PRTG Manual: MQTT Subscribe Custom Sensor
The MQTT Subscribe Custom sensor subscribes to a Message Queue Telemetry Transport (MQTT) topic and monitors up to ten numeric values from the received JavaScript Object Notation (JSON) data.
For a detailed list and descriptions of the channels that this sensor can show, see section Channel List.
- Dutch: MQTT Abonneren Aangepast
- French: MQTT abonnement personnalisé
- German: MQTT Subscribe (Benutzerdefiniert)
- Japanese: MQTT サブスクライブカスタム
- Portuguese: Assinatura customizada MQTT
- Russian: Пользовательская подписка MQTT
- Simplified Chinese: MQTT 订阅自定义
- Spanish: Suscriptor MQTT personalizado
Consider the following remarks and requirements for this sensor:
Remark |
Description |
---|---|
Credentials |
This sensor requires credentials for MQTT. |
IPv6 |
This sensor supports IPv6. |
Performance impact |
This sensor has a medium performance impact. |
Multi-platform probe |
You can add this sensor to a multi-platform probe. |
Setting |
Description |
---|---|
Channel #1 Name |
Enter a name for the channel. You can change this value later in the channel settings of this sensor. |
Channel #1 Unit |
Enter the unit for the numeric value that this sensor monitors. You can change this value later in the channel settings of this sensor. |
The sensor has the following default tags that are automatically predefined in the sensor's settings when you add the sensor:
- mqtt
- mqttsubscribecustom
For more information about basic sensor settings, see section Sensor Settings.
Setting |
Description |
---|---|
Topic |
Enter the topic that you want to monitor. The sensor supports single-level (+) and multi-level (#) wildcards. |
Time Since Last Message |
Select if you want to add a channel that shows the time in seconds since the last message was received:
You can define a threshold notification trigger to receive notifications if no data is received for a certain amount of time. |
Last Message Handling |
Define what PRTG does with the last message received if there are no new messages in the following scanning interval:
|
Sensor Message JSONPath |
Optionally enter the path to the value in the JSON data. The sensor shows the received value as the sensor message. The data must be in valid JSON format. For details about the format, see Channel #x JSONPath below. The sensor only shows the received value if the sensor is in the Up status. If the sensor changes to the Down status, the sensor message shows the error message instead. |
Channel #x JSONPath |
Enter the path to the numeric value in the received JSON structure that you want to monitor. The data must be in valid JSON format, for example like this:
{ To query temperature, enter the following JSONPath: $.Sensor1.Temp To query humidity, enter the following JSONPath: $.Sensor2.Humidity |
Channel #x Value Type |
Select the value type that the channel displays:
Absolute (integer) and Absolute (float) support the extraction of numerical values from a received string. The sensor parses the numerical value from the beginning of the string until it encounters the first element that is not part of a numerical value, for example a letter. The sensor ignores whitespace characters. You cannot change this value after sensor creation. |
Channel #2 - #10 |
You can define up to 10 channels. You must define at least one channel, so you see all available settings for Channel #1. Specify how to handle all other possible channels:
If you select Disable (default), you can still see the channels, but they do not receive data anymore. |
Setting |
Description |
---|---|
Primary Channel |
Select a channel from the list to define it as the primary channel. In the device tree, PRTG displays the last value of the primary channel below the sensor's name. The available options depend on what channels are available for this sensor. You can set a different primary channel later by clicking below a channel gauge on the sensor's Overview tab. |
Graph Type |
Define how this sensor shows different channels:
|
Stack Unit |
This setting is only visible if you select Stack channels on top of each other above. Select a unit from the list. PRTG stacks all channels with this unit on top of each other. By default, you cannot exclude single channels from stacking if they use the selected unit. However, there is an advanced procedure to do so. |
Setting |
Description |
---|---|
Result Handling |
Define what PRTG does with the sensor result:
This option is not available when the sensor runs on the hosted probe of a PRTG Hosted Monitor instance. In a cluster, PRTG stores the result in the PRTG data directory of the master node. |
By default, all of these settings are inherited from objects that are higher in the hierarchy. We recommend that you change them centrally in the root group settings if necessary. To change a setting for this object only, click under the corresponding setting name to disable the inheritance and to display its options.
For more information, see section Inheritance of Settings.
Which channels the sensor actually shows might depend on the target device, the available components, and the sensor setup.
Channel |
Description |
---|---|
Downtime |
In the channel table on the Overview tab, this channel never shows any values. PRTG uses this channel in graphs and reports to show the amount of time in which the sensor was in the Down status |
[Value] |
The returned numeric values in up to ten channels |
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