Baud rate mismatch

You see

You connected, but the Console panel shows:

• Random characters where the GRBL welcome message should be.
• Nothing at all.
• Partial readable messages mixed with garbage.

What is happening

Serial communication requires both ends to agree on the data rate (baud rate). When they disagree, bits are misaligned and you see garbage. Most GRBL controllers default to 115200, but some older or custom builds use 9600.

Fix

If you do not know your machine's baud

Try these in order:

1. 115200 (most common GRBL default).
2. 9600 (older or custom).
3. 57600 or 38400 (rare).

In Device Settings → Connection:

• Disconnect.
• Change Baud Rate.
• Reconnect.

Repeat until the Console shows a clean welcome message like Grbl 1.1h ['$' for help].

If your machine documentation specifies a baud

Use that. If the docs say one thing but the firmware was rebuilt, the firmware wins, try other baud rates until you find one that works.

If only the welcome message is garbled but commands work

A timing issue at startup. Not a real mismatch. Verify by sending $$, if the response is clean, the baud is right.

If garbage persists at every baud

Something else is wrong:

• The USB cable is bad (replace).
• The controller is faulty.
• The driver is mismatched (Windows).

See Machine will not connect.

Verify it worked

• Console shows the GRBL welcome message cleanly on connect.
• Sending $$ returns a clean dump of $ settings.
• Status queries (?) return clean status reports.

Still stuck?

• Console panel: keep this open while testing baud rates.
• Connection Diagnostics panel: TX/RX hex view shows whether bytes are coming through at all.
• Baud rate and serial port guide.