The Real Time Graph simply monitors TAGs – this example is setup to monitor a TAG at DS500
on a Click PLC and another TAG as DS501 on the same PLC– and displays it in a scrolling
right to left chart once a second..
I’ll pretend I’m the PLC and change the values.
Let’s change temperature to a 25 … temperature 2 to a 33 .. temperature 1 to a 55 .. temperature
2 to a 75 … temperature to a 99 … temperature 1 to an 11 .. and let’s send this guy right
off the chart to 200 … and then bring him back down to 22.
You can see what’s happening here – the data values scroll from right to left.
As soon as I update the values, the graph responds.
This graph is set to update once per second, but you can set that to anything you want.
Minutes, hours – even days.
This is an excellent way to keep an eye on historical trends – BUT be careful – this
is NOT a data logger.
You only see these data points as they scroll by.
. you can’t scroll back to review the history or retrieve any old data.
If you need true data logging functionality, take a look at the C-More Micros Big brother
– the regular C-More panels – they have data logging and a bunch of other high end
features.
Let’s see how to set up a real time graph.
Double click or drag the real time graph onto the screen.
In the black and white version of the panel, you can create two plots per graph by assigning
TAGs to “pens”.
Click on the PEN tab … and assign TAGs to each of the pens.
We’ll use our Temperature and Temperature 2 TAGs in this example.
Back in the General Tab, you can specify the number of points per plot, up to 24 right
here.
When you do that, things get real crowded on the graph so I like to turn off a lot of
features just to clean up the plot.
Let’s turn off the X-Axis label and grid to help clean up the graph make more room
for the X-Axis.
. Note that the graph on the display and in the mini simulator window both give you an
instant preview of what it is going to look like.
Let’s also turn off the Y-Axis label.
Remember – you can always add static text next to the graph to label it later.
You don’t have to use precious plot area to do that.
Let’s set our refresh interval to 1 per second and say OK.
We want to move our plot onto the screen … let’s just take up the whole screen with this so
we can see it … click Simulate, save the project … and up pops our simulator with
our new graph.
Now the Graph IS running right now, we just can’t see the results because the temperature
values are both zero.
Let’s add some values here – I’ll put 25 for Temperature 1, and 33 for temperature
2 and then maybe temperature 1 changes to 65, again, I’m just pretending I’m the
PLC here .. and a few more just so we can see.
There are two other options we need to look at: Dynamic Range and Triggers
Double click on the graph to bring up the dialog.
Click on the Dynamic Range check box to allow the PLC to take control of the min and max
limits of the plot.
Before we had a strict limit of 0 to 100 and if we had specified a temperature that was
200 it simply would have gone off the top of the graph.
But now with dynamic range, the PLC gets to specify what those min’s and max’s are.
We’ve already created some TAGs, let’s set the limit low here and limit high here.
So now the PLC can change the limits in real time as it is plotting the data.
Lets hit OK and see what happens, Simulate.
Save the project … and up pops our simulator.
Again, things are running right now, we just can’t see ‘em.
Lets go ahead and set temperature 1 at 75 .. that would be easy to see.
Let’s set Temperature 2 at 50.
No neither one is showing up on the graph – why is that?
We’ll that’s because the high limit is set to zero.
Let’s go ahead and set that high limit to 100.
And now all the sudden things appear exactly where we expect to see them.
Temperature 1 is at 75 and temperature 2 is a 50.
Now what if I change the high limit to 1000.
Well, it changes the scale of the graph and 75 and 50 look like really small numbers.
If I change temperature 1 up to 750, then it makes more sense.
So now the PLC is in control of scaling of the axis.
Note that with dynamic ranging, you can’t see the Y-Axis numbers – we didn’t turn
those off – they simply aren’t an option.
You COULD use a numeric display and have the PLC provide the axis values in real tie if
you want to … The last feature is triggering.
Let’s go back to our dialog – I’m going to turn off Dynamic Range so we don’t have
to fool with that.
Before we had specified a refresh interval of 1 per second.
You can also have the PLC be in charge of the refresh interval by specifying a TAG right
here.
We have a TAG called TRIGGER that we will use .. and you also have to specify what the
trigger condition is – is it when the Tag is OFF or ON?
Let’s say it is when it transitions from off to on.
Let’s try that.
We’ll Simulate the project .. save it, and here we are.
Let’s bump our temperature up to 75 for temperature 1 and how about 95 for temperature
2.
We’re not seeing anything on the graph – why not?
We’ll, because it hasn’t been updated yet.
The C-More Micro is watching this PLC TAG called Trigger, and waiting for it to transition
to an ON to update the display.
I’ll pretend I’m the PLC and do that here.
And once I trigger that the display gets updated.
So if we change the values again … once again, the values don’t get updated until
this TAG transitions from an OFF to an ON .. and there it is again.
One more time … Transition the TAG … and there’s the update.
So now the PLC is in control of how fast the display scrolls from right to left.
This is great when you want the graph to be updated only on certain events and not on
periodic intervals.
While we are here, let’s go ahead and flip over to a color example, because there are
a few advantages to using color here.
We’ll go to our navigation menu function tab … panel manger.. and we’ll flip this
up to a 4 inch color panel.
Adjust the screens?
Sure.
So it adjusted the graph to the full size of the 4 inch color screen.
We’ll double click on this and it is exactly the same thing as we had with the black and
white version … except now you have more color options for objects, for the text .. but
most importantly, you now have eight pens to play with.
Let’s take a look – we have two temperatures, lets add one more temperature … Temperature
3 .. We’ll say OK, simulate it, save the project.
There we go.
So we have our three temperatures that are being automatically updated, let’s put a
couple values in and see what happens.
And there is our real time color graph.
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!