HMI standard regarding symbol color

  • Thread starter Xander Houtenbos
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Thread Starter

Xander Houtenbos

During the design-phase of SCADA-applications there sometimes is confusion about the status of the symbols (e.g. valves, pumps etc.) and their color.
There is no HMI standard regarding symbol color that I am aware of. There does seem to be industry specific guidelines, however. Some industries like red to be the energized/on state, others use green for the same condition and so on.

Is there a HMI standard regarding symbol color or is there a report where the topic of symbol color is addressed?

Xander Houtenbos
 
>During the design-phase of SCADA-applications there sometimes
>is confusion about the status of the symbols (e.g. valves, pumps
>etc.) and their colour.

I have been in plants, large and small, with red for motor running, and as many others with green for motor running. This situation arose because of mainly historic reasons. I cannot believe that
this lack of consistency serves the public interest.

"Standards" that indicate colour based on hazard conditions lead to confusion - Is it hazardous because it is energized or hazardous because the operation is not normal?? What the operators really want to know is if the motor is running or not. To my knowledge, no standard with legal teeth across all industry groups put it simply
that a given colour indication applies to all energized motors, period. But then, can you imagine the resistance to change and unproductive expense that would be entailed to the non-conforming plants?

Standards aside, my own bias is green for running, on, or open. I appeal to no standard or convention; I just think this is more generally intuitive. This is especially true for valve position. Again, colour conventions for valve position tend to be industry and even plant specific. Plants which use green for motor running almost always use green for valve open. Some places which use red for motor running sometimes also use red for valve open and green for shut. This takes some getting used to. Other plants use red for motor running but still use green for "on" valves.

It seems especially difficult to apply standards which are framed in terms of hazardous condition to valve position. A valve can be energized to open, energized to close, energized on transition, safe when open, everyman for himself when open. It seems pretty clear that the MMI screen will be developed to show simply the open or closed position of the valve by colour. So the question is where is the universal standards chapter and verse that states the colour to be used for an open valve? I have found a lot more opinions as to what is stated in standards than actual definitive references to the point and in so many words.

Ron Sewell
Sigmatic Controls
Kelowna, B.C.
 
M
Lacking a standard (and ignoring the fact that red green color blindness is more common than you might think) I've found that the traffic signal analogy makes green for open or running and red for closed or stopped intuitive to the control
system operators.

Mark Erdle
Erdle & Boole
 
O
We have gone thru this debate also. One facility in which I worked, red was energized (i.e, something was flowing past this device, whether
it be gas, fluid, or electricity) and green was no flow. This was adopted so that there was consistency between the plumbers and electricians. :) In my current facility, we adopted something different, in fact we don't
even use green and red. If a device (breaker, valve, etc.) is the same color as the connecting pipe/line, then the device is allowing 'flow'. If
device is white, then there is no flow. It actually works pretty good. In our next system, we plan on making the pipes/connection change color as well as the valve to indicate 'flow'.
Orval Hart
Los Alamos Nat'l Lab
 
G

Glass, Philip

I've had a chance to view numerous HMI GUI displays built by various different people and I've built hundreds of graphical screens myself. I've found that what makes a GUI intuitive more than anything is consistency.

I saw an application recently where RED was the energized color because this represented danger and GREEN was the de-energized, safe color. The
programmer followed the convention that anything representing danger was RED. Apparently a basin mixer was considered dangerous if left off, so its energized color was GREEN while the pump feeding the basin was RED in its energized state because, hey, it's pumping chemicals.

As the great Yogi Berra might have proclaimed if he were a programmer "GUI design is half art, half science and half psychology".

You want your displays to be visually appealing, perform the desired function and be simple enough for the user to figure out without resorting
to a manual or proclaiming your status as a "Major League A.."-hmm.. just before calling you and saying "Could you please explain this PID faceplate to me?".

Everybody's used Microsoft products and say what you will about them, they are intuitive. Does anybody read the manuals after installing upgrades to figure out how to use new features? Most Microsoft products can be installed and run by the user without reading any books because the interface is intuitive and consistent.

