Powershell script to check TPM Manufacturer Version with (IF ELSE) - powershell

Question

I'm trying to downgrade TPM on several HP laptops. I'm attempting to create a powershell script that will grab the TPM Manufacturer Version number, and check that number against a list of possible numbers. Once it matches one of those number execute the program to downgrade the TPM version.
I started with throwing the output into a variable, and attempting to check the variable against a static number to start the correct program. The variable is stored, but when I try to check it against "7.61" it doesn't seem to be actually checking the result. The result of 7.61 is not returning "Success"
I realize powershell is different, and my IF ELSE statements are probably just outdated. Any help would be very appreciated!
Assume TPM ManufacturerVersion is 7.61
$variable = get-WmiObject -Namespace root\cimv2\security\microsofttpm -Class Win32_Tpm | Select-Object ManufacturerVersion | Out-String
if($variable -eq "8"){
Write-Host "success"
}else{
Write-Host "Fail"
}
enter image description here

Answer 1

You are comparing strings, rather than 'versions'. If you are only checking for simple equality, then using a direct string comparison will do:
PS C:\> "10.5" -eq "10.5"
True
However, if you want to determine, say, if one version is greater than another, strings won't work. For example:
PS C:\> "100.5" -gt "55.3"
False
In that case, you should cast the version strings to actual Version types, then the comparison will work properly. For example:
$tmp = Get-WmiObject -Namespace "root\cimv2\security\microsofttpm" -Class Win32_TPM
if ([Version]$tmp.ManufacturerVersion -eq [Version]"8.0")
{
"Success"
}
else
{
"Fail"
}
Also, if you need to compare the TPM version against multiple possibilities, then a switch statement makes for neater code:
$tmp = Get-WmiObject -Namespace root\cimv2\security\microsofttpm -Class Win32_TPM
Set-Location "C:\Users\ADministrator\Desktop\TPM Downgrade"
switch([Version]$tmp.ManufacturerVersion)
{
{$_ -eq [Version]"7.62"} { '.\7.62 downgrade.cmd'}
{$_ -eq [Version]"7.61"} { '.\7.61 downgrade.cmd'}
{$_ -eq [Version]"7.60"} { '.\7.60 downgrade.cmd'}
{$_ -eq [Version]"7.41"} { '.\7.41 downgrade.cmd'}
{$_ -eq [Version]"7.40"} { '.\7.40 downgrade.cmd'}
default {"Unable to find downgrade BIN for your firmware version"}
}

Answer 2

Try this one
$variable = get-WmiObject -Namespace root\cimv2\security\microsofttpm -Class Win32_Tpm | Select-Object ManufacturerVersion
if($variable.ManufacturerVersion -eq "8"){
Write-Host "success"
}else{
Write-Host "Fail"
}

Answer 3

Thank you all for your feedback and help. This is the final product and its working great.
$tmp = get-WmiObject -Namespace root\cimv2\security\microsofttpm -Class Win32_TPM
Set-Location "C:\Users\ADministrator\Desktop\TPM Downgrade"
if ([Version]$tmp.ManufacturerVersion -eq [Version]"7.62"){
& '.\7.62 downgrade.cmd'
}elseif ([Version]$tmp.ManufacturerVersion -eq [Version]"7.61"){
& '.\7.61 downgrade.cmd'
}elseif ([Version]$tmp.ManufacturerVersion -eq [Version]"7.60"){
& '.\7.60 downgrade.cmd'
}elseif ([Version]$tmp.ManufacturerVersion -eq [Version]"7.41"){
& '.\7.41 downgrade.cmd'
}elseif ([Version]$tmp.ManufacturerVersion -eq [Version]"7.40"){
& '.\7.40 downgrade.cmd'
}else{
Write-Host "Unable to find downgrade BIN for your firmware version"
}