Momentary Pushbutton HELP

See atcched pic. Help me to get it working. Normally the green light will be blinking with one sec delay. When you press a Pushbutton (X2) it should stay ON. Since my pushbutton is momentary, seems like it will turn ON green light permanently only if the Green light is ON(blinking. Seems like I need some kind of latch when you press the X2 push button. But I want to turn it OFF when I press it again. Any help is appreciated!

Thanks

I don't think X2 would be a pushbutton. I think it is monitoring a condition ('Control Power' possibly?) which would not be momentary.

Yea! Thats what I meant.

Am sorry replied too quick. Anyway am newbie ti PLC. Basically X2 is an input from the Stand Power ON push button. Same PB is used for turning it OFF too. You just have to push this button momentarily to turn it ON. Push it again will turn OFF the stand. Hope this helps.

lilocomotiv said:

Normally the green light will be blinking with one sec delay. When you press a Pushbutton (X2) it should stay ON. Since my pushbutton is momentary, seems like it will turn ON green light permanently only if the Green light is ON(blinking. Seems like I need some kind of latch when you press the X2 push button. But I want to turn it OFF when I press it again. Any help is appreciated!

Thanks

Click to expand...

lilocomotiv, Your description doesn't say anything about the Items I circled. What are these supposed to do?

I can't speak for Bernie but I'm having a little trouble with your description. Based on my interpretation of your description and your screenshot this is what I came up with.



.

Milldrone, that is also how I interpreted the description.

Lilocomotive, What we are missing is what the purpose of the Auto_PB, Manual_PB, Caution_PB, Warning_PB and Sentry_Relay with respect to the green light. If the intent of these is to unconditionally turn off the steady on green light and return it to flashing, then you could place them in series in front of C101 - rung 2, of milldrone's example - that would reset the flip-flop.

Second rung you marked is to turn ON the GREEN light permanently. AUTO PB is for the blue light, caution PB is for the AMBER light and Warning is for the RED light in a light stack. Sentry relay is a relay to enable the sentry system. Now just to make sure, this flip flop contact you mentioned is just another conatct right? Thanks

A flip flop is a bit with logic to change state whenever a conditon is true. If the input is a push button and the bit is off, pushing the button will turn the bit on. If the bit is on and the button is pushed, the bit will turn off. On....Off....On....Off, etc.

There are probably hundreds of threads on this forum about flip flops - you can use the search function to find them if you want to know more.

lilocomotiv,

Alaric has given you the correct info. Your response leads me to think that you are not understanding what we are saying.

lilocomotiv said:

Second rung you marked is to turn ON the GREEN light permanently.

Click to expand...

First a little correction: what I marked is a branch of the only rung you posted.

The reason I circled the items was to ask you what the purpose of the Auto_PB, Manual_PB, Caution_PB, Warning_PB and Sentry_Relay with respect to the green light.

lilocomotiv said:

AUTO PB is for the blue light, caution PB is for the AMBER light and Warning is for the RED light in a light stack. Sentry relay is a relay to enable the sentry system.

Click to expand...

Alaric had suspected this was what they were for and suggested a method for having them control the green light.

Alaric said:

If the intent of these is to unconditionally turn off the steady on green light and return it to flashing, then you could place them in series in front of C101 - rung 2, of milldrone's example - that would reset the flip-flop.

Click to expand...

I have included some rung comments to help you understand how this works.

lilocomotiv said:

Now just to make sure, this flip flop contact you mentioned is just another conatct right? Thanks

Click to expand...

The address C101 (flip flop)is an internal bit that exists in the virtual world inside the plc. The address C100 is another bit inside the PLC. In your case the first thing you must determine is if this address is already being used.

If you have any questions post back.

When you press a Pushbutton (X2) it should stay ON. Since my pushbutton is momentary, seems like it will turn ON green light permanently only if the Green light is ON(blinking.

Click to expand...

Lilocomotiv, in this case the condition of the Green light will NOT affect the way X2 works. Becasue X2 is a parallel branch, when it is ON, the Green light will be on. Period.

I agree with Bernie. Your X2 is labeled "Control Power Sensor". If this is not true, then you need to correct the label to describe what it actually is, a Pushbutton (if you are correct).

However I do not believe that X2 is a pushbutton, and the difference between a pushbutton and a Control Power Sensor relay (that may be partially controlled by a pushbutton) is large enough to keep you from ever getting the logic to work.

Now, studying your rung carefully, I do see a Pushbutton C1, and it will turn on the green light and latch it on (whether or not the light is blinking) IF the Auto, Caution, and Warning pushbuttons are all off AND the Sentry relay Y0 is on. Did you mean to refer to Pushbutton C1?

PS: What in the heck are Caution and Warning pushbuttons? I have seen Caution and Warning lights but never have I seen those functions carried out by pushbuttons. (This is a new type of retro-control, I suppose, where the burden for safety is put back on the operator!) Are you sure that you should not relabel these to be Lights instead of pushbuttons?

You may think these little errors are just human nature, unimportant, and you don't have time to fool around with them. If you think like that, then you need to change to another field. I tried to think of a career where details do not much matter, but I could not come up with one. Anyone have any suggestions? Maybe a TV news reader, where someone else makes the decisions about what is important and writes the scripts for you to read?

That aside, a momentary button that turns something on the first push and turns if off the next push, is a common problem and has been solved, discussed, and beat in the head in past posts on this forum. Do an "Advanced Search" for keywords alternator, toggle, or flip-flop (although techincally it is not a flip-flop).

How does it flash, what are the normal conditions of the parallel branch?

Milldrone has asked twice about that branch and you have not replied.

If the pushbuttons on that branch are normally on and the sentry relay is on, then as soon as the control enable comes on and the flash bit comes on, the second branch will maintain!!!

X2 doesn't change anything in that case.

It looks like you only get the flash if you have lost the sentry relay. Only in that case does the X2 contact override the flash.