Sometimes you need a SCOM monitor which was calculated from one or more SNMP values. Maybe the values have to be calculated, cause the value is in an unhandy format or unit. In this example i will monitor the input frequency for an for an UPS. The originaly readed value is in 1/10 Hz, but i like to monitor in Hz.
Create the monitor
Select Timed Script Two State Monitor and select the destination managementpack. 
Insert this code to the field Script:
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Dim oAPI, oBag Set oAPI = CreateObject("MOM.ScriptAPI") On Error Resume Next err.clear Dim oArgs Set oArgs = WScript.Arguments strDeviceIP = oArgs(0) strCommunity = Decode(oArgs(1)) set objSNMP = CreateObject("OlePrn.OleSNMP") objSNMP.Open strDeviceIP, strCommunity, 2, 1000 intValue = Int(objSNMP.Get(".1.3.6.1.2.1.33.1.4.2.0")) intValue = intValue / 10 ' Return the values to SCOM Set oBag = oAPI.CreatePropertyBag() If intValue < 45 Or intValue > 55 Then Call oBag.AddValue("devState", "BAD") Else Call oBag.AddValue("devState", "GOOD") End If Call oBag.AddValue("PerfValue", intValue ) Call oAPI.Return(oBag) Function Decode(strB64) ' decode CommunityString strXML = "<B64DECODE xmlns:dt=" & Chr(34) & _ "urn:schemas-microsoft-com:datatypes" & Chr(34) & " " & _ "dt:dt=" & Chr(34) & "bin.base64" & Chr(34) & ">" & _ strB64 & "</B64DECODE>" Set oXMLDoc = CreateObject("MSXML2.DOMDocument.3.0") oXMLDoc.LoadXML(strXML) decode = oXMLDoc.selectsinglenode("B64DECODE").nodeTypedValue set oXMLDoc = nothing End Function |
As you see, you have to define the SNMP OID in the script. After this you can calculate with the returned value and define rules for the GOOD and BAD state.
To get the devices ip address and communitystring, you have to define this parameters, which could be readed by the script with Wscript.Arguments. Click to the Parameters-button:
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$Target/Property[Type="MicrosoftSystemCenterNetworkDeviceLibrary6172210!Microsoft.SystemCenter.NetworkDevice"]/IPAddress$ $Target/Property[Type="MicrosoftSystemCenterNetworkDeviceLibrary6172210!Microsoft.SystemCenter.NetworkDevice"]/CommunityString$ $Target/Property[Type="MicrosoftSystemCenterNetworkDeviceLibrary6172210!Microsoft.SystemCenter.NetworkDevice"]/Version$ |
Please note, that all parameters have to be insert as one (1) line, separated only with a space.
You created your first calculated SNMP monitor, but you didn’t enable it. To enable it, you have to create an override for a group, containing the desired devices.