C#•17mo ago

✅ Can you lock or freeze a thread while using another form in a new thread??

Part of my application requires i detect a USB device, and grab the DeviceID, I've got this and works fine, how ever im trying to get it to open a new form when it detects that the device is connected. again i got this working. the issue i got is i want it open a form and pass in a serial number from the USB. again i got this working but had to open the form by spawning a new thread. however dispite the form being open as Showdialog(), i can still access the main form. im assuming this is because they are on 2 separate threads. am i able to lock the previous thread while i have the new form open ??? and when it closes unlock it? this is my code for opening the form currently

 private void DeviceInsertedEvent(object sender, EventArrivedEventArgs e)
        {
            // Update Interface to recognise USB inserted
            lblUSBDetection.Text = "-- USB Inserted";

            string serialNumber;

            // Retrieve Serial Number from USB Device
            ManagementBaseObject instance = (ManagementBaseObject)e.NewEvent["TargetInstance"];

            foreach (var s in instance.Properties)
            {
                //Output all properties and values to debug console window for testing
                //Debug.WriteLine(s.Name + " = " + s.Value);

                if (s.Name == "PNPDeviceID")
                {
                    string[] strings = s.Value.ToString().Split('\\');
                    serialNumber = strings[2];
                    Debug.WriteLine(serialNumber);
  
                    if (serialNumber != null)
                    {
                        //TODO if staement to show form  if Serial matches serial stored in the data base, for now open form for all USB devices
                        new Thread(() => new USBPopup(serialNumber).ShowDialog()).Start();
                    }
                    break;
                }
            }
        }

 private void DeviceInsertedEvent(object sender, EventArrivedEventArgs e)
        {
            // Update Interface to recognise USB inserted
            lblUSBDetection.Text = "-- USB Inserted";

            string serialNumber;

            // Retrieve Serial Number from USB Device
            ManagementBaseObject instance = (ManagementBaseObject)e.NewEvent["TargetInstance"];

            foreach (var s in instance.Properties)
            {
                //Output all properties and values to debug console window for testing
                //Debug.WriteLine(s.Name + " = " + s.Value);

                if (s.Name == "PNPDeviceID")
                {
                    string[] strings = s.Value.ToString().Split('\\');
                    serialNumber = strings[2];
                    Debug.WriteLine(serialNumber);
  
                    if (serialNumber != null)
                    {
                        //TODO if staement to show form  if Serial matches serial stored in the data base, for now open form for all USB devices
                        new Thread(() => new USBPopup(serialNumber).ShowDialog()).Start();
                    }
                    break;
                }
            }
        }

19 Replies

Unknown User•17mo ago

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GibboOP•17mo ago

ok ty, il go have a read up on these

phaseshift•17mo ago

new Thread(() => new USBPopup(serialNumber).ShowDialog()).Start();

aren't you meant to use dispatcher to run/queue thinhgs on the ui thread? https://learn.microsoft.com/en-us/dotnet/api/system.windows.threading.dispatcher.invoke?view=windowsdesktop-7.0

Dispatcher.Invoke Method (System.Windows.Threading)

Executes the specified delegate synchronously on the thread the Dispatcher is associated with.

GibboOP•17mo ago

no idea as I'm a novice, and just learning as i go, I've worked out a way to do this now though with out too much effort

            if (InvokeRequired == true)
            {
                Invoke(new Action(() => { this.Close(); }));
            }
            else
            {
                this.Close();
            }

            if (InvokeRequired == true)
            {
                Invoke(new Action(() => { this.Close(); }));
            }
            else
            {
                this.Close();
            }

Unknown User•17mo ago

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GibboOP•17mo ago

im using winforms i am having another issue if you can help thow

Unknown User•17mo ago

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GibboOP•17mo ago

ive got a usb device but it reports 2 PNPdevice IDs, , i got my code opening and closing a form based on detection and removal but on removal the usb with 2 ids loads a 2nd form been playing for hours no trying to sort it lol

