When monitoring specific OIDs with a custom SNMP sensor, the sensor shows the error message that ''x' is not a valid floating point'. What does this mean and what can I do about it?

Article Comments

This article applies to PRTG Network Monitor 18 or later

Workaround for ''x' is not a valid floating point value'

You might receive the error message 'x' is not a valid floating point value when you use SNMP Custom, SNMP Custom Advanced, or SNMP Library sensors to monitor an OID that returns a value with a comma "," like 27,5545 as a float value.

Check the Value Returned by the OID

  • Download and install SNMP Tester.
  • Open the SNMP Tester and enter the following information.
    • The Device IP/Port of the device.
    • The SNMP Version as configured on the device.
    • The Community as configured on the device.
    • Select Custom OID and enter the OID you want to monitor. In this example, we use 1.3.6.1.4.1.6574.4.3.2.1.0 that corresponds to the UPS Battery Voltage value of a UPS device.
  • Click Start to execute the request.

Request Results
Click to enlarge.

The value 29,14885454 is correct and includes a comma but it is read as a string value and not a float value.

  • In SNMP Tester, set Read As to Float.
  • Click Start to execute the new request.

Incorrect Request Results
Click to enlarge.

The value 2914885454 is incorrect because it does not contain a decimal separator. The float value returned by the SNMP request must contain a dot '.' as decimal separator, otherwise PRTG cannot interpret the value.

Solution: Create an SNMP Custom String Sensor

The SNMP Custom String sensor allows you to extract a floating point value from a string result using a regular expression.

  • Add an SNMP Custom String sensor to the device.
  • Under OID Value, enter the OID. In our example it is 1.3.6.1.4.1.6574.4.3.2.1.0.
  • In section Extended Processing, select Extract a numeric value using a regular expression.
    • Under Regular Expression, enter ([0-9]+),([0-9]+) to convert the float value into an integer value.
    • Under Index of Capturing Group, enter 2.
    • Under Decimal Separator, enter a comma ','.
    • Under Thousands Separator, enter a comma ','.
  • Save your settings.

The sensor now shows the correct value. Sensor Result
Click to enlarge.

See Also


Jan, 2019 - Permalink