Output question with Logix 500

tacm · Oct 16, 2008

Hi Guys, on line 5 of the following code. What is the easiest way to keep that output energised for 3/4 of a second. TOF? Latch and then unlatch with timer?
Thanx

widelto · Oct 16, 2008

Use xic from t4:2/dn, this should trigger a new bit b3/3 just for a scan ( use a ONS ), next rung b3/3 will start a new timer with a preset of 3/4 secs ( 75=pre, time base=.001), mantain that timer on with timer/EN ( use a branch), then and use XIO timer/dn on the same rung to turn off timer, in paralell with timer use a branch and put your solenoid O:0/3, this way your solenoid wil stay on as long as your time is on i.e. 3/4 of a sec.

randyk · Oct 16, 2008

Put a TON activated by T4:2/DN in the program and on line 5 use an XIO/DN from the TON that will shut it down after the 3/4 second.

Brownhat · Oct 16, 2008

I think that the "timer timing" bit is generally under-utilized. You could also do it like this:

widelto · Oct 16, 2008

Brownhat shows it as i explained it, that´s the way.

tacm · Oct 16, 2008

How are you reseting it for the next pulse?

OkiePC · Oct 16, 2008

It will reset when T4:2/DN is no longer true, and T4:3/TT is no longer true...
So, it will ensure that the output is energized for a duration equal to T4:3.PRE each time that T4:2/DN makes a false to true transition.

Actually, I think you'll want to do away with the TOF T4:2, and trigger the logic as brownhat posted by replacing XIC T4:2/DN with T4:1/EN or DN depending on when you want the output to energize.

randyk · Oct 16, 2008

You don't have to reset it when power is taken off the TON and then reapplied it will start at zero.

Already explained by OkiePC, must have posted seconds before me.

magicsmoke · Oct 16, 2008

or you can do it this way

Tharon · Oct 16, 2008

I usually use the .EN seal in with a not .DN drop out as well. It's closer to the basic start/stop circuit and easier for a lot of people to understand.

robertmee · Oct 16, 2008

Sorry, but I abhor the use of TOFs...If it were mine, I'd do it like this. Check my math, this was quick off the top and prone to mistakes, but if I understand your logic, you are wanting to pulse a solenoid for 1800 seconds with a frequency of every 60 seconds for a duration of .75 seconds. The only caveat is that the first pulse is at time 60, not time 0. If that's a problem there's an easy fix.

Output question with Logix 500

tacm

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