The Simple Network Management Protocol (SNMP) is a network protocol developed by the IETF to monitor and control network elements. Possible tasks that can be realised via SNMP include the remote monitoring of UPSs via a network connection.
Most business and enterprise UPSs have a network management card included or have a slot where such a card can be added. This management card enables remote monitoring of the UPS.
OPMONis makes use of the SNMPv1 protocol to query the following parameters from your UPS:
- The time the UPS is running on battery: This indicates wether the UPS is running on power or on battery
- The remaining runtime and remaining charge of the battery: Depending on these values OPMONis will trigger the shutdown or startup of your systems
- The battery replacement indiciator: Used to monitor the status of your UPS.
- The battery fault indiciator: Used to monitor the status of your UPS.
The SNMPv1 protocol uses object identifiers (OID) to identify the variable requested. Unfortunately it is not always easy the identify the correct OID numbers which are required by OPMONis to query the status of the UPS.
RFC 1628 defines a Management Informatino Base (MIB), which defines the most important OID values for a UPS. However, it is up to the manufacturer of the UPS whether this standard MIB is used.
OID for Running on Battery
To detect if the power has failed and the UPS is running on battery, the “Running on Battery” value is used. The value is checked by using the specified regual expression. By default, a value not equal “0” is considered as running on battery.
| Default | 1.3.6.1.2.1.33.1.2.2 |
| MIB Object Name | upsSecondsOnBattery |
| Description | If the unit is on battery power, the elapsed time since the UPS last switched to battery power. Zero shall be returned if the unit is not on battery power. |
| Regex |
^[1-9][0-9]*$ Specifies the regular expression which have to produce a match in order to detect that the UPS is running on battery. |
OID for Minutes Remaining
If the power has failed and the UPS is running on battery, the remaining runtime (and the remaining charge) of the UPS is used to set the time at which OPMONis starts the shutdown of the systems.
| Default | 1.3.6.1.2.1.33.1.2.3 |
| MIB Object Name | upsEstimatedMinutesRemaining |
| Description | An estimate of the time to battery charge depletion under the present load conditions if the utility power is off and remains off, or if it were to be lost and remain off. |
| Multiplier | Most UPS return the remaining time in minutes. However, some UPS use other units for this value. To accommodate the different units, the multiplier gives a value that is multiplied by the value returned by the UPS. The result must be the remaining runtime in minutes. |
OID for Charge Remaining
If the power has failed and the UPS is running on battery, the remaining charge (and the remaining runtime) of the UPS is used to set the time at which OPMONis starts the shutdown of the systems.
| Default | 1.3.6.1.2.1.33.1.2.4 |
| MIB Object Name | upsEstimatedChargeRemaining |
| Description | An estimate of the battery charge remaining expressed as a percent of full charge. |
| Multiplier | Most UPS return the remaining charge in percent. However, some UPS use seconds or other units for this value. To accommodate the different units, the multiplier gives a value that is multiplied by the value returned by the UPS. The result must be the remaining charge in percent. |
OID for Battery Replacement
This optional setting allows OPMONis to monitor the battery status and warn you when the UPS signals that the battery needs replacing. If this OID is not set, monitoring of the battery replacement is disabled.
| Default | |
| MIB Object Name | batteryReplace or batteryReplacmentIndicator |
| Description | Indicates whether the UPS batteries need replacing. |
| Regex |
^[1]$ Specifies the regular expression which have to produce a match in order to detect that the UPS needs replacement. |
OID for Battery Fault
With this optional setting, OPMONis can monitor the battery status and warn you when the UPS reports a battery failure. If this OID is not set, battery failure monitoring is disabled.
| Default | |
| MIB Object Name | batteryFault or batteryFaultIndicator |
| Description | Indicates a battery failure. |
| Regex |
^[1]$ Specifies the regular expression which have to produce a match in order to detect that the UPS needs replacement. |
