The bar graph object shows a TAG value filling up a column or a bar, like a thermometer.
. As the TAG value, right here – usually on
the PLC - changes – I’ll change this TAG to a 23 - The graph reflects the result by
filling up the bar.
You can even set a target line and have the graph change color when that target is exceeded.
This target is set to 75, so I’ll change this value to an 80 and sure enough the color
of the graph changed when I exceeded the target.
This is a simple, easy, intuitive way to display analog data like temperature , pressure, and
fluid or fill levels.
Lets see how to set this up.
Double click or drag the Bar Graph Object onto the screen – or if you see one you
like down here in the parts list window, you can drag that on to the screen and save yourself
some time setting things up.
If you want to set it up yourself, you can enable a label – which can be at the top
or the bottom, do the alignment, the font all the usual things … you can show the
dimensions, or not, - if you do show them you can specify where you want them to be
located, how many divisions and if you want tic numbers or not.
You can setup a target line to be a fixed value – well use 75 in our example - OR
you can have a TAG determine where that target line is … that way the PLC can set the target
line in real time as the process is running.
Now a target of 75 doesn’t make any sense in a range of 0 to 9999 so let’s change
this to 100.
Now we have a more appropriate graph.
You can see on our graph and on our simulator our range goes from zero to 100 and our target
line is set at 75.
If you do set a target line, then you have the option of doing a change pattern.
The fill pattern right now is specified to be BLACK – let’s make that this cross
hatched pattern and then when we cross our target value let’s make this change pattern
to be BLACK so it really catches the users eye.
You can set the style down here, fill up, fill down, fill from the left fill from the
right.
We’ll leave it with the fill up in our example.
And of course we’ll need a TAG.
Lets have this bar graph monitor our Temperature TAG.
Looks like we are good to go so let’s say OK, resize the graph so it fits on the screen
… simulate it, save the project … and up pops our simulator with our new bar graph.
So again, this bar graph is monitoring this temperature TAG and it looks like we set a
target line at 75.
So if we fill up our bar graph, lets say to 45 … we see our cross hatched pattern … if
the TAG gets set to a value that exceeds our target line – remember our target was at
75, so let’s say 76 – then the graph changes color to alert the user that something is
wrong.
The color version is the exact same thing, except we have a lot more control over target
line colors, and the colors we use for the fill and change patterns.
Lets have this bar graph change to red when we exceed the target line.
Say OK and see what happens.
Before we do that … let’s make this a little bit bigger so it is easier to see.
There we go.
Now, Simulate, Save the project.
Up pops our simulated version of the 4 inch panel.
It’s still the exact same thing … except a little more colorful.
Filling with BLACK early on … when we cross that target line the whole thing turns to
red to alert the user.
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!