What is a (PLC) programmable logic controller?
In its most simplistic form, a PLC can be likened to the conductor of an orchestra with all manner of instruments – woodwind, strings, percussion and brass – to coordinate into a cohesive concerto of sound. It’s the conductor’s job to trigger each section of the orchestra into action at precise moments in order for that concerto to make harmonic sense.
Replace the conductor with a PLC and the orchestra with a bunch of machines on a production line and the basic principle is the same. A PLC makes sure each of those machines jumps into action at the right time in order to produce a fully automated and highly precise end product. PLCs are basically digital devices containing pre-programmed memory designed to issue instructions to a suite of machines in a synchronized manner over and over.
What are the types of programmable logic controllers?
- Compact PLC. Compact PLCs are complete systems in a single, compact case. While limited, they can be a good option for smaller operations where the number and types of inputs and outputs are fairly standard and can be preset by a manufacturer.
- Modular PLC. A step up from compact PLCs, modular PLCs offer more versatility in size power levels and overall capability in a single rack.
- Small, medium and large PLC options. Built to suit everything from small businesses to heavy industry, these PLCs generally come with central processing unity, an input and output section, a power supply and either rack or mounted options. They can also be customized to suit specific processes.
What programs do programmable logic controllers use?
A PLC will use either an operating system or a user program.
- An operating system runs automatically and doesn’t need any direct operator commands to run systems.
- A user program allows an operator much more hands-on control of outputs.
What must be considered when choosing a PLC?
- How large is your operation?
- How complex is your operation?
- Does the complexity of your processes call for a smaller, more standard PLC case?
- Does the complexity of your processes call for a large unit with more versatility and power?
- Do you prefer a fully automated operating system or a more operator-driven user program?
How much does a programmable logic controller cost?
The cheapest is about $100 and the most expensive is around $570, but the average price for a programmable logic controller is a little over $280.
What are common problems with a programmable logic controller?
Without due care and attention, programmable logic controllers can become spectacularly illogical. The good news is that assessing any issues with a digitally intelligent device like a PLC is a lot easier than troubleshooting a tractor.
These are the main things that cause issues in PLCs:
- Input or output failure.
- Electrical noise interference.
- Corrupted memory.
- Power issues.
- Communication issues.
What type of maintenance does a programmable logic controller require?
PLC maintenance is ongoing and essential to ensure smooth operation and no production-killing hiccups.
- Maintain your PLC’s working environment. That means keeping temperature and humidity levels within the ideal range for your PLC.
- Keep the area dust free.
- Keep the PLC unit and circuit boards free of dust and debris.
- Clean all enclosure filters and replace if necessary.
- Check all connections for potentially damaging looseness and tighten if needed.
- Check I/O devices are correctly adjusted.
- Check LED battery indicators. Replace batteries if necessary.