Coding Standards

plcdog

Member
Join Date
Feb 2007
Location
Seaham
Posts
1
Hi

I am writing an internal coding standards document and I wondered if there were any individual manufacturers coding standard docs floating about in cyberspace that i could use as reference. For example, I read a Rockwell Coding Standard on RS View SE last year which had guidelines for VB, colour schemes and dynamic animation rules. Things like this would be very handy... If in fact they exist.
 
Coding standards are usually a unique company thing. For instance I used to work for a large food company, they had standards on PLC code and graphic displays.

Graphics standards included screen layout, plant colours, such as red=fault, green=running, etc.

Interfaces with the PLC, where each plant item had a standard bit layout for status and colour.

In the PLC suites if blocks existed for conveyors, valves etc, where 3rd party companies used these blocks.

I would say its best to look at what you have and pick the best aspects with some additions where you see fit.
 
Normally we think of green = running, red = fault, etc.

However, I've also run across systems that were exactly reverse of that. Red was running - red because the machine was not safe. Green indicated that the machine was safe because it wasn't running...
 
The Standard used to be Red for running, Green for stopped for the reasons you stated, however in the last 10/20 years the trend has been going the opposite, Green for running and red for stopped. Maybe Traffic lights are having an influence here.
 
Herm said:
The Standard used to be Red for running, Green for stopped for the reasons you stated, however in the last 10/20 years the trend has been going the opposite, Green for running and red for stopped. Maybe Traffic lights are having an influence here.

This conversation was had before on here when talking about lights. I've personally never come across a system which has red as running and I've been in this business since the late 70's.

As stated before though, standards for coding are specific normally to companies.

Someone who has only worked for one company and that companies standard is red for running might think its the norm and vice versa the other way round.

For thos of us who have worked for different companies over the years have seen numerous ways of coding, colour standards, wire numbering, plant ID, wire colours, etc.

I would presume with all that we've picked up we all have our favourite methods and standards but there's notr many actual standard.

I'm not a fan of forcing all companies to do the same, once that is forced on companies, the standard tends to get complicated as no-one agrees on anything and you end up with a mish mash of different standards trying to get everyone on board, the drawing standard that EU is trying to enforce is a testiment to that.

Although I do agree on a company having a standard, those that don't can end up a mess, but their standard should be tailored to their specific needs.
 
The last two companies I have worked for both used red for running and green for stopped. I always thought this odd but was told the same reason, red for danger green for safe. It has caused several problems with new operators but like all things, once you're used to it it's the norm.

I have seen a document on wiring colours while at college but again everywhere is different.
 
our company actually uses both. DOH

our units in the field are red running and green stopped.
our plant is red stopped and green running.
 
From NFPA79

10.3.2 Colors. Indicator lights and icons of color graphic interface devices shall be color-coded with respect to the condition (status) of the machine in accordance with Table 10.3.2. Alternate purposes shall be permitted to indicate machine or process status.Table 10.3.2. Machine Indicator Lights and Icons

RED Danger Emergency Faulty
YELLOW(AMBER) Warning/Caution Abnormal Abnormal
GREEN Safe Normal Normal
BLUE Mandatory action
CLEAR, WHITE, GRAY or BLACK No specific meaning assigned
10.3.3 Flashing Lights.
Flashing lights shall be permitted to be used for any of the following purposes:
(1) Attract attention
(2) Request immediate action
(3) Indicate a discrepancy between the command and actual states
(4) Indicate a change in process (flashing during transition)

 

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