Total beginner

[gmferg]

C2 is the one shot. You changed some of the tags in your logic from what was shown in the sample. Check all your replacements again and keep in mind that C2 is used as a one shot and should be an internal bit.

 

[dronai]

C2 is the one shot. You changed some of the tags in your logic from what was shown in the sample. Check all your replacements again and keep in mind that C2 is used as a one shot and should be an internal bit.

OK substituted as you suggested, I still dont know where to put the OSR. Does it replace the C2 N/O contacts ? Right now my momentary PB is doing just that on off for as long as I hold it ?

 

[milldrone]

I still dont know where to put the OSR.

It's not a OSR. It's using the scan order to make it into a oneshot.

Make the changes I have circled and it should work.

 

[dronai]

It's not a OSR. It's using the scan order to make it into a oneshot.

Make the changes I have circled and it should work.

It changed for the better, but it doesn't alternate, and stay on each output. Only one output stays lite, the other is momentary.

I have a diagram that works with a counter that does this perfectly, but I wanted to see this alternation done another way.

Thanks for your help.

 

[Lancie1]

It changed for the better, but it doesn't alternate, and stay on each output. Only one output stays lite, the other is momentary.

Dronai,

Milldrone has shown the logic for an alternator circuit (sometimes referred to as a "flip-flop" in slang language), with C1 alternating between on and off each time the Pushbutton is pressed. Forget the second output, because it is an intermediate device for internal use only.

Gosh, why did you not duplicate the logic precisely, instead of changing it all up and then expecting it to still work? I mean, you ask a question, you get a correct answer, then you go off in a different direction and ask why YOUR version didn't work? It did not work because you did not understand how it works, so you messed it up so that it couldn't work.

If it still doesn't alternate the "old C1" then you still have an error and have NOT duplicated Milldrone's logic.

It seems that you may be confusing this circuit with a One Shot, which is an entirely different function. What Milldrone was saying is that C2 acts as a One-Shot to control C1 (the main focus of this logic).

Here is the corrected program, with the first 3 button presses. I don't think it will work any differently if you press the button another 100 times.

 

[dronai]

Dronai,

Milldrone has shown the logic for an alternator circuit (sometimes referred to as a "flip-flop" in slang language), with C1 alternating between on and off each time the Pushbutton is pressed. Forget the second output, because it is an intermediate device for internal use only.

Gosh, why did you not duplicate the logic precisely, instead of changing it all up and then expecting it to still work? I mean, you ask a question, you get a correct answer, then you go off in a different direction and ask why YOUR version didn't work? It did not work because you did not understand how it works, so you messed it up so that it couldn't work.

If it still doesn't alternate the "old C1" then you still have an error and have NOT duplicated Milldrone's logic.

It seems that you may be confusing this circuit with a One Shot, which is an entirely different function. What Milldrone was saying is that C2 acts as a One-Shot to control C1 (the main focus of this logic).

Here is the corrected program, with the first 3 button presses. I don't think it will work any differently if you press the button another 100 times.

Sorry, I didn't know the other output was an intermediate device for internal use only.
I was thinking it was a One Shot !!

 

[Lancie1]

No, C2 is a regular old relay that acts sort of like a One-Shot function (due to the placement of bits and the fact that the OTE for C2 comes AFTER C1 in the program scan).

To Turn C1 ON: (1)The C2 XIO contact on the top rung branch is ON for only 1 scan after the Pushbutton is pressed. (2) On second scan and up until Pushbutton is released, C2 is ON and seals in C1 through the bottom branch of Rung 000. (3) The next PLC scan after the Pushbutton is released, C1 seals in through the XIO for Pushbutton Input X100 on the center branch of Rung 000.

To Turn C1 OFF: (1) On the first scan after pushbutton pressed, the Pushbutton XIO contact on the middle rung branch causes C1 to drop out. (2) On second scan and up until Pushbutton is released, C2 is ON and locks out C1 through the top branch of Rung 000. (3) On the next PLC scan after the Pushbutton is released, Input X100 is off, keeping C1 off.

 

[dronai]

No, C2 is a relay that acts sort of like a One-Shot function. The C2 XIO contact on the top rung branch is ON for only 1 scan after the pushbutton is pressed.

Lance, if wanted to use this to make the garage door opener project that all the students do, would this be a good choice ?

Or would you use 2 separate outputs (1) for up, and (1) for down. Or would you have a reversing motor using only one output ?

