There is no way to trigger backup of a protection group manually in DPM Management Console.

Use the following script from within DPM Management Shell to trigger tape backup of a protection group.

You will need to provide DPM server name, protection group name and backup option (‘LongTerm’ for tape backup).

param([string] $dpmname, [string] $pgname, [string] $backupoption)
if(!$dpmname)
{
    $dpmname = read-host "DPMName"
}
if(!$pgname)
{
    $pgname =  read-host "pgName"
}
if(!$backupoption)
{
    $backupoption =  read-host "BackOption"
}
write-Output "Creating $backupoption Recovery Point"
trap{"Error in execution... $_";break}
&{
    write-Output "Getting protection group $pgname in $dpmname..."
    $clipg = Get-ProtectionGroup $dpmname | where { $_.FriendlyName -eq $pgname}
    if($clipg -eq $abc)
    {
        Throw "No PG found"
    }
    write-Output "Getting DS from PG $pgname..."
    $backupds = @(Get-Datasource $clipg)
    foreach ($ds in $backupds)
    {
        write-Output "Creating Recovery point for $ds..."
        $j = New-RecoveryPoint -Datasource $ds -Tape -ProtectionType $backupoption
        $jobtype = $j.jobtype
        Write-Output "$jobtype Job has been triggerred..."
    }
}