Guidance on project modelling / description

treaney

Member
Join Date
Jun 2008
Location
Claremorris
Posts
5
I'm starting a new PLC control project and would appreciate some guidance on how to do things right.

I need to model/describe what is it that I need the machine to do. I am familiar with the waterfall model of software development(from Wikipedia):
  1. Requirements specification
  2. Design
  3. Construction (AKA implementation or coding)
  4. Integration
  5. Testing and debugging (AKA Verification)
  6. Installation
  7. Maintenance
I can write it down and describe the functions. What I want to ensure is that I'm using an industry standard representation. I can do a flowchart by hand but would prefer to do this with software. Any pointers as to where to find a template for an automated machine would be helpful. I'd love an Excel spreadsheet model to help with this.
 
Thanks Lancie - an impressive piece of work.

I'll send some time to figure it out. It will certainly help in what I am attempting to do.
 
Treaney,

You probably call them "lifts" over in Ireland.

Each cell of the Elevator spreadsheet was a rung on the original relay ladder logic schematic drawing of the elevator. The schematic drawing (and the actual elevator) was all I had to work with in making the simulator spreadsheet.
 
Last edited:
We do indeed call them "Lifts". Also lifts go from the Ground floor to the First Floor to the Second Floor...

I'm still working on understanding your Elevator Excel spreadsheet.
 
I'm still working on understanding your Elevator Excel spreadsheet.
One important thing to know: Rung contacts in parallel (on separate rung branches) translate to Boolean "OR" statements in the Excel spreadsheet. Rung contacts in series translate to Boolean "AND" statements. Normally Open switch contacts on the schematic = Contact Name in the Excel spreadsheet, while Normally Closed contacts = NOT Contact Name.

Some time delays are created by applying a 1-second Macro delay for however many seconds delay is needed. Closing or opening the elevator door requires 5 seconds, so Macro routine A8-delay is run 5 times. The two physical timers T3 and T9 are simulated by adding 1 to a number in the cell below the timer, until a certain delay value is reached, 8 for T3, 9 for T9.

To operate the "lift", enter a "1" in one of the 12 floor pushbuttons (1 on each floor, 6 inside the car), then press the RUN pushbutton, or type Ctrl R to start the Macro. You can see the various relays switch from 0 to 1 as the door closes and the car moves. At the end of travel, the relays switch back to "0" or deenergized, and the door opens.
 
Last edited:
I will advise you if you can, to start looking for S88.
We are working now with that, and I can tell you this, it is very hard at the beginning, but when you understand it, its nice. You can live without it...
 

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