Reading Mettler Toledo PS60 Scale Data
Not so long ago, I won a project at Elance - to make a simple WinForms application in Visual Basic, which will display data from Mettler Toledo PS60 scales.
Fortunately, these scales are a USB HID device.
In this post I will describe how to work with similar HID devices in Visual Basic (and indeed in .Net)
I searched Google a little, found some interesting links.
It is generally recommended to use the Mike O'Brien's USB HID library .
Here is an article that reads data from similar weights using this library:
nicholas.piasecki.name/blog/2008/11/reading-a-stamps-com-usb-scale-from-c-sharp
What I did not like is guessing the data format. In addition, by sharing a link with the customer, he received the answer that he did not need the whole library and in general he would prefer that I solve the problem myself.
Well, we are armed with MSDN as well as the specification for the scales:
"64067860 PS scales Operation and Technical Manual.pdf" - easily searched by Google.
')
Reading data from a HID device, if you do not need any special difficulties (I will try to write about reading ACS NFC SmartCard Reader later), is quite simple:
1) you need to get the DevicePath of the device you need, like this:
(\? \ usb # vid_04a9 & pid_1097 # 207946 # {28d78fad-5a12-11d1-ae5b-0000f803a8c2})
2) open this DevicePath using the most common CreateFile function with GENERIC_READ access
3) Read with ReadFile
How to get DevicePath. The task is simple. You need to get a list of all devices, find the scales, and read the HIDD_ATTRIBUTES structure using the HidD_GetAttributes function (hidHandle, deviceAttributes)
Steps:
1) Get the device class guid
2) Create an Enumerator for a device class.
3) Go through the list of devices
4) In the nested loop we go through the list of device interfaces
5) Get the DevicePath
Here is a small trick with passing null in order to get the correct buffer size for the data. Half the task is done - we have a DevicePath.
6) Now you need to understand whether this device.
We open the device with ACCESS_NONE (we only need pid & vid, for this there is no need to open the device for reading, most devices will not allow us and here there will be an exception)
7) And read the attributes
8) Now just compare deviceAttributes.VendorID and deviceAttributes.ProductID with constants and if this is what you need - you can exit the cycles
Now actually to the weights. When reading data, they give us 6 bytes, which need to be dealt with.
According to the specification, the first byte of the parcel is the report id.
The second is the measurement status. It happens: an error, stable weight, less than zero, fluctuations, etc. The complete list is in the code and in the specification.
The third is the unit of measurement. This is understandable - milligrams, grams, kilograms, etc. Though troy ounce.
The next three bytes are the actual weight.
The first byte of weight is the power of tens, the next two are the actual value.
Thus, to get the weight value, you need to do a simple operation:
(b [5] * 256 + b [4]) * 10 ^ b [3]
That's it - it's pretty simple.
Source:
Fortunately, these scales are a USB HID device.
In this post I will describe how to work with similar HID devices in Visual Basic (and indeed in .Net)
I searched Google a little, found some interesting links.
It is generally recommended to use the Mike O'Brien's USB HID library .
Here is an article that reads data from similar weights using this library:
nicholas.piasecki.name/blog/2008/11/reading-a-stamps-com-usb-scale-from-c-sharp
What I did not like is guessing the data format. In addition, by sharing a link with the customer, he received the answer that he did not need the whole library and in general he would prefer that I solve the problem myself.
Well, we are armed with MSDN as well as the specification for the scales:
"64067860 PS scales Operation and Technical Manual.pdf" - easily searched by Google.
