NEWBIE DL 05 question

I am very new to plc programming and i am looking for help for a program I am writing to remotely turn on/off an air compressor. I currently have a program written that uses a timer to time an output off after a three second delay. the timer is started by a normally closed contact off of an input, when the input goes low I need the machine to shut off after three seconds. Currently to turn on my output I have a rung of logic that has (timer not equal to zero) anded to (timer is less than 3 seconds) this is ored to a normally open contact that pulls in with the input. so the normally open contact holds the output closed until the contact opens, then the timer starts timeing and the first rung described above locks in the output for three extra seconds and then the output goes off. the problem is there is sometimes a "flap" of the contact caused by it taking one extra scan to read that the timer is not zero (I assume). what is the correct way to time off an output to get rid of this momentary change of state??

BgScott,

Can you post your code? You can do a screen print, paste it to MSpaint and save it to a jpg file, then attach it using the Browse button in the "post reply" page.

If I'm reading your post correctly, you want to delay off your compressor by 3 seconds.

thanks for the help, and thanks for the info on how to post, I am a first timer at this.

unfortunately Direct Logic PLC's do not have an off delay timer. on the base models they only give you a timer that times and a counter that counts, it is then up to the programmer to come up with on delay, off delay, and that sort of thing. I am stuck trying to figure out how to get an off delay.

My logic needs one input and two outputs. output one needs to be high when the input is high, and needs to go low immediatley when the input goes low. it needs to stay low for a few seconds and then go back high until the input does an high low transition again.

Output two needs to go high when the input is high, and then time off after a few seconds (8 now but that is not critical, its just critical that output one goes off for a few seconds before output two). it should stay low until the input is high.

thanks again for the help.

Bgs,

If I'm reading you right,

When input one goes on the following occurs:

1) Output one (always on when input is off) goes off for 8 sec then comes on and stay one untill the next input one off to on transition.

2) Output 2 goes on only when input 1 is on, and stays on 3 seconds after input one goes off. After delay time output 2 goes off.


Did I get that right??

Mike

that is correct sir.

Any time you want a delay on or off any timer that counts will do the job, just activate it with the condition to start a timer then use either T0 or a compare to activate a bit. This bit, as an XIC, is placed in front of the output that needs turned off. Also reset the timer with the same bit.

Did this make sense?

This is your code.

X0 is the control input.

Y1 will go on when X0 goes on. Y1 will go off 3 seconds after X0 goes off.

Y2 will go on when X0 is off.

When X0 goes on, Then Y2 will go off for 8 seconds and go back on.
Y2 will stay on untill X0 goes on again.

Check it out and let me know..

Looks like that will work. thanks, I was making this much harder than it had to be!!

I must admit I thought your code was the formula for cold fusion.

Remember to try programming with the basics first, than move on to the other more complex instructions later.

When programming, or requesting assistance, be sure to make it clear to your self, and others what the desired end result should be. There are a lot of ways to skin a cat, and everybody has different ideas. So the best way is to do a flow chart first, then write the code.

Good luck with it.

Mike.