Odometer card

Who it’s for

Anyone whose number only ever goes one way. A maintenance planner watching running hours tick toward the next service, a fleet operator reading distance, a plant counting units produced since the line was commissioned, an energy manager showing the meter total on a screen in reception. The number itself is not news on any given day; what people want is to see it move, and to recognize a counter the moment they walk past it.

What it does

A pump at 008427.3 hours: six drums for the whole hours and one for the tenths, turning behind a dark housing with the tenths on the opposite color, exactly as the meter on the wall is built. When the tenths pass nine the drum carries forwards into a zero rather than spinning back through eight, which is the detail that makes a counter look like a counter rather than a number being replaced.

• Turns a running total into something that reads from across a room, where a plain value card reads as text to be stopped and parsed.
• Keeps the width fixed. A set number of digits with the leading zeros kept means 427 stands as 000427 and the card never reflows as the total grows into it.
• Carries the way the real thing carries, and borrows backwards when a total is corrected downwards, which is the only time a counter should ever run back.
• Comes in two styles from the same two colors: mechanical drums for a dashboard with some character, and flat digits for one without. The roll is the same in both — it is the roll, not the housing, that says odometer.
• Wraps round when the total outgrows the housing, as a mechanical counter does, so six drums at 999999 roll to 000000 rather than widening the card.
• Shows one running total. It does not add keys together or compute the total from a rate, so a counter that has to be derived belongs in a calculated field first.

How to set up

The widget takes one entity and one numeric key, and reads its latest value.

Data keys

• One numeric key — Timeseries or Attribute. The total the drums show, taken as the latest value rather than over a time window, which is why the dashboard time window does not change what it reads. Its decimals decide how many drums carry the fraction and its units are printed beside the housing. A reading that is not a number, or a key with nothing on it yet, shows the no-data message instead of standing at zero, because a counter reading zero is a claim.

Counter

• Style — Mechanical by default. Mechanical builds one housing with the drums curving away at the top and bottom and the tenths on the opposite color. Digital keeps the rolling and throws away the machinery, setting the numerals straight on the card with the decimal smaller and softer.
• Number of digits — 6 by default. How many digit positions stand before the decimal, which is how many drums the mechanical housing holds. Set it to zero to let the housing fit whatever the reading needs right now, at the cost of a card that changes width as the number grows.
• Keep the leading zeros — on by default, and shown once a digit count is set. Stands a reading of 427 as 000427, which is what a real counter does and what stops the digits sliding sideways. Off leaves the unused positions off the card.
• Separate the thousands — off by default. Puts a gap every three digits, which is easier to read and further from the look of a mechanical counter, which has no gaps at all.
• Animate the digits — on by default. Each digit rolls to its new value instead of being replaced. Turn it off on a wall of many cards, where the motion is noise rather than information.

How to customize

• To swap the classic dark drums for a light counter — set Drums and Digits. In the mechanical style Drums is the housing and the faces of the drums while Digits is the ink on them; in the digital style the same Drums color becomes the ink and Digits is what sits on the decimal. One pair of colors covers both styles, so changing style does not mean reconfiguring the palette.
• To stop the card naming its own key — turn off Show the key label, which is worth doing when the widget title already says what is being counted.
• To drop the units — turn off Show the units. They come from the data key.

Tips

• Give the housing a couple more digits than the total needs today. A counter that wraps is authentic but rarely what anybody wants from their service hours.
• Point it at a key that only climbs. A value that goes up and down will roll both ways, which works, but the form promises a total and the eye will read it as one.
• Use the mechanical style where the dashboard has some weight to it — a dark header, photographs, a plant schematic — and the digital one where everything else is flat. Both read the same number; they just belong to different rooms.
• Turn off the animation on a wall of twenty of these. One rolling counter draws the eye, twenty of them is a slot machine.