')
Reading data from a HID device, if you do not need any special difficulties (I will try to write about reading ACS NFC SmartCard Reader later), is quite simple:
1) you need to get the DevicePath of the device you need, like this:
(\? \ usb # vid_04a9 & pid_1097 # 207946 # {28d78fad-5a12-11d1-ae5b-0000f803a8c2})
2) open this DevicePath using the most common CreateFile function with GENERIC_READ access
NativeMethods.CreateFile(DeviceInterfaceDetailData.DevicePath, NativeMethods.GENERIC_READ, NativeMethods.FILE_SHARE_READ + NativeMethods.FILE_SHARE_WRITE, security, NativeMethods.OPEN_EXISTING, 0, 0) 3) Read with ReadFile
res = NativeMethods.ReadFile(ioHandle, bufPtr, 10, bytesRead, IntPtr.Zero) How to get DevicePath. The task is simple. You need to get a list of all devices, find the scales, and read the HIDD_ATTRIBUTES structure using the HidD_GetAttributes function (hidHandle, deviceAttributes)
Steps:
1) Get the device class guid
NativeMethods.HidD_GetHidGuid(hidClass) 2) Create an Enumerator for a device class.
DeviceInfoSet = NativeMethods.SetupDiGetClassDevs(hidClass, IntPtr.Zero, 0, NativeMethods.DIGCF_PRESENT + NativeMethods.DIGCF_DEVICEINTERFACE) 3) Go through the list of devices
Do While NativeMethods.SetupDiEnumDeviceInfo(DeviceInfoSet, deviceIndex, DeviceInfoData) 4) In the nested loop we go through the list of device interfaces
Do While NativeMethods.SetupDiEnumDeviceInterfaces(DeviceInfoSet, DeviceInfoData, hidClass, deviceIfaceIndex, DeviceInterfaceData) 5) Get the DevicePath
success = NativeMethods.SetupDiGetDeviceInterfaceDetailBuffer(DeviceInfoSet, DeviceInterfaceData, IntPtr.Zero, 0, RequiredSize, IntPtr.Zero) ' Obtain buffer size success = NativeMethods.SetupDiGetDeviceInterfaceDetail(DeviceInfoSet, DeviceInterfaceData, DeviceInterfaceDetailData, RequiredSize, RequiredSize, DeviceInfoData) ' Get device information using previously recieved buffer size Here is a small trick with passing null in order to get the correct buffer size for the data. Half the task is done - we have a DevicePath.
6) Now you need to understand whether this device.
NativeMethods.CreateFile(DeviceInterfaceDetailData.DevicePath, NativeMethods.ACCESS_NONE, NativeMethods.FILE_SHARE_READ + NativeMethods.FILE_SHARE_WRITE, security, NativeMethods.OPEN_EXISTING, 0, 0) We open the device with ACCESS_NONE (we only need pid & vid, for this there is no need to open the device for reading, most devices will not allow us and here there will be an exception)
7) And read the attributes
Dim deviceAttributes As NativeMethods.HIDD_ATTRIBUTES deviceAttributes.cbSize = Marshal.SizeOf(deviceAttributes) NativeMethods.HidD_GetAttributes(hidHandle, deviceAttributes) 8) Now just compare deviceAttributes.VendorID and deviceAttributes.ProductID with constants and if this is what you need - you can exit the cycles
Now actually to the weights. When reading data, they give us 6 bytes, which need to be dealt with.
According to the specification, the first byte of the parcel is the report id.
The second is the measurement status. It happens: an error, stable weight, less than zero, fluctuations, etc. The complete list is in the code and in the specification.
The third is the unit of measurement. This is understandable - milligrams, grams, kilograms, etc. Though troy ounce.
The next three bytes are the actual weight.
The first byte of weight is the power of tens, the next two are the actual value.
Thus, to get the weight value, you need to do a simple operation:
(b [5] * 256 + b [4]) * 10 ^ b [3]
That's it - it's pretty simple.
