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Sourcing the Equipment - Twelve Drummers

Eventually a suitable programmable unit (“the brains”) was acquired, an old industrial computer, known as a Programmable Logic Controller (“PLC” for short), now made redundant after about 15 years of 24/7 active service, but still in good working order. Yes, even working computers get made redundant these days!

This PLC would be able to hold all the “actions” in a sequential program and switch relays on and off as required.

Relays were necessary to switch the light elements on and off as the PLC outputs had only a low voltage capability (24v) and could not switch “Mains” equipment directly . These “interposing relays” were to be used between the PLC outputs and the 230V AC rope lighting elements to do the on/off switching as directed by the PLC’s program.

 

 

Once all the other parts (relays, bases, protective units, power supplies, cable etc., and also a large weatherproof box to put it all in) were ordered and received, “the build” could begin.

However, a month had now slipped by, and there were only four weeks left to accomplish assembly, wiring, PLC programming, test/debugging, and finally installing onsite, so it would need to be “full steam ahead” from now on if the deadline was to be met. Picture 5 – The PLC controller, a miniature relay and relay in base
Picture 5 – The PLC controller, a miniature relay and relay in base

Contributions by GordonG

TitleUpdatedType
Installing Onsite - Twelve Drummers 11 years 35 weeks agoBook page
Final Fitting - Twelve Drummers 11 years 35 weeks agoBook page
Wiring the Components - Twelve Drummers 11 years 36 weeks agoBook page
Backplate Assembly - Twelve Drummers 11 years 36 weeks agoBook page
Sourcing the Equipment - Twelve Drummers 11 years 36 weeks agoBook page
Unit Design - Twelve Drummers 11 years 36 weeks agoBook page
Design & Equipment - Twelve Drummers 11 years 36 weeks agoBook page
First Impressions - Twelve Drummers 11 years 36 weeks agoBook page
The Call to Arms! - Twelve Drummers 11 years 36 weeks agoBook page
Program Chart - Twelve Drummers 11 years 36 weeks agoBook page
Bringing the Display to Life - Twelve Drummers 11 years 36 weeks agoBook page
Programming the PLC - Twelve Drummers 11 years 36 weeks agoBook page