AB Pico timer problem

Howdy all, I'm a total PLC noob and this is my 1st post.

I am using the AB Pico 1760-L12BWB-A. I want a momentary switch to activate a load for n seconds. Problem is, if the switch is pressed and released rapidly (< 0.5 sec~), the load activates and deactivates rapidly. When the switch is depressed slightly longer (> 0.5 sec~), the load remains on for n seconds as expected. The timer contact is closing in both cases, but not remaining closed in the first case. Any ideas why, and how to remedy this? Here is my ladder:

--| I01 |-----( T01 )--



--| T01 |-----( Q01 )--

Best,
Harry

I01 is momentary. What do expect to hold the T01 timer ON once the button is released?

Not enough detail to make a complete idea, but I would use |Q01| in a branch below |I01|

 

             T01

--| I01 |--+-|\|--( Q01 )--

           | 

--| Q01 |--+

 

 

--| Q01 |-----( T01 )--

Make sure timer parameter is On-delayed.

sounds like a flip flop problem do a search on this site there is plenty of examples however due to the limits on Pico's instructions here is one way you can do it

lol Jrwb4gbm also posted a good solution at the same time mine was post
edit I misread your problem and had the output coming on 5 sec later in my example use the Jwr's example

Stranger and stranger...

jrwb4gbm said:

 

             T01

--| I01 |--+-|\|--( Q01 )--

           | 

--| Q01 |--+

 

 

--| Q01 |-----( T01 )--

Make sure timer parameter is On-delayed.

Click to expand...

Thanks for your reply. Your solution should work, but I get the same result. After extensive testing, I've observed:

1. Briefly close I01 (<0.5 sec~) once, Q01 briefly activates, but T01 fails to latch open.

2. Hold I01 closed for >0.5 sec, and the circuit latches until T01 times out as expected.

3. Briefly close I01 again, in 8 seconds or less, and T01 latches Q01 as expected. Subsequent brief closures of I01 work as expected, for about 2 minutes.

4. Briefly close I01, get momentary output without timer latching, wait more than 8 sec~ and retry, get the same (incorrect) momentary output. I can repeat this all day long, but once I close input I01 in 8 seconds or less, I get the same result as (3) above.

How can Q01 fail to initialize the timer T01? Is the Pico controller so slow that it takes more than 0.5 sec to initialize T01? I have no info on the cycle speed; is there any possibility that the Pico PLC is too slow, or even defective?

Thanks in advance.

If you are observing this as behavior on an actual output on the plc instead of the software presentation on your computer, I really dont know the answer. I can only run this in simulator mode on my computer since I dont have the actual plc hardware. I too have observed some of the problems while running in Simulator mode.

I run into the same problem cannot get it to fail in simulation and don't have a spare Pico to test it

I went and checked the manual and they already have a flip flop available when you set Q01 goto parameters and enter select impulse relay try that if that does does work try chnaging the Q01's to marker on the output and the Or statement. then use marker to activate your output as stated I have no Pico available to test if the reaction time is fast enough however I do not believe your problem is cycle time it may be that the output takes too long to activate after a fast input trigger to latch in. So we should be able to correct that with one of the two methods I described

I wrote this and found a PICO controller to test it on I used a 2 sec timer on TT1 and a 5 sec Timer on TT2 more for testing purposes to make sure everything triggers correctly you will need to determine when you want to reset the Immediate QO1.

However no matter how fast I triggered input 2 this worked