<p>I am writing some G-code for my DIY 3D printer. From what I understand, <code>G4</code> is dwell and its expressed in milliseconds. So my extruder takes about 30 seconds to heat up. Do I just type </p>

<pre><code>G04 30000
</code></pre>

You are correct about needing to specify the dwell value in milliseconds. However, the RepRap Wiki indicates that you need to use the
```
Pn
```
argument, and not just an unadorned number as the argument to the command. To adapt the Wiki's own example, you will need to use:
```
```
G4 P30000
```
```
This should cause the firmware to dwell (pause) for 30 seconds.
RepRap Wiki: G4: Dwell