How can i automate a push button

[Debnil]

I have a valve which has 2 possible positions, open and closed.  The valve is controlled via a PLC.  Currently, this is how the valve is being run:

1.  The operators click a push button labeled "open valve" which is a latched output remote push button

2.  They monitor an integral output which states the current feed level in a tank

3.  Once the level reaches the desired value, they click a "close valve" push button to close the valve and it closes and the feed level integral stops.

I want to automate the above process and have setup a new pot for a setpoint and also a sequencer.  I also created a "Start Process" push button and a "Reset" push button.

The operators want the process to be completely automated.  They want to:

1.  Input a setpoint

2.  Click the "Start Process" push button.

3.  Lookout needs to open the valve, monitor the intergral...Once the integral>= setpoint, lookout needs to close the valve

I am trying to determine how i can simulate the output that occurs when a human pushes the open valve button and close valve button to control the valve.  Which data member can I manipulate to simulate a human pushing the open valve and close valve button?

[hdp]

I was with you 'til the last paragraph.  I don't know your requirements but, a sequencer seems like overkill.

How about this: The 'start' button sets a flip-flop object, the output of which drives the "fill" output.  When the 'tank level' signal reaches or exceeds your setpoint, reset the flip-flop to stop the fill.

[Debnil]

Thanks, I didn't know about the flipflop object.  I will use it instead of a sequencer.  My problem however, is the valve is setup like this:

There are 3 variables within the plc that controls the valve, 2 are inputs, 1 is an output.  The output variable is a feedback variable.  The other 2 are open valve and close valve inputs.

The pushbuttons are setup the following way:

The open and closed valve buttons are latched output buttons.  Once they are pushed, they will not rise until the valve is open.  The problem I have been having is with the latched output.  If i link it to the flipflop, the button just stays pressed down and does not rise after feed back is received.  Does anyone know a way around this?

[Hooie]

Maybe you could change the push button from a latch to a momentary and a different stop. Change the indicator to the output used for the valve. You can have the the level as a contact in series with the open valve and again with the close valve. If you actually have a level transmitter you could totally automate using low level and turn on the open valve and shut off on high level.  You may have already known all this and I just missed it completely - if so, sorry.