Source:
NativeMethods.vb
Public Class NativeMethods Public Const DIGCF_PRESENT = &H2 Public Const DIGCF_DEVICEINTERFACE = &H10 Public Const FILE_FLAG_OVERLAPPED = &H40000000 Public Const FILE_SHARE_READ = 1 Public Const FILE_SHARE_WRITE = 2 Public Const GENERIC_READ = &H80000000 Public Const GENERIC_WRITE = &H40000000 Public Const ACCESS_NONE = 0 Public Const INVALID_HANDLE_VALUE = -1 Public Const OPEN_EXISTING = 3 <StructLayout(LayoutKind.Sequential, CharSet:=CharSet.Auto)> _ Public Structure SP_DEVICE_INTERFACE_DETAIL_DATA Public cbSize As UInt32 <MarshalAs(UnmanagedType.ByValTStr, SizeConst:=256)> _ Public DevicePath As String End Structure Public Structure SP_DEVICE_INTERFACE_DATA Public cbSize As Integer Public InterfaceClassGuid As System.Guid Public Flags As Integer Public Reserved As UIntPtr End Structure Public Structure SP_DEVINFO_DATA Public cbSize As Integer Public ClassGuid As System.Guid Public DevInst As Integer Public Reserved As UIntPtr End Structure Public Const HIDP_INPUT = 0 Public Const HIDP_OUTPUT = 1 Public Const HIDP_FEATURE = 2 Public Structure HIDD_ATTRIBUTES Public cbSize As Integer Public VendorID As UShort Public ProductID As UShort Public VersionNumber As Short End Structure Public Structure SECURITY_ATTRIBUTES Public nLength As Integer Public lpSecurityDescriptor As IntPtr Public bInheritHandle As Boolean End Structure Public Declare Auto Function CreateFile Lib "kernel32.dll" (lpFileName As String, dwDesiredAccess As Integer, dwShareMode As Integer, ByRef lpSecurityAttributes As SECURITY_ATTRIBUTES, dwCreationDisposition As Integer, dwFlagsAndAttributes As Integer, hTemplateFile As Integer) As IntPtr Public Declare Auto Function ReadFile Lib "kernel32.dll" (ByVal hFile As IntPtr, ByVal Buffer As IntPtr, ByVal nNumberOfBytesToRead As Integer, ByRef lpNumberOfBytesRead As Integer, ByVal Overlapped As IntPtr) As Integer Public Declare Auto Function CloseHandle Lib "kernel32.dll" (hObject As IntPtr) As Boolean Public Declare Auto Function SetupDiGetClassDevs Lib "setupapi.dll" (ByRef ClassGuid As System.Guid, ByVal Enumerator As Integer, ByVal hwndParent As IntPtr, ByVal Flags As Integer) As IntPtr Public Declare Auto Function SetupDiDestroyDeviceInfoList Lib "setupapi.dll" (deviceInfoSet As IntPtr) As Boolean Public Declare Auto Function SetupDiEnumDeviceInfo Lib "setupapi.dll" (ByVal DeviceInfoSet As Integer, ByVal MemberIndex As Integer, ByRef DeviceInfoData As SP_DEVINFO_DATA) As Boolean Public Declare Auto Function SetupDiEnumDeviceInterfaces Lib "setupapi.dll" (ByVal DeviceInfoSet As IntPtr, ByRef DeviceInfoData As SP_DEVINFO_DATA, ByRef InterfaceClassGuid As System.Guid, ByVal MemberIndex As UInteger, ByRef DeviceInterfaceData As SP_DEVICE_INTERFACE_DATA) As Boolean Public Declare Auto Function SetupDiGetDeviceInterfaceDetailBuffer Lib "setupapi.dll" Alias "SetupDiGetDeviceInterfaceDetail" (ByVal DeviceInfoSet As IntPtr, ByRef DeviceInterfaceData As SP_DEVICE_INTERFACE_DATA, ByVal DeviceInterfaceDetailData As IntPtr, ByVal DeviceInterfaceDetailDataSize As Integer, ByRef RequiredSize As Integer, ByRef DeviceInfoData As IntPtr) As