit switches normally have both NC and NO contacts so you can take your pick. My actual choice would be towards safety in that... if the wire breaks or the switch falls apart that the resulting state not allow the system to move the door until you fix it. Either combination will work as long as your logic considers that the door is not up or down or that it is up or down and the motor does not drive the door any further in that direction.
Following the tutorials, I entered the logic for the single switch in the RSLogix Micro Starter Lite, but when I try to simulate, though the unlink toggles the push button as expected, for some reason, the OSR never toggles on so none of the up/down/stop actions take place. Am I missing something?
Please ignore this, found out by following the final video that I had chunks yet to be added. Thank you very much for these tutorials, I am studying them in preparation for an interview and they are invaluable. :-)
I don't understand the top rung. From the ladder logic, it would be: IF the Motor is going UP OR the Motor is going DOWN STOP As soon as the motor is energized, wouldn't it immediately stop the motor?
Yes you said That you were thinking about doing a latter logix on convayer belt systems Did you do this yet. I am in final Qt. Cap stone project time. would like to here from you
Again, PLC Prof. you had done a great job.
I have trouble understanding why Limit UpSW and Limit DwnSW were changed from "true if on" to "true if off" aka -] [- to -]/[- at around 4:30. It was my understanding that the "limit" bit would turn off once the garage door was fully open because the limit switch opens, thus the transistor does not conduct and the bit turns off.
Have you watched PLC Lecture 01 Pt.1 and Pt.2? If you go to the Playlist, they are the two lectures in the replacement list.
plcprofessor Thank you for the quick response. Yes I have watched those lectures. I assume you're referring to ~37:00 of Pt. 2. I gathered that limit switches are held against their normal state so when the pressure or presence of the equipment is removed a Normally Open Held Closed limit switch opens and a Normally Closed Held Open limit switch closes.
I think I might understand why you made the change now. A Normally Open, Held Closed (by the equipment) limit switch would set the Limit UpSW bit on when the garage door is fully open and the pressure is on, so to speak. When the pressure of the door is removed, the limit switch returns to its "normal state" of open, and the transistor no longer conducts so the Limit UpSW bit turns off. Since the door should only travel upward when the door is not in its fully open you use the "true if off" Limit UpSW permissive to activate the upward motor.
By the way, I love all of your videos so far. You've done a great job explaining everything so that it's easy to understand. I get a bit pedantic with these kinds of topics so I'm not surprised that I'm confused.
Sophie Schneider Keep in mind that those limit switches normally have both NC and NO contacts so you can take your pick. My actual choice would be towards safety in that... if the wire breaks or the switch falls apart that the resulting state not allow the system to move the door until you fix it. Either combination will work as long as your logic considers that the door is not up or down or that it is up or down and the motor does not drive the door any further in that direction.
what is the max number of rungs you can write on rslogix microstarter lite???
Following the tutorials, I entered the logic for the single switch in the RSLogix Micro Starter Lite, but when I try to simulate, though the unlink toggles the push button as expected, for some reason, the OSR never toggles on so none of the up/down/stop actions take place. Am I missing something?
Please ignore this, found out by following the final video that I had chunks yet to be added. Thank you very much for these tutorials, I am studying them in preparation for an interview and they are invaluable. :-)
I don't understand the top rung. From the ladder logic, it would be:
IF the Motor is going UP
OR the Motor is going DOWN
STOP
As soon as the motor is energized, wouldn't it immediately stop the motor?
Yes you said That you were thinking about doing a latter logix on convayer belt systems Did you do this yet. I am in final Qt. Cap stone project time. would like to here from you
Thanks, I like what you are doing here.
you always end up saying thank you. I don't know what to say, but thank you very much for your work
Thank you too!
I understood all the video up to this this point at the OSR. Any words of wisdom professor?
In the Basics playlist, there is a presentation specifically on the one shot instruction.
Thank you professor, I'll check it out.
Pl;aylist RSLogix 5000 multiple programs
this video is not clear