Which direction should a software Strip-Chart scroll


Thread Starter

Clifford Jones

We are working on a StripChart upgrade for our
PocketHMI software and can't seem to find a
common direction the data plotting should go.

What direction do most people want to see?
New data appearing on the left and scrolling
to the right or new data appearing on the right
and scrolling to the left?

What are your opinions?

Cliff Jones - Narly Software

James T. Wilson

I have always seen strip charts with the new data begining on the right and the old data scrolling to the left.

Hope that helps.

Tony Lane (Pro-face UK)

On our HMIs we have a trend graph feature to graph data on either a time or trigger basis. We start displaying from the left and grow the display to the right. Once the display window is full we scroll the graph to the left by a user selectable number of samples which could mean clearing the whole window and starting again or maybe just one sample so the window always shows a full page of samples.

We also have a Pen Chart mode which enters the data on the right and scrolls it to the left, but most of our customers don't use this.

The answer is therfore that there is no correct answer and whatever you do someone will want it done the other way. Then again these comments come from a country that drives on the left....

Hope this helps.

Tony Lane
Proface UK

Townsley, Bill


I know where you are coming from...I've seen it even within the same application where a trend scrolls to the right while a PID tuning chart
scrolls to the left.

My personal feeling is to have the new data appear on the right and scroll to the left. It seems more natural to read the history of the trend this way (probably because we read from left to right).

new data on the right, and scroll to the left. If this is for your PalmHMI package, how about bottom and scroll up?

--Joe Jansen

Francus, West (IndSys, GEFanuc, Albany)

why not just add a "flip direction" button or option? everybody's happy...


C. Ward Yelverton

yes ... absolutely it should be one ... or the other.

Doubt that you'll ever get agreement on this issue, depends on whether the person is used to an oscilloscope (say a Tektronix vacuum tube model where the sweep moves and the strip stays
still, equivalent to appearing on the right and scrolling to the left. Or conventional chart recording. Or X-Y, which could go either way. Heart monitor. Etc.

Bottom line is that both are common and probably half of your respondents are going to want the other one.

First thought ... there are many more important things to worry about. Second thought, is it that difficult to have this a user option? Know you're squeezing code size, but you've already got the other problem of is UP positive or negative? That's another optional setup
parameter dependent on the particular measurement.

Glass, Philip

Time lines traditionally always show most recent time at the right. If you look at other charts like seismographs, polygraphs and even heart monitors, you'll typically find right-to-left data. As long as you display time on the X-axis, I don't think direction is even relevant. I instinctively look at the right side of a chart for most recent data. Hope this helps.

Philip L. Glass
Computer geek
Brown and Caldwell
[email protected]

Robert Dusza


We use new data appearing on the right and scrolling to the left. This is how our manual strip charts worked on the past. Just what you are used to.

Hope this helps.

Robert J. Dusza, Jr.
Treatment Manager
(V) 1-860-647-3219
(F) 1-860-647-3150
E-mail - [email protected]
Manchester Water & Sewer Dept.
125 Spring St. P.O. Box 191
Manchester, CT 06045-0191

Rich Anderson

I prefer to see the strip as a "time line". With the past to the left, and the present to the right. I guess this would be "new data
appearing on the right and scrolling to the left"

That's my vote.

Rich Anderson
Automation Controls Programmer
Anamax Group

Anthony Kerstens

Given that I normally presume the y-axis to be time, and expect that zero is at the left, then I would say that new data should be on the right and old data should scroll from right to left.

Anthony Kerstens P.Eng.
I have found that most people want the time to increase from left to right. This is the way time domain data is plotted in all math and science textbooks from grade school on up.

Jay Kirsch
Macro Automatics
2985 E. Hillcrest Drive, Ste 101
Thousand Oaks, CA 91362
[email protected]
Considering oscilloscopes and logic analyzers go left->right with the passing of time, I would bring in new data on the right, scrolling the old data to the left.

(consider a stock ticker scroll...)

(How would you want the data to look if you did a freeze-frame? Or ripped off a piece of strip chart?)

I can't remember ever seeing a device that plotted recent data on the left with older data to the right. But I'm not in a process industry that uses a lot of that type of data. I'm curious to hear about one now.


Tanweer Ahmed

I believe in this graph plot X-axis is time which will always increase and never go negative. That means your chart will be in 1st and 4th
quadrant. Therefore it will be new data appearing on the right and scrolling to the left. This is the most common practice in HMIs.


Tanweer Ahmed
Phone: +9221-636 5519
Fax: +9221-568 2972
E-mail: [email protected]

Clifford Jones

Regarding the pocketHMI Strip Chart,

It looks like the group agrees on the direction of the time axis. Meaning, the most recent data on the right, the oldest data on the left. This is if we are charting horizontally.

The Idea of scrolling from the bottom to the top is intriguing. That is something to keep in mind (Maybe for equipment running reverse / forward).

The "Pen Chart" mode is really what we see on a piece of paper but on a Palm Pilot screen starting plotting on the left and when the display is full scrolling to the left seems to make the most sense. Kind of like driving on the left in some countries{Grin}.

Thanks to all for the input.

Cliff Jones - Narly Software

Ranjan Acharya

Kind of like driving on the left in some countries{Grin}.

The Greeks and Romans (purportedly) drove on the left. As did everyone else in a higgledy piggldey manner.

Napoleon sent his troops on the far right of the road so as to provide an effective parallel path to slower-moving local traffic.

I don't know how much of the above is true, but that is supposedly the reason why countries without Napoleonic influence still drive on the left (UK, Commonwealth, Japan ...) or used to drive on the left (Scandinavia).