Boolean Public Declare Auto Function SetupDiGetDeviceInterfaceDetail Lib "setupapi.dll" (ByVal DeviceInfoSet As IntPtr, ByRef DeviceInterfaceData As SP_DEVICE_INTERFACE_DATA, ByRef DeviceInterfaceDetailData As SP_DEVICE_INTERFACE_DETAIL_DATA, ByVal DeviceInterfaceDetailDataSize As Integer, ByRef RequiredSize As Integer, ByRef DeviceInfoData As SP_DEVINFO_DATA) As Boolean Public Declare Auto Sub HidD_GetHidGuid Lib "hid.dll" Alias "HidD_GetHidGuid" (ByRef hidGuid As Guid) Public Declare Auto Function HidD_GetAttributes Lib "hid.dll" (hidDeviceObject As IntPtr, ByRef attributes As HIDD_ATTRIBUTES) As Boolean End Class " Alias "SetupDiGetDeviceInterfaceDetail" (ByVal DeviceInfoSet As IntPtr, ByRef DeviceInterfaceData As SP_DEVICE_INTERFACE_DATA, ByVal DeviceInterfaceDetailData As IntPtr, ByVal DeviceInterfaceDetailDataSize As Integer, ByRef RequiredSize As Integer, ByRef DeviceInfoData As IntPtr) As Boolean Public Class NativeMethods Public Const DIGCF_PRESENT = &H2 Public Const DIGCF_DEVICEINTERFACE = &H10 Public Const FILE_FLAG_OVERLAPPED = &H40000000 Public Const FILE_SHARE_READ = 1 Public Const FILE_SHARE_WRITE = 2 Public Const GENERIC_READ = &H80000000 Public Const GENERIC_WRITE = &H40000000 Public Const ACCESS_NONE = 0 Public Const INVALID_HANDLE_VALUE = -1 Public Const OPEN_EXISTING = 3 <StructLayout(LayoutKind.Sequential, CharSet:=CharSet.Auto)> _ Public Structure SP_DEVICE_INTERFACE_DETAIL_DATA Public cbSize As UInt32 <MarshalAs(UnmanagedType.ByValTStr, SizeConst:=256)> _ Public DevicePath As String End Structure Public Structure SP_DEVICE_INTERFACE_DATA Public cbSize As Integer Public InterfaceClassGuid As System.Guid Public Flags As Integer Public Reserved As UIntPtr End Structure Public Structure SP_DEVINFO_DATA Public cbSize As Integer Public ClassGuid As System.Guid Public DevInst As Integer Public Reserved As UIntPtr End Structure Public Const HIDP_INPUT = 0 Public Const HIDP_OUTPUT = 1 Public Const HIDP_FEATURE = 2 Public Structure HIDD_ATTRIBUTES Public cbSize As Integer Public VendorID As UShort Public ProductID As UShort Public VersionNumber As Short End Structure Public Structure SECURITY_ATTRIBUTES Public nLength As Integer Public lpSecurityDescriptor As IntPtr Public bInheritHandle As Boolean End Structure Public Declare Auto Function CreateFile Lib "kernel32.dll" (lpFileName As String, dwDesiredAccess As Integer, dwShareMode As Integer, ByRef lpSecurityAttributes As SECURITY_ATTRIBUTES, dwCreationDisposition As Integer, dwFlagsAndAttributes As Integer, hTemplateFile As Integer) As IntPtr Public Declare Auto Function ReadFile Lib "kernel32.dll" (ByVal hFile As IntPtr, ByVal Buffer As IntPtr, ByVal nNumberOfBytesToRead As Integer, ByRef lpNumberOfBytesRead As Integer, ByVal Overlapped As IntPtr) As Integer Public Declare Auto Function CloseHandle Lib "kernel32.dll" (hObject As IntPtr) As Boolean Public Declare Auto Function SetupDiGetClassDevs Lib "setupapi.dll" (ByRef ClassGuid As System.Guid, ByVal Enumerator As Integer, ByVal hwndParent As IntPtr, ByVal Flags As Integer) As IntPtr Public Declare Auto Function SetupDiDestroyDeviceInfoList