Public Class Form1
...

    Private Sub COM1_DataReceived(ByVal sender As Object, ByVal e As System.IO.Ports.SerialDataReceivedEventArgs) Handles COM1.DataReceived

        Dim codice As String = Replace(COM1.ReadExisting, vbCrLf, "")
        HandleData(codice)
        
    End Sub

    Private Sub HandleData(ByVal SerData As String)
        Dim conn As New SqlConnection, cm As New SqlCommand
        Dim dr As SqlDataReader

        ncard = SerData
        Try
            conn.ConnectionString = "Server=.\DEVEL; Database=DB; Integrated Security=SSPI"
            conn.Open()
            cm.CommandText = "SELECT Nome, Cognome FROM Anagrafiche WHERE nCard LIKE '%" & SerData & "'"
            cm.Connection = conn
            dr = cm.ExecuteReader()

            If dr.HasRows Then
                dr.Read()
                
                'nome e cognome sono dichiarate globali e usate nell'evento Form2_Load
                nome = dr.Item("nome")
                cognome = dr.Item("Cognome")
                
            Else
                MsgBox("CARD NON REGISTRATA")
            End If

            Form2.Show()

        Catch ex as Exception
            MsgBox("ERRORE GENERALE: " & ex.Message)
        Finally
            conn.Close()
            conn.Dispose()           
            dr.Dispose()
            cm.Dispose()
        End Try


    End Sub

...
End Class