The Indicator Button looks just like a regular Pushbutton Switch – the difference is the
Indicator buttons display is controlled by a second TAG.
For example – when I press the regular pushbutton, it changes its TAG – this PUSHBUTTON TAG
at C100 to ON - AND shows that the button as changed to ON.
When I press the Indicator button however, its TAG at the PLC changes, this OVEN TAG
here, but the button didn’t change - Why not?
That’s because the Indicator button uses TWO TAGs.
One TAG gets the results of the button press – you can see that here when I change the
Indicator button from - the other TAG – the OVEN INDICATOR TAG in this example - enables
the buttons indicator.
So if I pretend I am the PLC, and I change this TAG … sure enough the indicator on
this OVEN button changed.
I’ll manually change it here a few times so you can see the indicator responds accordingly
– but note that it is NOT changing the status of the OVEN TAG.
This is a great thing to use when you want to be sure that the data got to the PLC.
For example: You press the button – that changes the TAG down at the PLC to ON – which
we are simulating here, of course - , then the PLC then sets the Indicator TAG (I’ll
pretend I am the PLC and flip this) to confirm receipt of the data and then the Button Indicator
finally changes state – you can see if I change it a couple times the button changes.
So again, this TAG controls the indicator, the other tag receives the results of the
button press.
This gives you a closed loop system where the user doesn’t get an indication that
the data was successfully received UNTIL the PLC says so.
With a normal button, when you push that button, you just have to assume the data got there
… Let’s see how to set up an Indicator button.
Double click or drag the indicator button onto the screen.
Don’t forget that you can also drag one of these pre-set button onto the screen to
if you see one you like.
It really is identical to the push button we did in a previous video, except here we
select a TAG for the Switch – which is that OVEN TAG – and here we choose the TAG that
the PLC will use to control the indicator.
Let’s enable a label here .. we’ll use our OVEN label … and don’t forget you
can always test your object by pressing the simulate button any time you want … you’ll
see the results both here in the simulator and on the screen.
Press OK, Simulate, save the project.
And up pops our simulator with our new indicator button.
As you can see pressing the switch doesn’t change the display, but it DOES change the
TAG down at the simulated PLC.
Now the PLC has to change the indicator TAG to turn the indicator on the button.
You could even have the PLC animate the indicator by blinking the button several times to indicate
action is required or use it to provide some kind of diagnostic code … use your imagination!
What happens if we specify the same Tag for both the switch and the indicator?
Let’s try that.
Double click on the switch, and I’m going to change the indicator TAG to be the same
as the switch TAG – so both of them are OVEN now.
Say OK, Simulate it … Example: Simulate.
Save the project and up pops our simulator.
Now our control window only shows the one TAG we are using on the screen .. and when
you press that button to change the TAG, the indicator button is also watching that TAG
so it instantly changes the indicator.
Now it acts EXACTLY like a regular pushbutton switch.
That’s it for this video – be sure to check out all of the other videos in this
series.
And as always, please send us any topics you would like to see covered – or - any other
comments for that matter – we appreciate the feedback!