Lesson 3 - Principles of Process Control SAQ

** Compare PLCs and PCs in regard to their process control. Which would you recommend for a small brewery? Would your recommendation be different for a large, complex, fully-automated brewery?

Response:

PLC (Programmable Logic Controller)

Advantages:

• • Fast scan time

  • Robust (not likely to breakdown or malfunction)

  • Innately secure against cyber attacks

  • Easily linked to inputs and outputs

  • Can control PID loops

  • Easy to service

Disadvantages:

• • Not suited to complex calculations

  • No convenient human machine interface built in

  • Low memory and data storage

  • Often a more expensive option

PC (Personal Computer)

Advantages:

• • Complex calculations are easily performed

  • Human machine interface is built-in

  • Memory and data storage is built-in

Disadvantages:

• • Slower scan time

  • Not robust

  • Vulnerable to cyber attacks, computer viruses, and other malicious software

  • Links to inputs and outputs can be more complex

  • Might not be able to manage PID loops, which could necessitate stand-alone controllers

Small breweries will benefit most from a PC based control system. The setup is generally cheaper and it provides adequate functionality. However, the system might not be able to handle some more high-end tasks, and is not as stable as a PLC system. A PLC will be more robust for a large, complex, fully-automated brewery.