Chapter 10

1. What is a function block?

   A digital blueprint that is equivalent to a class in a general-purpose programming language.

2. Can a function live in a function block?

   Technically, no. Methods which are equivalent to functions live in function blocks.

3. Do all PLC programming systems support function blocks?

   Generally, yes.

4. Name three common function blocks in CODESYS.
   • TON
   • TOF
   • CTU
5. Do all function blocks have the same inputs and outputs?

   No.

6. What is the main difference between a TON and a TOF timer?

   TON on hold a bit off for a given amount of time while a TOF will be on for a given amount of time.

7. What is the main difference between a timer and a counter?

   A counter will increment with a rising edge while a timer will toggle a bit after a give period of time.