PLC programming Spec

I have been assigned a task of writing up a PLC spec that will eventually be used as a standard anytime a project is started. This spec would outline a standard on how the code is initiated from beginning to end. I guess as you say it would have a systematic approach every time. Ie. how the data table is generated, when to use time base when not to use time base programming etc.

My question is has anyone here on this forum ever made up a standard similar to this? I am not sure how to start this. If someone has a sample document please contact me, it would be greatly appreciated. Thanks.

Do you use a specific PLC brand and/or model? When I was using an AB SLC we had defined which files were for what standard functions i.e. file 3 was communications, file 4 alarms, file 5 HMI, etc... If a project did not need this are it was just left blank. We also defined which bit file, integer files and such were associated with each file. So B11, C12, T13 and N14 may be with file 3. We also defined some bits and integers for things we use in every program so that the addresses and decriptions were consistent.

IF it is a tag based PLC you can define how file and tagnames are structure for consistency. You can create standard UDT's or add-on instructions.

I too would like to see a sample programming spec, specifically for A-B Clx and SLC500. TIA.

I created one some years ago & still stick to it, in short it stated that all symbols followed a specific structure i.e. BP01TK01M001Q for a motor output on a tank on a plant + depending on the type of plc a description in short form or if like AB a description field
Also insisted that the outputs were in a seperate block from sequence code & the structure was manual control ored with auto flags interlocked with the manual bit etc.
this way it is possible to see what auto bit should be turning the output on, any interlocks also go in this block (what might be holding it off & also by selecting the appropriate auto bit you could lnik to the sequence code to see why it's not being energised.
A good idea is also to use seperate auto flags for different sequences, this way you are not searching all over the place for a bit set/reset in 4-5 sequence blocks.

Fully commented and documented and in line with the drawings.

No password protection and full source code (with all comments etc) available.

That's a tough challenge. Every programmer thinks he/she is a free spirited artiste!!! They just don't like to conform to someone else's structure. Let us know how it works out.

Spec sheets

This idea keeps surfacing like the zombies of the living dead. As I have seen in minning and forestry, it is impossible to create a single formulae for programming. There are just too many individual processes. To cover all possible input devices and their corresponding applications plus considering how each device works in different contexts, the spec sheet would be too large and complicated to folow. I made very simple and very general guidelines, but even this was complicated and many pages long. Nothing beats a programmer who knows the process inside out and understands the technical limitations of the machines.