Chapter 3

1. What is the difference between a compiler and an interpreter?

   A compiler will translate the code base all at one time and find errors before the program can run. An interpreter will translate a program line-by-line.

2. What is IEC 61131-3?

   A standard that governs the programming languages for compliant PLCs.

3. What is a machine instruction?

   Typically defined as an instruction that a family of CPUs use to carry out tasks.

4. What is a programming paradigm?

   A way in which code is architected and implemented. Examples are object-oriented, procedural, and so on.

5. Does IEC 61131-3 support OOP?

   Yes.

6. What is OOP?

   Object-Oriented Programming.

7. Is IEC 61131-3-compliant code always portable between devices?

   No.

8. Write an algorithm for withdrawing $20 from an ATM.
   1. Enter credit card
   2. Enter pin number
   3. Press withdraw button
   4. Input $20
   5. Take money from ATM
   6. Put money in wallet
   7. Walk off
9. What is a language translator?

   A program that translates human-readable code into machine readable...