Lib "setupapi.dll" (deviceInfoSet As IntPtr) As Boolean Public Declare Auto Function SetupDiEnumDeviceInfo Lib "setupapi.dll" (ByVal DeviceInfoSet As Integer, ByVal MemberIndex As Integer, ByRef DeviceInfoData As SP_DEVINFO_DATA) As Boolean Public Declare Auto Function SetupDiEnumDeviceInterfaces Lib "setupapi.dll" (ByVal DeviceInfoSet As IntPtr, ByRef DeviceInfoData As SP_DEVINFO_DATA, ByRef InterfaceClassGuid As System.Guid, ByVal MemberIndex As UInteger, ByRef DeviceInterfaceData As SP_DEVICE_INTERFACE_DATA) As Boolean Public Declare Auto Function SetupDiGetDeviceInterfaceDetailBuffer Lib "setupapi.dll" Alias "SetupDiGetDeviceInterfaceDetail" (ByVal DeviceInfoSet As IntPtr, ByRef DeviceInterfaceData As SP_DEVICE_INTERFACE_DATA, ByVal DeviceInterfaceDetailData As IntPtr, ByVal DeviceInterfaceDetailDataSize As Integer, ByRef RequiredSize As Integer, ByRef DeviceInfoData As IntPtr) As Boolean Public Declare Auto Function SetupDiGetDeviceInterfaceDetail Lib "setupapi.dll" (ByVal DeviceInfoSet As IntPtr, ByRef DeviceInterfaceData As SP_DEVICE_INTERFACE_DATA, ByRef DeviceInterfaceDetailData As SP_DEVICE_INTERFACE_DETAIL_DATA, ByVal DeviceInterfaceDetailDataSize As Integer, ByRef RequiredSize As Integer, ByRef DeviceInfoData As SP_DEVINFO_DATA) As Boolean Public Declare Auto Sub HidD_GetHidGuid Lib "hid.dll" Alias "HidD_GetHidGuid" (ByRef hidGuid As Guid) Public Declare Auto Function HidD_GetAttributes Lib "hid.dll" (hidDeviceObject As IntPtr, ByRef attributes As HIDD_ATTRIBUTES) As Boolean End Class " (ByVal DeviceInfoSet As IntPtr, ByRef DeviceInterfaceData As SP_DEVICE_INTERFACE_DATA, ByRef DeviceInterfaceDetailData As SP_DEVICE_INTERFACE_DETAIL_DATA, ByVal DeviceInterfaceDetailDataSize As Integer, ByRef RequiredSize As Integer, ByRef DeviceInfoData As SP_DEVINFO_DATA) As Boolean Public Class NativeMethods Public Const DIGCF_PRESENT = &H2 Public Const DIGCF_DEVICEINTERFACE = &H10 Public Const FILE_FLAG_OVERLAPPED = &H40000000 Public Const FILE_SHARE_READ = 1 Public Const FILE_SHARE_WRITE = 2 Public Const GENERIC_READ = &H80000000 Public Const GENERIC_WRITE = &H40000000 Public Const ACCESS_NONE = 0 Public Const INVALID_HANDLE_VALUE = -1 Public Const OPEN_EXISTING = 3 <StructLayout(LayoutKind.Sequential, CharSet:=CharSet.Auto)> _ Public Structure SP_DEVICE_INTERFACE_DETAIL_DATA Public cbSize As UInt32 <MarshalAs(UnmanagedType.ByValTStr, SizeConst:=256)> _ Public DevicePath As String End Structure Public Structure SP_DEVICE_INTERFACE_DATA Public cbSize As Integer Public InterfaceClassGuid As System.Guid Public Flags As Integer Public Reserved As UIntPtr End Structure Public Structure SP_DEVINFO_DATA Public cbSize As Integer Public ClassGuid As System.Guid Public DevInst As Integer Public Reserved As UIntPtr End Structure Public Const HIDP_INPUT = 0 Public Const HIDP_OUTPUT = 1 Public Const HIDP_FEATURE = 2 Public Structure HIDD_ATTRIBUTES Public cbSize As Integer Public VendorID As UShort Public ProductID As UShort Public VersionNumber As Short End Structure Public Structure SECURITY_ATTRIBUTES Public nLength As Integer Public lpSecurityDescriptor As IntPtr Public