PRTG Manual: Modbus RTU Custom Sensor

The Modbus RTU Custom sensor connects to a Modbus Remote Terminal Unit (RTU) server and monitors up to ten returned numeric values.

Modbus RTU Custom Sensor

Modbus RTU Custom Sensor

i_square_cyanFor a detailed list and descriptions of the channels that this sensor can show, see section Channel List.

Sensor in Other Languages

  • Dutch: Modbus RTU Custom
  • French: Modbus RTU Custom
  • German: Modbus RTU Custom
  • Japanese: Modbus RTU Custom
  • Portuguese: Modbus RTU Custom
  • Russian: Modbus RTU Custom
  • Simplified Chinese: Modbus RTU Custom
  • Spanish: Modbus RTU Custom

Remarks

  • You can only create this sensor on a probe device, either a local probe device or a remote probe device.
  • This sensor supports the IPv6 protocol.
  • This sensor has a very low performance impact.
  • This sensor always uses the serial port of the probe device.
  • This sensor uses lookups to determine the status values of one or more channels. This means that possible states are defined in a lookup file. You can change the behavior of a channel by editing the lookup file that the channel uses. For details, see section Define Lookups.
  • See the Knowledge Base: How can I apply Zoom Service Status sensors and Modbus sensors via device templates?

i_podYou cannot add this sensor to the hosted probe of a PRTG Hosted Monitor instance. If you want to use this sensor, add it to a remote probe device.

Add Sensor

The Add Sensor dialog appears when you manually add a new sensor to a device. It only shows the settings that are required to create the sensor. You can change nearly all settings on the sensor's Settings tab after creation.

Modbus Channel Specific

Setting

Description

Channel #1 - #10 Name

Enter a name for the channel.

i_round_blueAfter sensor creation, you can change the name of the channel in the channel settings under Name.

Channel #1 - #10 Register Type

Select the type of the register. Choose between:

  • Coil: Coil numbers start with 0 and range from 00001 to 09999.
  • Discrete input: Discrete input numbers start with 1 and range from 10001 to 19999.
  • Input register: Input register numbers start with 3 and range from 30001 to 39999.
  • Holding register: Holding register numbers start with 4 and range from 40001 to 49999.
  • Input register bit: Select Input register bit to monitor a specific bit of the received value. Input register numbers start with 3 and range from 30001 to 39999.
  • Holding register bit: Select Holding register bit to monitor a specific bit of the received value. Holding register numbers start with 4 and range from 40001 to 49999.

i_round_redIt is not possible to change the register type after sensor creation.

Channel #1 - #10 Data Type

This field is only visible if you select Input register or Holding register above. Select the data type of the register. Choose between:

  • 16-bit integer
  • Unsigned 16-bit integer
  • 32-bit integer
  • Unsigned 32-bit integer
  • 64-bit integer
  • Float
  • Double

i_round_redIt is not possible to change the data type after sensor creation.

Channel #1 - #10 Unit

This field is only visible if you select Input register or Holding register under Channel #x Register Type. Enter a unit for the channel.

After sensor creation, you can change the unit of the channel in the channel settings under Unit.

Channel #2 - #10

You can create up to 10 different channels for this sensor. You must define at least one data channel, so you see all available settings for Channel #1 without manually enabling it. Additionally, you can define Channel #2 to Channel #10. To do so, choose between:

  • Disable (default): The sensor does not create this channel.
  • Enable: The sensor creates this channel. Specify at least the name, type, and register number for this channel below.

i_round_redYou cannot add additional channels after sensor creation.

Basic Sensor Settings

Click the Settings tab of a sensor to change its settings.

Basic Sensor Settings

Basic Sensor Settings

Setting

Description

Sensor Name

Enter a name to identify the sensor.

Parent Tags

Shows tags that the sensor inherits from its parent device, parent group, and parent probe.

i_round_blueThis setting is for your information only. You cannot change it.

Tags

Enter one or more tags. Confirm each tag with the Spacebar key, a comma, or the Enter key. You can use tags to group objects and use tag-filtered views later on. Tags are not case-sensitive. Tags are automatically inherited.

i_round_blueIt is not possible to enter tags with a leading plus (+) or minus (-) sign, nor tags with parentheses (()) or angle brackets (<>).

i_round_blueFor performance reasons, it can take some minutes until you can filter for new tags that you added.

The sensor has the following default tags that are automatically predefined in the sensor's settings when you add the sensor:

  • modbus

Priority

Select a priority for the sensor. This setting determines the position of the sensor in lists. The highest priority is at the top of a list. Choose from the lowest priority (i_priority_1) to the highest priority (i_priority_5).

Modbus RTU Specific

Modbus RTU Specific

Modbus RTU Specific

Setting

Description

Device COM Port

Enter the component object model (COM) port of the serial port device.

i_round_blueOn Windows systems, the COM port of the device looks like this, for example: COM3.

Baud Rate

Enter the speed of the serial connection in baud. The default baud rate is 9600.

Parity

Select the parity of the serial connection. Choose between:

  • None (default)
  • Even
  • Odd

Data Bits

Select the number of the data bits of the serial connection. Choose between:

  • 8 (default)
  • 7
  • 6
  • 5

Stop Bits

Select the number of stop bits of the serial connection. Choose between:

  • 1 (default)
  • 2

Retry Attempts

Enter the number of retries until a timeout occurs. If you enter 0, the sensor does not retry the communication attempt. The default value is 3. Enter an integer.

Receive Timeout (msec)

Enter a receive timeout in milliseconds (msec). If the reply from the device takes longer than this value, the request is aborted and triggers an error message. The default value is 500 msec (0.5 seconds).

