PRTG Manual: Sensor Channels Settings

A sensor has one or more channels in which it handles the actual monitoring data. In the channel settings, you can define how to display the data from the sensor's different channels displayed in graphs, gauges, and tables. Additionally, the channel data can determine the sensor status. Use the limit settings to define desired sensor states for values.

On the sensor's Overview tab, click the gear icon of a specific channel gauge to change its settings. Click the pin symbol on the right of the gear icon in a gauge to make this channel the primary channel of the selected sensor.

You can also open the settings of a channel by clicking the gear icon in the channels data table.

icon-i-roundFor lookup channels, we recommend that you stay below 120 lookup values to get expressive gauges. For non-primary lookup channels, the upper limit is around 40 lookup values.

The Gear Icon of an SNMP Traffic Total Channel to Open Channel Settings

The Gear Icon of an SNMP Traffic Total Channel to Open Channel Settings

The available options are nearly the same for all sensor types. An exception applies to the Downtime channel, which is automatically calculated and does not offer all settings. Channels with absolute values additionally have an option to define the Value Mode.

You can quickly choose another channel of the selected sensor via the dropdown list at the top of the channel settings list.

Channel Settings for a Disk Sensor

Channel Settings for a Disk Sensor

Available Channel Settings

Edit Channel

Name

Enter a meaningful name to identify the channel (not editable for script sensors after sensor creation). The name will appear in graphs and tables.

icon-i-roundYou can automatically add the sensor's ID to the name by using the placeholder [#id].

Unit

This field is only visible for custom sensors. Enter a string that describes the unit of the returned values. This is for display purposes only. Please enter a string.

Scaling Multiplication

This field is only visible for channels with a custom unit. If you want to multiply the received raw data by a certain value, enter the multiplier here. Otherwise, use the default value 1 to not change the received value. Please enter an integer value.

icon-i-roundThe following sensor types provide the scaling factor for received values with custom units in their sensor settings.

Scaling Division

This field is only visible for channels with a custom unit. If you want to divide the received raw data by a certain value, enter the divisor here. Otherwise, use the default value 1 to not change the received value. Please enter an integer value.

icon-i-roundThe following sensor types provide the scaling factor for received values with custom units in their sensor settings.

Value Lookup

This field is only visible for custom sensors. Select the lookup file that you want to use with this channel.

icon-i-round-redDo not use this option for sensors that provide the unit Value Lookup in the sensor settings! This channel setting will be overwritten with the next sensor scan. Please define the lookup file that you want to use with this channel on the Settings tab of this sensor. Choose the option Value Lookup for the setting Sensor Channel #x Unit (where x is the number of the channel) and choose the desired lookup file under Sensor Channel #x Value Lookup.

icon-book-arrowsSee manual section Define Lookups—Requirement: Channel Unit "Custom" for affected sensor types.

ID

Shows the ID of the channel. You cannot change the ID. PRTG uses it for unique identification. For example, you need the ID when using Sensor Factory sensors.

There are a few special, fixed channel IDs.

  • -1 is for sum channels of traffic channels (for example, of the SNMP Traffic Sensor).
  • -4 is for the Downtime channel (you can use it, for example, for an uptime percentage calculation in a Sensor Factory Sensor).
  • -2 (coverage) and -3 (error) are internally used.

Graph Rendering

Define if you want to show this channel in data graphs. Choose between:

  • Show in Graphs: Sensor graphs contain the data of this channel.
  • Hide from Graphs: Sensor graphs do not contain data of this channel.
    icon-i-roundIf you choose to hide this channel in graphs, it also will not appear in a Report if you include this graph.

Table Rendering

Define if you want to show this channel in data tables. Choose between:

  • Show in Tables: Sensor data tables contain the data of this channel.
  • Hide from Tables: Sensor data tables do not contain the data of this channel. This option hides the channel gauge as well, but the channel will still be available in the data table of the sensor's Overview tab.

icon-i-roundIf you choose to hide this channel in data tables, PRTG also will not use it for the calculation of the "sum" (total) channel of a sensor.

Line Color

Define the color of the channel display in graphs. Choose between:

  • Automatic: PRTG sets the color of this channel in graphs automatically.
  • Manual: Individually define the color of this channel. You can enter the desired color code below.

Color (#rrggbb)

This option is only available if you choose manual line color above. Enter a color in hexadecimal RGB notation as in HTML and CSS, or choose a color from the visual color selector. The field with the hexadecimal color value will change to the selected color automatically.

Line Width

Define the width of the channel line in graphs. Enter an integer value in pixels. The maximum line width is 25 px, but we recommend that you use values between 1 and 7 only to get optimal results.

Data

This setting is available for most channels. Define how to display data. Choose between:

  • Display actual values in [unit]: Display the values in the shown unit.
  • Display in percent of maximum: Calculate and show percent values based on a maximum value. Provide a maximum below.
    icon-i-roundIf you choose this option, you cannot display the data of traffic sensors as a positive and negative area graph.

Maximum ([unit])

This field is only visible if you choose the percent of maximum setting above. Enter a value to use as maximum. Please consider the given unit. PRTG will calculate all percent values based on this value.

Please enter an integer value.

Value Mode

This setting is only available for sensor channels that return absolute values. It is not available for sensors showing difference values, such as traffic channels. Depending on this setting, the channel cannot only show averages, but also minimum or maximum values in the graphs for the respective time spans.

Choose between:

  • Average: The channel shows average values.
  • Minimum: The channel shows minimum values.
  • Maximum: The channel shows maximum values.

icon-book-bulbSee the Knowledge Base for more information about value modes: What is the Value Mode in channel settings?