bInheritHandle As Boolean End Structure Public Declare Auto Function CreateFile Lib "kernel32.dll" (lpFileName As String, dwDesiredAccess As Integer, dwShareMode As Integer, ByRef lpSecurityAttributes As SECURITY_ATTRIBUTES, dwCreationDisposition As Integer, dwFlagsAndAttributes As Integer, hTemplateFile As Integer) As IntPtr Public Declare Auto Function ReadFile Lib "kernel32.dll" (ByVal hFile As IntPtr, ByVal Buffer As IntPtr, ByVal nNumberOfBytesToRead As Integer, ByRef lpNumberOfBytesRead As Integer, ByVal Overlapped As IntPtr) As Integer Public Declare Auto Function CloseHandle Lib "kernel32.dll" (hObject As IntPtr) As Boolean Public Declare Auto Function SetupDiGetClassDevs Lib "setupapi.dll" (ByRef ClassGuid As System.Guid, ByVal Enumerator As Integer, ByVal hwndParent As IntPtr, ByVal Flags As Integer) As IntPtr Public Declare Auto Function SetupDiDestroyDeviceInfoList Lib "setupapi.dll" (deviceInfoSet As IntPtr) As Boolean Public Declare Auto Function SetupDiEnumDeviceInfo Lib "setupapi.dll" (ByVal DeviceInfoSet As Integer, ByVal MemberIndex As Integer, ByRef DeviceInfoData As SP_DEVINFO_DATA) As Boolean Public Declare Auto Function SetupDiEnumDeviceInterfaces Lib "setupapi.dll" (ByVal DeviceInfoSet As IntPtr, ByRef DeviceInfoData As SP_DEVINFO_DATA, ByRef InterfaceClassGuid As System.Guid, ByVal MemberIndex As UInteger, ByRef DeviceInterfaceData As SP_DEVICE_INTERFACE_DATA) As Boolean Public Declare Auto Function SetupDiGetDeviceInterfaceDetailBuffer Lib "setupapi.dll" Alias "SetupDiGetDeviceInterfaceDetail" (ByVal DeviceInfoSet As IntPtr, ByRef DeviceInterfaceData As SP_DEVICE_INTERFACE_DATA, ByVal DeviceInterfaceDetailData As IntPtr, ByVal DeviceInterfaceDetailDataSize As Integer, ByRef RequiredSize As Integer, ByRef DeviceInfoData As IntPtr) As Boolean Public Declare Auto Function SetupDiGetDeviceInterfaceDetail Lib "setupapi.dll" (ByVal DeviceInfoSet As IntPtr, ByRef DeviceInterfaceData As SP_DEVICE_INTERFACE_DATA, ByRef DeviceInterfaceDetailData As SP_DEVICE_INTERFACE_DETAIL_DATA, ByVal DeviceInterfaceDetailDataSize As Integer, ByRef RequiredSize As Integer, ByRef DeviceInfoData As SP_DEVINFO_DATA) As Boolean Public Declare Auto Sub HidD_GetHidGuid Lib "hid.dll" Alias "HidD_GetHidGuid" (ByRef hidGuid As Guid) Public Declare Auto Function HidD_GetAttributes Lib "hid.dll" (hidDeviceObject As IntPtr, ByRef attributes As HIDD_ATTRIBUTES) As Boolean End Class ScaleReader.vb
Public Class ScaleReader Private Const VendorId = &HEB8 ' 0EB8 = Toledo, see http://usb-ids.gowdy.us/read/UD/ Private Const ProductId = &HF000 ' F000 = PS60 ' Scale status enumeration Public Enum ScaleStatus Fault StableAtZero InMotion WeightStable UnderZero OverWeight RequiresCalibration RequiresRezeroing RequiresGEO Unknown End Enum ' Scale weighing unit Public Enum WeightUnit UnitMilligram UnitGram UnitKilogram UnitCarats UnitTaels UnitGrains UnitPennyweights UnitMetricTon UnitAvoirTon UnitTroyOunce UnitOunce UnitPound UnitUnknown End Enum ' Scale measure report Public Structure ScaleReport Public ReportId As UShort ' Scale report id Public Status As ScaleStatus ' Scale status Public