openhab-addons/bundles/org.openhab.binding.ntp/README.md

# NTP Binding

The NTP binding is used for displaying the local date and time based update from an NTP server.

## Supported Things

This binding supports one ThingType: ntp

## Discovery

Discovery is used to place one default item in the inbox as a convenient way to add a Thing for the local time.

## Binding Configuration

The binding has no configuration options, all configuration is done at Thing level.

## Thing Configuration

The thing has a few configuration options:

| Option          | Description                                                                                                                                                               |
| --------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| hostname        | The NTP server hostname, e.g. nl.pool.ntp.org                                                                                                                             |
| refreshInterval | Interval that new time updates are posted to the eventbus in seconds. Default is 60s.                                                                                     |
| refreshNtp      | Number of updates between querying the NTP server (e.g. with refreshinterval = 60 (seconds) and refreshNtp = 30 the NTP server is queried each half hour). Default is 30. |
| serverPort      | The port that the NTP server could use. Default is 123.                                                                                                                   |
| timeZone        | The configured timezone. Can be left blank for using the timezone defined as openHAB configuration setting (or default system timezone if not defined).                   |

## Channels

The ntp binding has two channels:

- `dateTime` which provides the data in a dateTime type
- `string` which provides the data in a string type. The string channel can be configured with the formatting of the date & time. This also allows proper representation of timezones other than the java machine default one.

See the [Java documentation](https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/util/Formatter.html) for the detailed information on the formatting

## Full Example

Things:

```java
ntp:ntp:demo  [ hostname="nl.pool.ntp.org", refreshInterval=60, refreshNtp=30 ]
```

Items:

```java
DateTime Date  "Date [%1$tA, %1$td.%1$tm.%1$tY %1$tH:%1$tM]"  { channel="ntp:ntp:demo:dateTime" }
```