Its all right for maintenance to view screens for system component status, however I think the operators should place the equipment into a "maintenance lockout" condition. Maintenance should always work through the operations staff prior to doing work. I have implemented Maintenance Blocks into various HMI systems that allow the operator to log the work order, contact name, and tagout/lockout information to a device which in turn prevents any scada/control system control actions from being performed on the device and a "M" or other symbol is placed adjacent to the device and in control popup screens for the device clearly indicating the Maintenance status of the equipment. The operator is ultimately responsible for the system while it is in operational status and should be the one who places it in and out of service.

 

Regarding color blindness, our HMI is set up where a solid filled object means one thing, and a border object without any fill means another. Thus you can keep your standard colors for everybody, plus you can print your screen on a black and white printer.

 

How about those personnel who are color blind? Are they allowed to operate?

 

One of the entries in the "Project Dictionary" I mentioned earlier covers off the text to be superimposed on each and every HMI component. That way when a flashing red button appears to a color blind operator as something other then red, the text serves as a "color check" for the color blind operator.

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 designed a HMI for a Heavy Water Plant using Honeywell TPS with the following standards:

Pumps/Motors: RED: Faulty/YELLOW: ready to start/GREEN : running

ON/OFF Valves: RED: Faulty / MAGENTA: closed / GRAY: in transit
/GREEN: open

Automatic Valves: RED: Faulty / YELLOW : In Manual / GREEN : In
Automatic / CYAN: Cascaded


Hope this helps


Claudio A. Perez
DCS Engineer
Technical Department
PROFERTIL S.A.

 

A standard already exists!
NFPA 79 has all the colors for indicating lights on control panels.
These should also apply to HMI Screens.
I am sure that there are some exceptions, or applications that aren't covered very well by NFPA 79. In that case use common sense.


Gerry Moore

 

There is a standard out there today that has great guidlines and can help you design your SCADA application. The standard is the ISA.

ANSI/ISA-S5.5 1985 Graphic Symbols for Process Control.

 

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