Unit As WeightUnit ' Weighing unit Public Scaling As SByte ' Scaling, power of 10 Public WeightLsb As UShort ' Least-significant byte of weight value Public WeightMsb As UShort ' Most-significant byte of weight value Public ErrorCode As Integer ' Error code ' Calculates weight from LSB, MSB and scaling Public Function GetWeight() As Double GetWeight = (WeightMsb * 256 + WeightLsb) * (10 ^ Scaling) End Function End Structure Private ioHandle As IntPtr ' handle to read from device ' Opens device with desired access rights Private Function OpenDeviceIO(devicePath As String, deviceAccess As Integer) As IntPtr Dim security As NativeMethods.SECURITY_ATTRIBUTES security.lpSecurityDescriptor = IntPtr.Zero security.bInheritHandle = True security.nLength = Marshal.SizeOf(security) OpenDeviceIO = NativeMethods.CreateFile(devicePath, deviceAccess, NativeMethods.FILE_SHARE_READ + NativeMethods.FILE_SHARE_WRITE, security, NativeMethods.OPEN_EXISTING, 0, 0) End Function ' Close previously opened device Private Sub CloseDeviceIO(handle As IntPtr) NativeMethods.CloseHandle(handle) End Sub ' Disconnect from scale Public Sub Disconnect() CloseDeviceIO(ioHandle) End Sub ' Find Toledo PS60 scale and open to read weight values Public Function Connect() As Boolean Dim hidClass As Guid NativeMethods.HidD_GetHidGuid(hidClass) ' Obtain hid device class Guid to enumerate all hid devices Dim DeviceInfoSet As IntPtr Dim DeviceInfoData As NativeMethods.SP_DEVINFO_DATA Dim DeviceInterfaceData As NativeMethods.SP_DEVICE_INTERFACE_DATA Dim DeviceInterfaceDetailData As NativeMethods.SP_DEVICE_INTERFACE_DETAIL_DATA = Nothing Dim RequiredSize As Integer Dim success As Boolean DeviceInfoSet = NativeMethods.SetupDiGetClassDevs(hidClass, IntPtr.Zero, 0, NativeMethods.DIGCF_PRESENT + NativeMethods.DIGCF_DEVICEINTERFACE) ' Open hid device enumeration DeviceInterfaceData.cbSize = Marshal.SizeOf(DeviceInterfaceData) DeviceInterfaceDetailData.cbSize = 6 DeviceInfoData.cbSize = Marshal.SizeOf(DeviceInfoData) Dim deviceIndex As Integer ' Current deviec index deviceIndex = 0 Do While NativeMethods.SetupDiEnumDeviceInfo(DeviceInfoSet, deviceIndex, DeviceInfoData) ' Loop through all hid devices Dim deviceIfaceIndex As Integer ' Device interface index deviceIfaceIndex = 0 Do While NativeMethods.SetupDiEnumDeviceInterfaces(DeviceInfoSet, DeviceInfoData, hidClass, deviceIfaceIndex, DeviceInterfaceData) ' Loop through all interfaces of current device success = NativeMethods.SetupDiGetDeviceInterfaceDetailBuffer(DeviceInfoSet, DeviceInterfaceData, IntPtr.Zero, 0, RequiredSize, IntPtr.Zero) ' Obtain buffer size success = NativeMethods.SetupDiGetDeviceInterfaceDetail(DeviceInfoSet, DeviceInterfaceData, DeviceInterfaceDetailData, RequiredSize, RequiredSize, DeviceInfoData) ' Get device information using previously recieved buffer size Dim hidHandle As IntPtr hidHandle = OpenDeviceIO(DeviceInterfaceDetailData.DevicePath, NativeMethods.ACCESS_NONE) ' Open device with no access rights to get pid&vid If hidHandle <> NativeMethods.INVALID_HANDLE_VALUE Then Dim deviceAttributes As NativeMethods.HIDD_ATTRIBUTES deviceAttributes.cbSize = Marshal.SizeOf(deviceAttributes) success = NativeMethods.HidD_GetAttributes(hidHandle, deviceAttributes) ' Read device attributes, including PID, VID and Version If success And deviceAttributes.VendorID = VendorId And deviceAttributes.ProductID = ProductId Then ' If it matches Toledo PS60 CloseDeviceIO(hidHandle) ' Close device ioHandle = OpenDeviceIO(DeviceInterfaceDetailData.DevicePath, NativeMethods.GENERIC_READ) ' And reopen with access rights to read reports NativeMethods.SetupDiDestroyDeviceInfoList(DeviceInfoSet) ' Close enumeration Connect = True Exit Function End If CloseDeviceIO(hidHandle) End If deviceIfaceIndex = deviceIfaceIndex + 1 Loop deviceIndex = deviceIndex + 1 Loop NativeMethods.SetupDiDestroyDeviceInfoList(DeviceInfoSet) ' Close enumeration Connect = False End Function ' Reads current weight from scale Public Function ReadValue() As ScaleReport Dim bytesRead As Integer Dim buffer(10) As Byte Dim bufPtr As IntPtr bufPtr = Marshal.AllocHGlobal(10) ' Allocate 10 bytes for report ReadValue = Nothing Dim res As Integer res = NativeMethods.ReadFile(ioHandle, bufPtr, 10, bytesRead, IntPtr.Zero) ' Read 10 bytes from scale If res > 0 Then ' 0=Failure, any positive is success Marshal.Copy(bufPtr, buffer, 0, 10) ' Copy unmamanged buffer to managed byte array If bytesRead < 6 Then ' Report must be 6 bytes or greater (for compatibility) ReadValue.Status = ScaleStatus.Fault Marshal.FreeHGlobal(bufPtr) Exit Function End If Dim rep As ScaleReport rep.ReportId = buffer(0) ' byte #0 is report id Select Case buffer(1) ' byte #1 is scale status Case &H1 rep.Status = ScaleStatus.Fault Case &H2 rep.Status = ScaleStatus.StableAtZero Case &H3 rep.Status = ScaleStatus.InMotion Case &H4 rep.Status = ScaleStatus.WeightStable Case &H5 rep.Status = ScaleStatus.UnderZero Case &H6 rep.Status = ScaleStatus.OverWeight Case &H7 rep.Status = ScaleStatus.RequiresCalibration Case &H8 rep.Status = ScaleStatus.RequiresRezeroing Case &H9 rep.Status = ScaleStatus.RequiresGEO Case Else rep.Status = ScaleStatus.Unknown End Select Select Case buffer(2) ' byte #2 is scale unit Case &H1 rep.Unit = WeightUnit.UnitMilligram Case &H2 rep.Unit = WeightUnit.UnitGram Case &H3 rep.Unit = WeightUnit.UnitKilogram Case &H4 rep.Unit = WeightUnit.UnitCarats Case &H5 rep.Unit = WeightUnit.UnitTaels Case &H6 rep.Unit = WeightUnit.UnitGrains Case &H7 rep.Unit = WeightUnit.UnitPennyweights Case &H8 rep.Unit = WeightUnit.UnitMetricTon Case &H9 rep.Unit = WeightUnit.UnitAvoirTon Case &HA rep.Unit = WeightUnit.UnitTroyOunce Case &HB rep.Unit = WeightUnit.UnitOunce Case &HC rep.Unit = WeightUnit.UnitPound Case Else rep.Unit = WeightUnit.UnitUnknown End Select rep.Scaling = IIf(buffer(3) < 128, buffer(3), buffer(3) - 256) ' byte #3 is scaling rep.WeightLsb = buffer(4) ' byte #4 is LSB rep.WeightMsb = buffer(5) ' byte #5 is MSB ReadValue = rep Else Dim err = Marshal.GetLastWin32Error ReadValue.Status = ScaleStatus.Fault ReadValue.ErrorCode = err End If Marshal.FreeHGlobal(bufPtr) End Function End Class Source: https://habr.com/ru/post/205462/
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