Decimal Places

Define how many decimal places of the channel's data to display in graphs and tables. Choose between:

  • Automatic: PRTG automatically defines how many decimal places are used for optimal viewing results.
    icon-i-roundValues between 10 and –10 are rounded to two decimal places. Values that are very close to an integer are rounded to the integer, for example, 3.001 is rounded to 3.
  • All: Display all available decimal places.
  • Custom: Manually define the number of decimal places. If you choose this option, an additional field will appear. Please enter an integer value.

Spike Filter

You can use a spike filter to correct faulty monitoring data. Sometimes, sensors report enormously high or far too low values. This can be because of an error in data transmission, or because of incompatibilities of the physical device you are monitoring. This can make graphs unreadable. A spike filter can compensate for these flaws.

If you enable a spike filter, values above and below a certain limit are disregarded in the monitoring data for graphs and tables.

Choose between:

  • Disable Filtering: Display all data as it is received. Do not filter out spikes.
  • Enable Filtering: Enable a filter to remove spike values. Additional fields appear below.
    icon-i-roundThis does not change monitoring data itself but only the presentation of the data. This setting is valid for all data of this channel, including historic data.

icon-i-roundThe spike filter option is not available for the channel Downtime.

Spike Filter Max. Value [unit]

This field is only visible if you enable the spike filter above. Enter the maximum value to show in the channel data. PRTG will disregard all data above this value in graphs and tables. Please enter an integer value or leave the field empty.

Spike Filter Min. Value [unit]

This field is only visible if you enable the spike filter above. Enter the minimum value to show in the channel data. PRTG will disregard all data below this value in graphs and tables. Please enter an integer value or leave the field empty.

Vertical Axis Scaling

Define how to display the vertical axis for the channel in graphs. Choose between:

  • Automatic Scaling: PRTG automatically uses the optimum scaling. Usually the scaling ranges from the minimum to the maximum value. PRTG uses one single scale for each unit label only.
  • Manual Scaling: Define the scaling manually. Additional fields appear below. Defining manual axis scaling can make low values better visible in your graph, but it may result in a graph with multiple vertical axes for the same unit label.

icon-i-roundSettings for this option are ignored if you enable the Chart Type Stack channels on top of each other or Show in and out traffic as positive and negative area chart (available for traffic sensors) on the sensor's Settings tab.

Vertical Axis Maximum [unit]

This field is only visible if you enable vertical axis scaling above. Enter the maximum value to use on the vertical axis for the channel. Please enter an integer value.

Vertical Axis Minimum [unit]

This field is only visible if you enable vertical axis scaling above. Enter the minimum value to use on the vertical axis for the channel. Please enter an integer value.

Limits

Define if you want to use thresholds for this channel. The channel can affect the status of the sensor it is part of. With limits you can define when the sensor will show a Warning or Down status, depending on the channel data. For example, you can use this function to set a traffic sensor (which is usually never in a down state) to error when the monitored values reach critical limits.

Choose between:

  • Disable Limits: Do not use the channel data to control the sensor status.
  • Enable Limits: Define limits. Additional fields appear below. The sensor of this channel will enter a Warning or Down status when limits are undercut or overrun.

icon-i-round-redIf a channel uses lookups, we strongly recommend that you control the sensor status only via the lookup definition. If you define limits in addition here, the sensor will use both the channel limits and the status as defined in the lookup file. In this case, channel limits will determine the overall status of the sensor and overwrite the sensor message while the channel gauge still shows the status as defined in the lookups.

icon-i-roundThe limits option is not available for the Downtime channel.

icon-i-roundYou can show limits in graphs (highlighted in yellow or red) if you select exactly one channel with a limit in a graph.

Upper Error Limit [unit]

This field is only visible if you enable limits above. Specify an upper limit for a Down status. If the channel values overrun this value, the sensor will be Down. Please enter an integer value or leave the field empty.

icon-i-roundWhile a sensor shows a Down status triggered by a limit, it will still receive data in its channels.

Upper Warning Limit [unit]

This field is only visible if you enable limits above. Specify an upper limit for a Warning status. If the channel values overrun this value, the sensor will be Warning. Please enter an integer value or leave the field empty.

Lower Warning Limit [unit]

This field is only visible if you enable limits above. Specify a lower limit for a Warning status. If the channel values undercut this value, the sensor will be Warning. Please enter an integer value or leave the field empty.

Lower Error Limit [unit]

This field is only visible if you enable limits above. Specify a lower limit for a Down status. If the channel values undercut this value, the sensor will be Down. Please enter an integer value or leave the field empty.

icon-i-roundWhile a sensor shows a Down status triggered by a limit, it will still receive data in its channels.

Error Limit Message

This field is only visible if you enable limits above. Enter an additional message. It will be added to the sensor message when showing a Down status. Please enter a string or leave the field empty.

Warning Limit Message

This field is only visible if you enable limits above. Enter an additional message. It will be added to the sensor message when showing a Warning status. Please enter a string or leave the field empty.

icon-ok-greenClick Ok to save your settings and to close the settings window. Click Apply to save the changed settings while the Edit Channel window remains open. This functionality is useful if you want to change the settings of other channels of the current sensor as well. You can select another channel via the dropdown menu above the settings. You can close the settings window without saving by clicking Cancel.

icon-i-roundIf you have changed any settings and click Cancel or choose another channel via the dropdown menu without applying the changes, PRTG will ask you to confirm this step. Discard Changes will ignore any edits and closes the window or shows the settings of another selected channel. Click Save to apply your changes.

More

Knowledge Base: What is the Value Mode in channel settings?

Sensor Settings Overview

For information about sensor settings, see the following sections:

Ajax Web Interface—Device and Sensor Setup—Topics

Other Ajax Web Interface Sections

Related Topics