1. Non-Blocking Code Blocks

In normal programming each code block must be executed completely before the next block is run. This means, for example, that you can only have one robot moving at a time. Sometimes, however, you want multiple robots to move together.

It's possible to do this using a special type of block called Non-Blocking (NB) blocks. With a "non-blocking" block, RoboBlocky will start the block's execution and then immediately move on to the next blocks in sequence while the non-blocking block continues executing. That is, the "non-blocking" block does not block execution of later blocks.

2. The driveDistanceNB Block

An example of a non-blocking block is the driveDistanceNB block:

3. The moveWait Block

We also use the moveWait block with non-blocking blocks to wait for all the non-blocking action to finish before ending the program:

The moveWait(); block will prevent the code from continuing until all of the non-blocking blocks before it have completely finished executing. Without the moveWait(); block the non-blocking blocks can sometimes have their executions cut short.
 

4. Turn Off Trace for Proper Operation

 IMPORTANT: When using non-blocking code blocks for moving multiple robots, it's often best to turn off the trace for the virtual robots on the screen. Leaving the trace on can cause lags in the operation of both the on-screen and hardware robots, especially when more than two robots are moving simultaneously. One way to turn off the trace is to use the trace on/off block (in the Robot menu):

You can also turn off the trace without having to use any blocks in the code. To do so open the Robot Settings section below the grid and uncheck the Trace Position checkbox:

For more info on turning the trace on and off, see this lesson.

5. The turnNB Block

The turn blocks are also available in non-blocking (NB) versions (see Example 4):

For more tips on using non-blocking blocks, see the lesson linked in the  More Info  button at top right.