# Watch a fixture over time

- **MCP resource:** rdmbench://help/monitor
- **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

A report is one look at a fixture. Monitoring keeps asking and writes
down what changes, which catches the faults that need time or handling
to show. This topic watches one fixture. To find the unit on a line
that drops out, see [Watch the whole line](/help/monitor-line/);
to chase a fault that comes and goes, see
[Chase an intermittent fault](/help/intermittent/).

## Starting a session

Select the fixture and choose **Fixture → Start
Monitoring** (⌘M) *(macOS)*, or open the **Monitor**
tab and click **Start**. Before you start, the tab offers two choices:

- **This fixture** or **Whole line**: watch the selected fixture
  closely, or every fixture on the line for the one that drops out
  (see [Watch the whole line](/help/monitor-line/)).
- **Every**: how often to ask, from 1 to 15 seconds. 2 seconds suits
  most work. A longer interval suits a long soak test, where a change
  of a few seconds matters less.

Starting takes a fresh report first. That report is the **baseline**
each later reading is compared with, and it replaces the one on the
**Report** tab. Each round after that reads the sensors, the status
messages, the DMX start address and personality, and, where the
fixture keeps them, its counts of bad DMX and RDM frames. It does not
read the fixture's identity again.

Starting a session ends any other session that is running. **Stop**
(or **Fixture → Stop Monitoring**) ends it.

## Sensors

The left side lists every sensor: **Now** is the latest reading,
**Baseline** what it read at the start, and **Normal** the range the
fixture declares for it. The dot beside each turns orange or red when
the reading leaves its normal range.

Every sensor the fixture reports is read each round, so a slow climb
shows here before the fixture complains about it. To see how a unit
behaves warm, click **Put Under Load…** while it is monitored: the
fixture is lit for as long as you choose, the stretch is shaded on the
chart, and output ends by itself (see
[Load test a fixture](/help/load/)).

## Trends

**Trend** draws each sensor's readings since the start as a small line,
with its normal range shaded behind it. It shows the shape: a
temperature still climbing, or a fan that never speeds up as the unit
warms.

Under the table, the worst sensor right now is drawn large. Click
another row to draw that one instead. Time since the start runs along
the bottom, and each event is a line at the moment it happened: solid
when it is this sensor changing rating, dashed for anything else. A
status message that appears just as a curve bends shows up here as a
line at the bend. Where the fixture stopped answering, the curve has a
gap.

## Events

The right side is the list of what changed, newest at the bottom, each
with its time since the start (`+95s`) and a dot for how serious it
is:

- **A sensor changing rating**: `Head temperature: OK → WARNING`, with
  the reading that did it.
- **A status message appearing or clearing**, in the fixture's own
  words. A message that appears and clears again on its own is an
  intermittent fault, and the time beside each is the evidence.
- **The start address or personality changed**: someone changed it at
  the fixture's front panel during the session.
- **Device reported…**: a change the fixture announced on its own.
  Information only: when it is an address or personality edit, that
  change has its own event too.
- **Corrupt frames on DMX input** and **DMX512 packets with errors**:
  the fixture's own count of bad data rose since the last round. Only
  fixtures that keep these counts can show them.
- **Device stopped responding** and **device responding again**, and
  replies that came late or only when asked twice (see
  [Answered late or asked twice](/help/intermittent/#answered-late-or-asked-twice)).

The list says *No changes yet.* until something changes. On a healthy
fixture on a quiet bench, that can be the whole session.

## The summary

Stopping opens the **Session summary**: how many rounds over how long,
how many went **unanswered**, and, when there were any, how many came
back **late** or were **asked twice**. Then each sensor's lowest,
average, highest and last reading with its trend, every event, and under **Still
active** any status message that had not cleared when you stopped.
**Summary…** opens it again
until the next session starts.

Every session is kept in the bench's captures folder, one file per
fixture, written as it runs. A session cut short still has every round
up to that point.

## When an assistant is watching

An AI assistant connected to the bench can watch a fixture too, using
this same session. The Monitor tab says *An assistant is watching this
fixture* while it does, and the fixture's sidebar row gets a sparkles
badge. Click **Start** to take the session over and follow it here.
The assistant's watch ends where it stood.

## From the command line

`rdmbench-cli monitor` watches the first fixture found, or the one
whose UID you give it. It prints each event as it happens and the
summary when you press Ctrl-C. `--interval` sets the seconds between
rounds, and `--duration` stops it after that many seconds. `--json`
prints each round's events as a line of JSON, then the summary. The
session is saved to the same captures folder the app uses.