The limit switches seem like you could just use a N/C contact, and open it when the limit is reached.

Or even a timer for each operation, at a set time to reach the limits.

 

[Lancie1]

If you are doing the LogixPro Student Exercise for the Door Operner, then there are several parts. In the first few exercises, you use the Open button to energize the UP motor coil, and the Close button to energize the DOWN motor coil.

In the later more difficult exercises, you have to add other functions. One is that if the door is traveling UP and you press the DOWN button, it has to STOP. IF it is traveling DOWN and you press the UP button, it has to STOP. For this you CAN use some logic similar to the alternator logic. That will work.

However, if you follow the instructions (an important thing to learn about programming is that you are usually following a set of specifications), they want you to use "Flag" bits to allow the OPEN and CLOSE buttons each to perform two separate functions (Normal or STOP if Traveling functions) depending on if door is moving, or not.

Here is a link to the Instructions for the first LogixPro Door Simulation Exercise.
http://www.thelearningpit.com/lp/doc/dl/dl-rl.html

 

[dronai]

Thanks for the pointers. I saw the project Logixpro. I was just doing something on my own with my MicroLogix 1000 trainer I bought.

I have been taking motor control schematics, and converting them to logic for fun. and the challenge.

 

[Lancie1]

Your programs look good. You should get in the habit of adding Rung Comments. I know, it sounds silly for these simple, fairly obvious rungs. But if you don't do it for these, as you progress to higher levels of difficulty, you will say "well, I understand what is going on here, so no need to add explanations."

Then at some time in the future, you will find yourself troubleshooting one of your old programs and asking yourself "What the H#!! was I trying to do here?"

The rung comments do not have to be elaborate, only detailed enough to explain the Output. For example, you might want rung comments that say "Motor 1 Output" and "Motor 2 Output". Right away some will see that these two outputs could be lumped together, and controlled by internal relays. Many use these internal relays (B3 bits in your Micrologix) to do everything, only switching to Inputs and Outputs in a table at the end of the program.

 

PROGRAM INPUTS MAPPED TO INTERNAL BITS

| I:0/2                           |

| Motor 1 Start        B3/0       |

|---| |---------------(OTE)-------|

|                                 |

 

PROGRAM OUTPUTS MAPPED TO INTERNAL BITS

| B3/10                 O:0/0     |

| Motor 1 Run         Motor 1 Out |

|---| |----------------(OTE)------|

|                                 |

| B3/11                O:0/1      |

| Motor 2 Run         Motor 2 Out |

|---| |----------------(OTE)------|

|                                 |

 

[milldrone]

Your programs look good. You should get in the habit of adding Rung Comments. I know, it sounds silly for these simple, fairly obvious rungs. But if you don't do it for these, as you progress to higher levels of difficulty, you will say "well, I understand what is going on here, so no need to add explanations."

Then at some time in the future, you will find yourself troubleshooting one of your old programs and asking yourself "What the H#!! was I trying to do here?"

I'll second that

 

[dronai]

Your programs look good. You should get in the habit of adding Rung Comments. I know, it sounds silly for these simple, fairly obvious rungs. But if you don't do it for these, as you progress to higher levels of difficulty, you will say "well, I understand what is going on here, so no need to add explanations."

Then at some time in the future, you will find yourself troubleshooting one of your old programs and asking yourself "What the H#!! was I trying to do here?"

The rung comments do not have to be elaborate, only detailed enough to explain the Output. For example, you might want rung comments that say "Motor 1 Output" and "Motor 2 Output". Right away some will see that these two outputs could be lumped together, and controlled by internal relays. Many use these internal relays (B3 bits in your Micrologix) to do everything, only switching to Inputs and Outputs in a table at the end of the program.

 

PROGRAM INPUTS MAPPED TO INTERNAL BITS

| I:0/2 |

| Motor 1 Start B3/0 |

|---| |---------------(OTE)-------|

| |

 

PROGRAM OUTPUTS MAPPED TO INTERNAL BITS

| B3/10 O:0/0 |

| Motor 1 Run Motor 1 Out |

|---| |----------------(OTE)------|

| |

| B3/11 O:0/1 |

| Motor 2 Run Motor 2 Out |

|---| |----------------(OTE)------|

| |

I see your point on rung comments.

Secondly, I didn't know you could do what you showed in the example, but it makes perfect sense. Why make something an external Output, or input, if you could use internal bits, until the last outcome was ready for a field output, or input.