CIM_DATETIME Conversion Functions

Also known as WMI Time, or WBEM DateTime,  CIM_DATETime, https://msdn.microsoft.com/en-us/library/aa387237(v=vs.85).aspx, is that odd Windows DateTime format that shows values looking like “20160905103517.816236-240”  The COM Object that presents this is  WbemScripting.SWbemDateTime, and you frequently see code to convert to this format using it, or a tortuous series of string manipulations.  My rule of thumb is this:  If you can avoid using a COM object, you should.  Here are two  functions to handle these dates using .NET.

Function ConvertTo-CIMDateTime{
     [OutputType([string])]
        Param
        (
            # oDT a dateTime object
            [Parameter(Mandatory=$true,  Position=0)]
            $oDT,
            # NoUTC is switch to remove UTC data, replacing with 000
            [Parameter(Mandatory=$False,  Position=1)]
            [switch]$NoUTC
)
   $CIMDT = [management.managementdatetimeconverter]::ToDmtfDateTime($oDT)
   if ($NoUTC){$CIMDT.SubString(0,22)+'000' }ELSE { $CIMDT }
}

The second function converts from the CIM DateTime string back to an ordinary date object:

Function ConvertFrom-CIMDateTime{
 [OutputType([datetime])]
    Param
    (
        # strDMTF is string in CIM_DateTime format
        [Parameter( Mandatory=$true, Position=0)]
        $strDMTF
        )
   [management.managementdatetimeconverter]::todatetime($strDMTF)
}

An example of the output:

#Example
$now = Get-date
$now

$CIMDate= ConvertTo-CIMDateTime $now 
$CIMDate
ConvertFrom-CIMDateTime $CIMDate

Monday, September 5, 2016 10:35:17 AM
20160905103517.816236-240
Monday, September 5, 2016 10:35:17 AM