Find serial port where my device is connected - vb.net

Question

I'm starting to work with a pinpad.
I need that my program find the port where the pinpad is connected without user interaction.
I tried with:
Dim searcher As New ManagementObjectSearcher("root\cimv2","SELECT * FROM Win32_SerialPort")
For Each queryObj As ManagementObject In searcher.Get()
MsgBox(queryObj("Name"))
Next
but this only give me "COM1" and "COM2" as an answer (My device is connected to COM4)
and with
Dim searcher As New ManagementObjectSearcher("root\cimv2", "SELECT * FROM Win32_PnPEntity WHERE ConfigManagerErrorCode = 0")
For Each queryObj As ManagementObject In searcher.Get()
MsgBox(queryObj("Name"))
Next
With this one I can see my device friendly name but I don´t know how to get the port (I receive the names like 'HP printer')
Any idea of how can I get the port that I need?
Thanks in advance

Answer 1

Based on the comments it sounds like your device is a USB device that has a driver that causes it to appear to be (emulates) a serial port attached device. In that case I would use:
My.Computer.Ports.SerialPortNames
to enumerate and loop over all serial ports. Then, one at a time try to open each one and send a command to the device that you know it responds to. Most devices have some kind of heartbeat or keep alive message that they will respond to. Whichever port you get a response on is the port you need to use.

Answer 2

I want to point 2 matters:
1: here is a solution i used for this problem (efficiancy corrections will be appreciated)
I used this soution i used to figure out on which port vx805 verifone pin pad was connected (has a unique device id):
Friend Class pinPadComLocater
Private Shared com As String
Private Const PNPDeviceID = "VID_11CA&PID_0220"
Private Const scope = "root\cimv2"
Public ReadOnly pinPadCom As String = Nothing
Sub New()
If isVX805PinPadConnected() Then
pinPadCom = com
Output.mainLog(Output.pinpadLocationMsg + com)
Else
Output.mainLog(Output.pinpadNotFoundMsg)
End If
End Sub
Private Shared Function queryCom(port As String) As Boolean
Dim query = "SELECT * FROM Win32_PnPEntity WHERE ClassGuid=""{4d36e978-e325-11ce-bfc1-08002be10318}"" AND DeviceID LIKE ""%" + PNPDeviceID + "%"" AND Caption LIKE ""%" + port + "%"""
Dim resp = New ManagementObjectSearcher(scope, query).Get
If resp.Count = 1 Then Return True
For Each queryObj As ManagementObject In resp
For Each prop In queryObj.Properties 'print all data for development purposes
Try
Console.writeline(prop.Name + " : " + queryObj(prop.Name).ToString)
catch ex As Exception
End Try
Next
Next
Return False
End Function
Private Shared Function isVX805PinPadConnected() As Boolean
For Each port In My.Computer.Ports.SerialPortNames
Try
If queryCom(port) Then
com = port
Return True
End If
Catch err As ManagementException
Throw New ConstraintException("An error occurred while querying for WMI data: " & err.Message)
End Try
Next
Throw New ConstraintException("Pin Pad Com Port could not be located")
Return False
End Function
End Class
2: would love more clarifiaction on that:
Then, one at a time try to open each one and send a command to the device that you know it responds to. Most devices have some kind of heartbeat or keep alive message that they will respond to
I would love to see a code example of how you send such a heartbeat check to a pinpad