Unit ID

Enter the Modbus unit ID that you want to monitor.

i_round_blueIn a standard Modbus network, there are up to 247 unit IDs, each with a unique assigned identifier from 1 to 247.

Byte Order

Select the sequence of the transmitted information. Choose between:

  • Big-endian (AB CD)
  • Little-endian (DC BA)
  • Big-endian byte swap (BA DC)
  • Little-endian byte swap (CD AB)

Modbus Channel Specific

Modbus Channel Specific

Modbus Channel Specific

Setting

Description

Channel #1 - #10 Register Type

Shows the register type of the channel value.

i_round_bluePRTG shows this value for reference purposes only. If you need to change this value, add the sensor anew.

Channel #1 - #10 Register Number

Enter the register number from which you want to retrieve information.

i_round_redThe register number must be a number that contains one to five digits. The sensor supports numbers between 0 and 65534.

i_round_blueDepending on your Modbus device, you may need to remove the register type prefix. For example, you need to enter 60 for the input register 30060 or 316 for the holding register 40316.

Channel #1 - #10 Value Type

This field is only visible if you select Input register or Holding register under Channel #x Register Type. Select the value type that the channel displays. Choose between:

  • Absolute: Integer64 values with or without an operational sign, such as 10 or 120 or -12 or 120.
  • Delta (counter): The sensor calculates the difference between the last value and the current value. The sensor additionally divides the delta value by a time period to indicate a speed value. The sensor ignores this setting if you select Double or Float as Channel #x Data Type.
    i_round_redThis mode only works if the difference between the last and the current value is positive and increases with each scanning interval. This mode does not support negative values and decreasing values.

Channel #1 - #10 Data Type

This field is only visible if you select Input register or Holding register under Channel #x Register Type. Shows the Data Type of the Register Number.

i_round_bluePRTG shows this value for reference purposes only. If you need to change this value, add the sensor anew.

Channel #1 - #10 Register Width

This field is only visible if you select Input register bit or Holding register bit under Channel #x Register Type. Select the width of the value in the register. Choose between:

  • 16 bits wide (default)
  • 32 bits wide
  • 64 bits wide

Channel #1 - #10 Bit Index

This field is only visible if you select Input register or Holding register under Channel #x Register Type. Enter the index of the bit that you want to monitor.

i_round_blueEnter a value between 0 and 15, 31, or 63, depending on the Channel #1 - #10 Register Width. 0 monitors the least significant bit. To monitor the most significant bit, enter 15 for a 16-bit register, 31 for a 32-bit register, or 63 for a 64-bit register.

Sensor Display

Sensor Display

Sensor Display

Setting

Description

Primary Channel

Select a channel from the list to define it as the primary channel. In the device tree, the last value of the primary channel is always displayed below the sensor's name. The available options depend on what channels are available for this sensor.

i_round_blueYou can set a different primary channel later by clicking b_channel_primary below a channel gauge on the sensor's Overview tab.

Graph Type

Define how different channels are shown for this sensor:

  • Show channels independently (default): Show a graph for each channel.
  • Stack channels on top of each other: Stack channels on top of each other to create a multi-channel graph. This generates a graph that visualizes the different components of your total traffic.
    i_round_redYou cannot use this option in combination with manual Vertical Axis Scaling (available in the channel settings).

Stack Unit

This setting is only visible if you enable Stack channels on top of each other as Graph Type. Select a unit from the list. All channels with this unit are stacked 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.

Debug Options

Debug Options

Debug Options

Setting

Description

Result Handling

Define what PRTG does with the sensor result:

  • Discard result: Do not store the sensor result.
  • Store result: Store the last sensor result in the \Logs\sensors subfolder of the PRTG data directory on the probe system. The file name is Result of Sensor [ID].log. This setting is for debugging purposes. PRTG overwrites this file with each scanning interval.

i_podThis option is not available when the sensor runs on the hosted probe of a PRTG Hosted Monitor instance.

i_round_blueIn a cluster, PRTG stores the result in the PRTG data directory of the master node.

Inherited Settings

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 b_inherited_enabled under the corresponding setting name to disable the inheritance and to display its options.

i_square_cyanFor more information, see section Inheritance of Settings.

Scanning Interval

Scanning Interval

Scanning Interval

i_square_cyanFor more information, see section Root Group Settings, section Scanning Interval.

Schedules, Dependencies, and Maintenance Window

i_round_blueYou cannot interrupt the inheritance for schedules, dependencies, and maintenance windows. The corresponding settings from the parent objects are always active. However, you can define additional schedules, dependencies, and maintenance windows. They are active at the same time as the parent objects' settings.

Schedules, Dependencies, and Maintenance Window

Schedules, Dependencies, and Maintenance Window

i_square_cyanFor more information, see section Root Group Settings, section Schedules, Dependencies, and Maintenance Window.

Access Rights

Access Rights

Access Rights

i_square_cyanFor more information, see section Root Group Settings, section Access Rights.

Channel Unit Configuration

i_round_blueWhich channel units are available depends on the sensor type and the available parameters. If no configurable channels are available, this field shows No configurable channels.

Channel Unit Configuration

Channel Unit Configuration

i_square_cyanFor more information, see section Root Group Settings, section Channel Unit Configuration.

Channel List

i_round_blueWhich 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 in percent.

[Value]

The returned numeric values in up to ten channels

More

i_square_blueKnowledge Base

How can I apply Zoom Service Status sensors and Modbus sensors via device templates?

What security features does PRTG include?

For more information about sensor settings, see the following sections: