Logs

Follow the values of channels as lines of text while they arrive.

A log shows each new value of its channels as one line of text. Use a log to follow operator notes, the states of an automation, and slow sensors. A log can show channels of any data type, including text and JSON.

When a log opens, it shows the last 10,000 stored values of each channel, then each new value. A virtual channel stores no values, so its log shows only values that arrive while the log is open.

Create a log

Click in the tab bar, or press Ctrl+T (Cmd+T on macOS).
Select Log.
Click Configure channels, then click Add channel and select a channel.

You can also run the “Create log” command from the command palette. In the channels toolbar, double-click a virtual channel to open it in a log.

Add channels

Press V to open the component toolbar, then select the Channels tab.
Click Add channel and select a channel.
Optional: set an Alias to show in place of the channel name, and a color.

A number channel also has Notation and Precision settings. A timestamp channel has a timestamp format and a Time zone. To remove a channel and its lines, click Remove channel.

Pause and copy lines

Click (Pause scrolling) or press H to stop the log from scrolling. New lines still arrive. Scroll up to pause too. To resume, click or scroll back to the newest line.

Scroll up to see older lines. When you get near the oldest line, the log reads older stored values.

To copy lines, drag across them, or press Ctrl+A (Cmd+A on macOS) to select all. Then press Ctrl+C, or right-click and select Copy.

Set what each line shows

On the Properties tab of the component toolbar:

Field	Default	Description
Show timestamps	On	Shows the time of day of the sample.
Timestamp precision	0	The number of decimal places of the seconds, from 0 to 3.
Time zone	Local	The time zone of the line times, day rows, and copied dates.
Show channel names	On	Shows the channel name, or its alias, before the value.

The timestamp is the time of the sample from the channel’s index. Lines show in the order of these times, across all channels. A virtual channel has no index, so its lines show the time that the Console received the value.

A row with the date, such as Wed, Nov 4, 2026, shows above the first line of each day, and the top of the log always shows the day of the lines below it. Copied lines start with the date as YYYY-MM-DD.

Limits

A log holds up to 100,000 lines at a time, and it reads others as you scroll, so you can reach every stored value. The scrollbar shows your place in time across all stored values. A log of only virtual channels shows your place in the lines held.
A virtual channel stores no values, so its removed lines do not come back.
Select all covers only the lines held, not every stored value.
On an HTTP address, the browser Console copies plain text, and the browser can refuse a very large copy. The Console then shows an error.
A value with more than one line of text shows as several lines.
A value wider than the log wraps. Copied lines stay in one piece.

Troubleshooting

The log says “No data received yet”

Cause: The channels have no stored values, and nothing has written to them since the log opened.
Fix: Check that a task, a script, or an Arc automation writes to the channels.

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