I am using a panelview 550 to control a micrologix 1000. I have a numeric entry button indexing N7:0 pointing at 4 equal instructions. If the operator presses 1-4 the corresponding equal instruction will trigger a TOF timer affecting a few outputs on the micrologix.

It works, but it does not seem to reset. If I use manual pushbuttons the timers work fine, but this way I don't get the same time output every time. I can't hook up my panelview and my laptop at the same time to see what is happening. Do I need to reset the equal instructions somehow?

 

The TOF instruction sets the /DN bit as soon as the preconditions are true, and runs the timer after the preconditions go false. When you use a numeric entry element in a PanelView, the value is placed in the target data element and is not changed until another value is entered.

It sounds like you essentially want the numeric entry value to behave like a momentary pushbutton.

The easiest way to do this is to put a rung below the EQU/TOF rung that moves a zero into N7:0 if N7:0 is nonzero.

EQU N7:0 0 MOV 0 N7:0

 

Hi Tom,
Not quite sure what you are trying to do, but with the numeric entry it will write the value into N7:0 and the EQU will be true, then the DN bit for the timer will be true. If you used 4 different TOF's, then when a different vale is written the timer should start timing if it no longer is true in the EQU. A little more info on your program or what you are trying to achieve and we could give you more of an idea.

Trevor.

 

You need to clear the integer address after you have done what you need it to do!! The PV doesn't do it for you.

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Thanks for the reply. I need to have the operator enter a program number in the panelview, 1 to 4. The plc needs to start a different timer corresponding to the different numbers. When the timer starts, 4 outputs come on and stay on until the timer stops. To test I made the timers 5, 10, 15, and 20 seconds. I cannot do one timer twice in a row. and if I do timer 1, it works fine. If I then do timer 2, it works fine, but if I go back to timer 1, it may be 10 or 15 seconds instead of 5. I set N7:0 comparing the input 1-4 to 4 equal instructions 1-4. The timers reset when the rung goes true again, I'm not sure what the problem is.

 

Hi Tom,
I would do what Jeremy mentioned, with the last rung use a NEQ when N7:0 does not equal 0 then CLR N7:0 and the TOF timer will time.

Cheers,
Trevor.

 

> If I use manual pushbuttons the timers work fine, but this way I don't get the same time output every time.<

How about using a one-shot on the button? That should give consistent timing.

Regards
cww

 

You are probably using the "Set Value" type pushbutton, which sends an integer to the PLC each time the button is pressed. It always goes through the same sequence of numbers, e.g., 1-2-3-4-1-2-3-4-1-2-3-4-etc. If you want to skip numbers or back up, you could use 2 buttons. The "set Value" button to select the timer routine, and then a "Start" button to start the selected operation.

Or you could use a numeric entry button and input directly the routine # you wish to run.

There are dozens of ways to do this. Ten programmers would use ten approaches, ranging from using a pointer and indirect addressing, to simply having four buttons to choose from.

Bruce A.

 

Thanks again. That is what I ended up doing, using 4 buttons. Eventually there will be alot more programs and that won't work anymore,