# Connect the widget and find the fixture

- **MCP resource:** rdmbench://help/connect
- **Version:** 0.2.0
- **Runs on:** macOS 15 Sequoia or later, Apple silicon or Intel
- **Needs:** An Enttec DMX USB Pro with its DMX/RDM firmware (major version 2)
- **Price:** Free

The bench talks to a fixture through an Enttec DMX USB Pro, called the
widget here: USB on one side, a DMX line on the other. Connecting opens
the widget, then searches the line for every fixture that answers RDM.
The first one found is selected and its report is taken.

## Before you connect

The widget needs its *DMX/RDM* firmware, the fixture needs RDM switched
on, and a terminator belongs in the fixture's DMX output. If connecting
fails or nothing is found, see
[When no fixture is found](/help/no-fixtures/).

## Picking the port

Choose **Fixture → Connect…** (⌘K) *(macOS)*. The
sheet lists the serial ports this computer has. Ports that look like the
widget come first, marked *likely widget*, and the first of them is
selected. Each row shows the widget's name and serial number, and under
it the device path (`/dev/cu.usbserial-…`) *(macOS)* / (`COM3`, for example) *(Windows)* / (`/dev/ttyUSB0`, for example) *(Linux)*,
which is what the command line takes.

Every other port is under **Show all ports**. An adapter cable that
does not look like an Enttec widget ends up there, so try that list
before deciding the widget is missing. If you plugged the widget in
after opening the sheet, click **Refresh**.

**Connect** opens the selected port. **Use Simulator** connects to
simulated fixtures instead, so you can learn the app with no hardware.

The checkbox on the sheet lets the bench check for a newer
manufacturer PID library when you connect: one request to github.com,
with nothing about your fixtures sent. With it off, or with no network,
the bench works the same with the library it has.

## Finding the fixture

Connecting runs discovery: the bench searches the line and lists every
fixture that answers in the sidebar. The status line at the foot of
the sidebar says what it is connected to. Run it again with
**Fixture → Rediscover** (⌘R) *(macOS)* after plugging in another
fixture or changing a cable.

If the sidebar says *No fixtures found*, or a unit appears under
**Could not be listed**, see
[When no fixture is found](/help/no-fixtures/).

Under **Line**, the bench compares this discovery with the last time it
looked at a line: a unit missing since then, or a new one that has
arrived. At a bench the last look was usually the previous job, so
these are notes, not faults. Once every unit has a report
(**Fixture → Scan All Fixtures**), the same section says what is wrong
between them, such as two fixtures on overlapping addresses.

**Fixture → Disconnect** turns off identify on any fixture that is
identifying and releases any levels the bench was holding, so nothing
is left flashing or lit on the bench.

## From the command line

`rdmbench-cli ports` lists the serial ports, with a `*` beside those
that look like the widget. `rdmbench-cli discover` searches the line
and prints the UID of each fixture found. It picks the first widget it finds; `--port`
names one, and `--sim` uses the simulator.

Once a fixture is found, see
[Read a fixture's report](/help/report/).