I don't want to go into too much detail in this thread. Perhaps we should start a new thread on effective GUI design that would address GUI standards and conventions used in HMI development or VB applications or anywhere that a GUI is used.

To address the specific issue of color... Traffic FLOWS through the intersection when the light is GREEN. The light turns YELLOW and people
TRANSITION to a stop (Utopian society here, folks). When the light turns RED, traffic (in some cases) comes to a complete STOP. We live with this standard every day. Is this not intuitive?

Philip L. Glass
Computer Geek
Brown and Caldwell
[email protected]
 
A
On the SCADA and HMI's I have done the color is used and the words: on, off, open, closed, running, etc are used along with the color. The colors I have used has been set by the customer, because most industries has diffent standards they use and plants in diffent areas and countries are diffenet. I alwas try the match the color of the hardware light (lamp) with color on the computer screen (HMI).
Bob @
ALSTOM
 
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Ranjan Acharya

We try to use the following colour scheme unless the customer has his /her own standard:

- Red for fault or anything out of the ordinary. If the operator sees red anywhere on the screen it means they have to do something.

- Green for valve open or motor running.

- Grey for inactive (stopped, closed) or vessels, elbows, pipes et cetera.

Then of course there are colours for pipes -- steam, product, gases, .... which can be a real mess if there are lots of colours. Quite often the customer has labelled pipes in their facility so we try to use the colours there. Sometimes this is not possible -- a label is quite obviously bright blue or dark blue but a tiny pipe on the screen is not. Also some colours
are really quite difficult to see on a display.

Then of course there is colour blindness, which is very difficult to handle.

We try to go for a very clean screen. If the trackball / mouse pointer is hovered over an object then the pop-up tool tip will indicate the objects name and perhaps provide a small amount of information. If the mouse button is pressed to select the object then an ActiveX control (or something like that) handles the operator manipulating the object.

RJ
 
K
This issue... of different colors, different wire color, pushbutton naming convention, print numbering schemes etc etc. is the main reason why I insist on creating a "Project Dictionary" as a very early step in any development project. Every possible variable along the lines mentioned above such as wire colors, HMI colors, error messages, wire numbering schemes and so on are figured out in the dictionary before the project gets to far along... saves a lot of hassle.

Best Regards... Rick Kelly

Chief Technician
Natural Cuts
Cheese Operations
Kraft Canada
(613) 537-8069 V
(613) 537-8057 F
[email protected]
http://trondata.on.ca
 
I've just completed a pumping application where colours where needed to indicate 5 "states" for each of 150 pumps.

We needed to indicate "ON", "OFF", "Fault", "Disabled" and "Lockout".

As a result,,,,,,,,
OFF is Yellow (steady)
ON is Green (steady)
FAULT is Purple (flashing)
DISABLED is Blue (steady)
LOCKOUT is Red (flashing)

Across the bottom of each screen is a row of coloured boxes with the actual words (On, Off,Fault, Disabled, Lockout) written inside each box.

In summary, I don't think it matters which colours you employ, only that users fully understand their meaning.

Mark Hill
Intelligent SCADA Solutions
[email protected]
 
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Dave Kuipers

In working with Human Factors Engineers (philosophers?) colors, symbols and status information has no standard, unless the customer has existing systems or standards. Each customer seems to have varying standards in the HMI area.
The HF folks always fall back on the traffic light logic since we all intuitively know that green means go, yellow means warning and red means stop. Using this convention for valve, pump and heater status works well, but the electrical power industry uses red to indicate breaker closed and green for breaker open status. Color blindness can be handled by including text status and alternate status symbol configuration to indicate states. Other conditions like "power available" can be shown as white, and "no power available" as gray. Interlock and permissive tree graphics work well on pumps, heaters and other devices with multiple conditions required to operate.
Unless experienced with HMI systems, most customers don't know what they want. Define an acceptable standard and be consistent. The challenge is in combining the display presentation to optimize the operations being performed on the system. Color standards can be taught, processes need to be optimized by good engineering design of device, alarm, trending and parameter navigation, layout and presentation. The Operations staff provides the Subject Matter Experts for the operations of the processes.
 
