How to get the serial number of the monitors using Powershell?

Question

After a lot of research, try and error, I got a code that could get as close as possible to the monitors serial number but not the actual serial number.

$Monitors = Get-WmiObject WmiMonitorID -Namespace root\wmi
$LogFile = "C:\test\monitors.txt"

function Decode {
    If ($args[0] -is [System.Array]) {
        [System.Text.Encoding]::ASCII.GetString($args[0])
    }
    Else {
        "Not Found"
    }
}

echo "Manufacturer", "Name, Serial"

ForEach ($Monitor in $Monitors) {  
    $Manufacturer = Decode $Monitor.ManufacturerName -notmatch 0
    $Name = Decode $Monitor.UserFriendlyName -notmatch 0
    $Serial = Decode $Monitor.SerialNumberID -notmatch 0

    echo "$Manufacturer, $Name, $Serial" >> $LogFile
}

The name of manufactural is Acer but the code's output is ACR. Regarding the serial number, which I'm more interested, only a few digits matches. Is there another keywords or line of code that I can use to extract the exact (pretty long) serial number?

Answer 1

Hi,

The serial number is stored in SerialNumberID. I don't think there are other properties to pull that long serial number.
https://learn.microsoft.com/en-us/windows/win32/wmicoreprov/wmimonitorid#members

ACR is the manufacturer ID of Acer.
https://edid.tv/manufacturer/

Best Regards，
Ian Xue

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Answer 2

I think the problem is the lack of understanding about what the Get-CimInstance WmiMonitorID -Namespace root\wmi)[1].SerialNumberID -notmatch 0 is actually doing.

The "SerialNumberID" property is not a string. It's an object of type byte[] (an array of bytes). The "-notmatch" operator is acting on the individual elements of the byte array, not on the entire value. It will remove items within the byte array representation of the string that match the value of zero, not just the trailing items that match.

The whole set of code in the original poster's question can be replaced by this:

$LogFile = "c:\Junk\monitors.txt"  
Get-WmiObject WmiMonitorID -Namespace root\wmi |  
    ForEach-Object {  
        $Manufacturer   = [System.Text.Encoding]::ASCII.GetString($_.ManufacturerName).Trim(0x00)  
        $Name           = [System.Text.Encoding]::ASCII.GetString($_.UserFriendlyName).Trim(0x00)  
        $Serial         = [System.Text.Encoding]::ASCII.GetString($_.SerialNumberID).Trim(0x00)  
        "{0}, {1}, {2}" -f $Manufacturer,$Name,$Serial | Out-File $LogFile  
    }  

Adding a "Decode" function in place of a copy/paste of the string [System.Text.Encoding]::ASCII.GetString($_. just adds to the complexity and efficiency, and reduces clarity.

Answer 3

This is my version it gives the full serial number not shortened version and also asks for the hostname

$computername = Read-Host -Prompt 'Enter Hostname'
$MonitorsCMD = ""
If (!$computername)
{
$MonitorsCMD = Get-WmiObject WmiMonitorID -Namespace root\wmi
}
Else
{
$MonitorsCMD = Get-WmiObject WmiMonitorID -Namespace root\wmi -ComputerName $computername
}

$Monitors = $MonitorsCMD
$LogFile = "C:\monitors.txt"

#"Manufacturer,Name,Serial" | Out-File $LogFile
echo "Name, Serial"

For($i=0; $i -le ($Monitors.Count - 1); $i++)
{
    $nm = $Monitors[$i].UserFriendlyName -notmatch '^0$'
    $Name = ""
    If ($nm -is [System.Array]) {
    For($j=0; $j -le ($nm.Count - 1); $j++)
    {
        $Name = $Name + [char]$nm[$j]
    }
    }
    $sr = $Monitors[$i].SerialNumberID -notmatch '^0$'
    If ($sr -is [System.Array]) {
    $Serial = ""
        For($j=0; $j -le ($sr.Count - 1); $j++)
    {
        $Serial = $Serial + [char]$sr[$j]
    }
    }
	
	#"$Name,$Serial" | Out-File $LogFile -append
     echo "$Name, $Serial"
}
PAUSE

Answer 4

The code is very nice, but you forgot some brackets:

$Serial = Decode $Monitor.SerialNumberID -notmatch 0

Should be

$Serial = Decode ($Monitor.SerialNumberID -notmatch 0)

And that does get rid of the trailing NULL values

Answer 5

In case someone is using powershell 7, Get-WmiObject has been deprecated so use Get-CimInstance instead

An example one-liner for getting your external monitor serial number

[System.Text.Encoding]::ASCII.GetString($(Get-CimInstance WmiMonitorID -Namespace root\wmi)[1].SerialNumberID -notmatch 0)