Blocks

The VEX 123 Blocks API Reference explains what each VEXcode block does, how its inputs change the robot’s behavior, and how the block can be used in a project.

Use this reference when you want to understand a block before adding it to a project, check what a block reports, or compare similar blocks in a category.

How to Read a Block Entry

Most block entries include the following parts:

• Block description - Explains what the block does and when it is useful.

• Block image - Shows what the block looks like in VEXcode.

• Parameters - Lists the inputs on the block and explains how each input affects the robot or project.

• Return value - Explains what a Boolean or Reporter block reports.

• Example - Shows one way the block can be used in a project.

Common Block Types

Different blocks have different shapes and jobs in a project.

Block Type	What it means
Stack	A block that performs an action. Stack blocks connect above and below other blocks in a stack.
Hat	A block that starts a stack of blocks when something happens, such as when the project starts or an event occurs.
Boolean	A block that reports True or False. Boolean blocks are often used inside conditions, such as if or wait until blocks.
Reporter	A block that reports a value, such as a number or text. Reporter blocks are often used inside other blocks.
C block	A block that wraps around other blocks and controls when or how they run, such as repeating blocks or if then blocks.

Example Block Entry

drive

The drive stack block moves the robot forward or reverse forever. The robot will continue to move until it is given another action, like turning or stopping.

  drive [forward v]

Parameters	Description
direction	The direction the robot moves: forward or reverse.

Example

  when started
  [Drive for 2 seconds.]
  drive [forward v]
  wait (2) seconds
  stop driving