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Can I change the Value Type (Gauge/Delta) of an existing SNMP Custom sensor in PRTG?

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I have created a Custom SNMP sensor. Now I want to change the Value Type of this sensor afterwards, from Gauge to Delta or vice-versa.

The web interface does not offer changing this setting. What can I do?

custom-sensor prtg sensor snmp snmp-sensor value-type

Created on Feb 17, 2010 12:36:42 PM by  Daniel Zobel [Paessler Support]

Last change on Feb 17, 2010 2:04:39 PM by  Daniel Zobel [Paessler Support]



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This article applies to PRTG Network Monitor 12 or later, as well as to previous (deprecated) versions

Understanding Delta and Gauge

When defining custom sensors for PRTG one is faced with the option to define the sensor either as a Delta counter (difference per period) or one of several Gauge counters (absolute value).

Basically, when using Delta counters, the difference between the previously scanned value and the new value is computed and the resultant is handled as the monitoring value, i.e. if the first scan returns a value of "4" and the second scan a value of "6", the actual resultant value recorded for the sensor in case would be "2". This resultant is calculated for each scanning interval.

On the other hand, when using Gauge counters the value returned by the monitored device is actually used as the monitoring value. As such if the device returns a value of "2000" this value is logged as the actual sensor value.

Changing existing PRTG custom sensors from Delta to Gauge (and vice-versa)

The SNMP Custom sensor offers the following Value Types:

  • Gauge (unsigned Integer, e.g. "10", "120")
  • Gauge (signed Integer, e.g. "-12", "120")
  • Gauge (Float, e.g. "-5.80", "8.23")
  • Delta (Counter)

Once selected, the sensor type cannot be changed in the PRTG web interface. If you have selected a wrong Value Type, the easiest way to fix this is deleting an existing sensor and adding it anew, using another Value Type setting.

Created on Feb 17, 2010 1:26:26 PM by  Daniel Zobel [Paessler Support]

Last change on Jun 3, 2014 4:50:51 PM by  Gerald Schoch [Paessler Support]



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This article applies to PRTG Network Monitor 7 or later

Important: The Procedure Described in This Article is Not Recommended And Can Cause Failure to Your Configuration!

Editing the PRTG Configuration.dat file is an alternative option, but we do not recommend nor support this option. The following procedure worked in the past, but we can not guarantee that it will work for your setup.

However, this article explains how to edit the XML configuration file to change your sensors.

Editing "PRTG Configuration.dat" File

  • Stop all PRTG services in PRTG Server Administrator (otherwise the changes will not be saved).
  • In the PRTG web interface, look up the sensor ID of the sensor you want to change the value type for. To do so, select the individual sensor - the ID will be displayed next to the sensor name (in parentheses).
  • See How PRTG Network Monitor Stores its Data and look up PRTG's data paths.
  • In the PRTG data directory open the file PRTG Configuration.dat in a text editor (make a backup copy before).
  • Search for the sensor ID.
  • From under the sensor definition, change the values of the tags <snmptype> and <mode> in order to fit the right value type. For example, the code may look like this:
                        <snmptype>
                          abs
                        </snmptype>
[...]
                        <decimalmode>
                          <flags>
                            <empty/>
                          </flags>
                          <cell>
                            0
                          </cell>
                        </decimalmode>
[...]
                        <mode>
                          Absolute
                        </mode>
  • Please refer to the table below to find the right values. Note: A wrong combination of tag values can cause a 'crash' of your configuration.
Value Type<snmptype>-Value<decimalmode>-Value<mode>-Value
Gauge (unsigned Integer)abs0Absolute
Gauge (signed Integer)sign0Absolute
Gauge (Float)float1Absolute
Delta (Counter)diff0Difference
  • After saving the .DAT file, the value type of the respective sensor is changed.
  • Force to recalculate the historic data when restarting PRTG by deleting the PRTG Graph Data Cache.dat file within the data directory.
  • Restart the PRTG services in PRTG Server Administrator.

Created on Feb 17, 2010 1:59:44 PM by  Daniel Zobel [Paessler Support]

Last change on Apr 18, 2012 11:49:37 AM by  Daniel Zobel [Paessler Support]



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In our case we changed the <snmptype> value from abs to float, but the sensor values were still displayed in integer format. By comparison of configuration of two sensors ("float-changed" vs. "float-de-novo") we found, that also the value <decimalmode> must be changed from 0 to 1 to take affect. After server restart all changed values are displayed correctly as decimals.

<decimalmode>
   <flags>
      <empty/>
   </flags>
   <cell>
      1
   </cell>
</decimalmode>

Created on May 4, 2010 6:39:22 PM by  Petr Bily (0)

Last change on Jun 4, 2010 12:28:41 PM by  Daniel Zobel [Paessler Support]



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Disclaimer: The information in the Paessler Knowledge Base comes without warranty of any kind. Use at your own risk. Before applying any instructions please exercise proper system administrator housekeeping. You must make sure that a proper backup of all your data is available.