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R A Peterson

NFPA79 calls for the use of green for off, amber for on, and red for alarm. See para 13.

I have seen various stds used. The most common seems to be green for off and red for running in industrial plants, and vice versa in process applications.

Most seem to use red or flashing red for alarms.

I like the NFPA standard and unless directed otherwise have been using it.
 
D
>To address the specific issue of color... Traffic FLOWS through the
>intersection when the light is GREEN. The light turns YELLOW and
>people TRANSITION to a stop (Utopian society here, folks). When the
>light turns RED, traffic (in some cases) comes to a complete STOP. We
>live with this standard every day. Is this not intuitive?

No, not always. It depends on your perspective. If you are working in maintenance and about to open a pipe, and you look at the valve feeding the pipe and see a GREEN indicator, do you GO ahead and remove the plug and hurt yourself? The standard that I've always used for manual indicators is Green means de-energized (no-flow, safe for maintenance), Red means energized (flow, not safe). This is done for safety of the personnel that do the manual work. For HMI, maybe colors should be different, though I like the
idea of a previous email that valves with flow match the color of connected pipe and valves with no flow are white or something else.
 
R

R A Peterson

> This issue... of different colors, different wire color, pushbutton
> naming convention, print numbering schemes etc etc. is the main
> reason why I insist on creating a "Project Dictionary" as a very
> early step in any development project. Every possible variable
> along the lines mentioned above such as wire colors, HMI colors,
> error messages, wire numbering schemes and so on are figured
> out in the dictionary before the project gets to far along... saves a
> lot of hassle.

A great idea. Unfortunately, this document never seems to make its way to the poor guy drawing the screens.

I just drew about 30 screens a couple weeks ago. After I submitted it, the end user's engineer sent me their specs on color coding of elements on
graphic screens.

Of course EVERYTHING had to change colors. Not a single element was the same as I had drawn it.
 
P
Interesting point. I have always done HMIs that were written primarily for the operators, not the maintenance techs. And, most of that has been for process systems. The traffic light analogy is the one that I have usually used. So, the point may be that the HMI is in the eyes of the beholder- Operations? Maintenance? IE's or QA/QC? I guess that we have to take more than one user type into account when designing an HMI. I have also, over the years, almost always used text tags to suppliment the colors, and have changed piping colors to match product flow. Finally, one of the things that I have made a good deal of use of
in Wonderware- and miss in FIX- is the ability to add other objects to command pushbuttons and set visibility properties for command pushbuttons. Greying out pushbuttons, or adding tiny "LED" lights to pushbuttons also helps to clear up some of these issues.

Paul T
 
D

Dave Ferguson

There are HMI standards defined by ISA. I am not at work but I am sure you can find them at http://www.isa.org/ . There are 3 or 4 different standards on different aspects of HMI's.

Dave Ferguson
Blandin Paper Company
UPM-Kymmene
DAVCO Automation
 
M
Ron,
On the SCADA system we are designing, the philosophy used is that colour is used for information. The state of the valve or motor is
reinforced by a status message. This was done to minimise operator mis information, especially as the degree to which operators were colour blind was unknown.

Regards
Martin Webb
 
B
Traffic flows across the intersection when the light is RED - so that is dangerous. Consider the pedestrian signal - cars are flowing so don't go.

I much prefer the Normal/Abnormal approach expounded here recently - Green = normal : Red = abnormal. To an electrician, "normal" = Bench or
de-energised, because that's the most likely way to see it and survive to tell the tale. To an operator, the plant is "normal" when it's doing
something in a safe manner and as per design.

Re changing colours on pipes - there are standards out there on paint colours to be applied to different pipelines to indicate the contents. Operators are usually well aware of this, at least the ones who have spent time walking around outside. It makes for a much easier transition to use this same colour code for lines on graphic displays. I don't think it is a good idea to change the whole line colour to indicate the presence or absence of flow.

And don't forget the rule about not indicating states you can't be sure of. A flow switch will verify flow - an oipen valve or a running pump
doesn't always. One of the problems at 3 Mile Island was that an indicating lamp was driven off the valve command signal rather than off a valve
position switch.

Bruce.
 
D

D Randall Iserman None

This is precisely why a set of maintenance screens should be prepared for each project. These screens give the maintenance crew the ability to select the instrument or equipment to take out of service. Once selected, the equipment and the associated piping is tagged as "In Maintenance" and keyed with a symbol and identifying color. The operators immediately see the changes on their screens and can monitor what is placed into Maintenance and when it is taken out of Maintenance. Depending on the client, the maintenance time is logged per machine or train.
 
M
> Traffic flows across the intersection when the light is RED
> - so that is
> dangerous. Consider the pedestrian signal - cars are flowing
> so don't go.
>
> I much prefer the Normal/Abnormal approach expounded here
> recently - Green
> = normal : Red = abnormal.

But if you have two pump, that if one is normally on, and the backup is normally off, then what?

> To an electrician, "normal" = Bench or
> de-energised, because that's the most likely way to see it
> and survive to
> tell the tale. To an operator, the plant is "normal" when it's doing
> something in a safe manner and as per design.

In many power houses, red means dangerous. If the switchgear is energized, it it dangerous. Since there may dual feeds, it shouldn't be assumed that the normal position is energized.
However, in other areas of the plant, green is used to indicate energized, which is the normal state for most devices, but not all.

Then, just to to make things fun, after the plants been using the system for 10 years, a new operator tells you that he is color blind, and can't tell the difference between red and green, so new scheme has to to picked, for at least on the systems that he operates. A one color scheme fits all is not always easy to find.

Mark Blunier
Any opinions expressed in this message are not necessarily those of the company.
 
G
> Interesting point. I have always done HMIs that were written
> primarily for the operators, not the maintenance techs. And, most of
> that has been for process systems.

I've developed interfaces for both maintenance techs and process operators.

Typically, the process operators I've worked with like green for things that go, move, can be switched ON. They also like things lit when they are "on" or "active" and dark when they are not. A good example is a dry materials handling system in which the bins, weighers and conveyor belts have onscreen "LEDs" that are dark green (unlit)
when the device is off, and bright green (lit) when a bin gate is open and feeding, or the conveyor is running. They like red to mark
emergency stop indicators, devices suffering control errors, and things that are down for maintenance or out of service.

Which brings us to the maintenance techs. Their big concern, as many have pointed out, is not putting anybody at risk to life or limb. There are several pieces of information to display about an object, and it would be dangerous to try to represent all of them with a single colored element.

To take an example from electric power substations, a breaker may be open or closed, hot or cold, locked out or not. The techs I've worked with like red for hot wires and green or black for cold wires. They use some standard symbols for the state of a breaker (solid box is closed, hollow box is open); we color the breaker
symbols according to state (red for closed, green for open), not power. (The rationale here is that an open breaker doesn't pass current, and a closed breaker might, whether the lines attached to it look cold or not.) We use a different color and shape combination to indicate a breaker in travel (solid yellow triangle) or that comm has failed and we don't actually know the state of the breaker (solid magenta circle).

Lockout/Tagout is represented with a separate visual component, a box or ring around the device. This mimics the long-time real-world
practice of hanging colored tags on control handles or locking selectors in place with color-coded locks. Since different companies have different color codings and different procedures,
we let them define whatever classes of tagout they require, including the color, the effect it has on the accessibility of the control, and the procedure for applying and clearing it.

All of which goes to illustrate a point. A process is a candidate for automation if we know how to do it manually. And most industrial
exercises have manual control conventions developed over a long period of time. These conventions have the positive attributes of being widely understood by operators and techs, and they have generally evolved as a function of experience. Computer systems that stick fairly close to the extant physical conventions - without
going so far as to mimic the limitations or aesthetics of physical control systems - tend to be well-understood by the people who use them, easy to train on, easy to use, and less subject to
accidental misuse.

Sorry to sound preachy; I think usable interface design is a big deal, and this is an issue that gets a lot of attention on our projects.

--
Greg Goodman
Chiron Consulting
[email protected] -- http://www.swbell.net/chironsw -- (713)
869-6876
 
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