Unknown User•17mo ago

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GibboOP•17mo ago

yea this is a unique device has 2 device IDs il get a video asec

Unknown User•17mo ago

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GibboOP•17mo ago

wrong veideo

Unknown User•17mo ago

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GibboOP•17mo ago

so one usb stick has 2 PNPDeviceID's

GibboOP•17mo ago

Availability = 
Caption = USB Mass Storage Device
ClassCode = 
ConfigManagerErrorCode = 0
ConfigManagerUserConfig = False
CreationClassName = Win32_USBHub
CurrentAlternateSettings = 
CurrentConfigValue = 
Description = USB Mass Storage Device
DeviceID = USB\VID_16D0&PID_0D71&MI_01\8&1D5C76F4&2&0001
ErrorCleared = 
ErrorDescription = 
GangSwitched = 
InstallDate = 
LastErrorCode = 
Name = USB Mass Storage Device
NumberOfConfigs = 
NumberOfPorts = 
PNPDeviceID = USB\VID_16D0&PID_0D71&MI_01\8&1D5C76F4&2&0001
PowerManagementCapabilities = 
PowerManagementSupported = 
ProtocolCode = 
Status = OK
StatusInfo = 
SubclassCode = 
SystemCreationClassName = Win32_ComputerSystem
SystemName = UK-CH-OR-TS9-L
USBVersion = 
Availability = 
Caption = USB Composite Device
ClassCode = 
ConfigManagerErrorCode = 0
ConfigManagerUserConfig = False
CreationClassName = Win32_USBHub
CurrentAlternateSettings = 
CurrentConfigValue = 
Description = USB Composite Device
DeviceID = USB\VID_16D0&PID_0D71\00012547
ErrorCleared = 
ErrorDescription = 
GangSwitched = 
InstallDate = 
LastErrorCode = 
Name = USB Composite Device
NumberOfConfigs = 
NumberOfPorts = 
PNPDeviceID = USB\VID_16D0&PID_0D71\00012547
PowerManagementCapabilities = 
PowerManagementSupported = 
ProtocolCode = 
Status = OK
StatusInfo = 
SubclassCode = 
SystemCreationClassName = Win32_ComputerSystem
SystemName = UK-CH-OR-TS9-L
USBVersion =

Availability = 
Caption = USB Mass Storage Device
ClassCode = 
ConfigManagerErrorCode = 0
ConfigManagerUserConfig = False
CreationClassName = Win32_USBHub
CurrentAlternateSettings = 
CurrentConfigValue = 
Description = USB Mass Storage Device
DeviceID = USB\VID_16D0&PID_0D71&MI_01\8&1D5C76F4&2&0001
ErrorCleared = 
ErrorDescription = 
GangSwitched = 
InstallDate = 
LastErrorCode = 
Name = USB Mass Storage Device
NumberOfConfigs = 
NumberOfPorts = 
PNPDeviceID = USB\VID_16D0&PID_0D71&MI_01\8&1D5C76F4&2&0001
PowerManagementCapabilities = 
PowerManagementSupported = 
ProtocolCode = 
Status = OK
StatusInfo = 
SubclassCode = 
SystemCreationClassName = Win32_ComputerSystem
SystemName = UK-CH-OR-TS9-L
USBVersion = 
Availability = 
Caption = USB Composite Device
ClassCode = 
ConfigManagerErrorCode = 0
ConfigManagerUserConfig = False
CreationClassName = Win32_USBHub
CurrentAlternateSettings = 
CurrentConfigValue = 
Description = USB Composite Device
DeviceID = USB\VID_16D0&PID_0D71\00012547
ErrorCleared = 
ErrorDescription = 
GangSwitched = 
InstallDate = 
LastErrorCode = 
Name = USB Composite Device
NumberOfConfigs = 
NumberOfPorts = 
PNPDeviceID = USB\VID_16D0&PID_0D71\00012547
PowerManagementCapabilities = 
PowerManagementSupported = 
ProtocolCode = 
Status = OK
StatusInfo = 
SubclassCode = 
SystemCreationClassName = Win32_ComputerSystem
SystemName = UK-CH-OR-TS9-L
USBVersion =

Unknown User•17mo ago

Message Not Public

Accord•17mo ago

Was this issue resolved? If so, run /close - otherwise I will mark this as stale and this post will be archived until there is new activity.

GibboOP•17mo ago

what I'm seeing is correct, as i suspect this this is 2 usbs rolled into one. how ever my code should break out of the loop when it finds the first PNPDeviceID, but it doesn't, i get one prompt which im expecting and is successful, then when i remove the usb a 2nd prompt pop s up for the 2nd pnp device

        private void DeviceInsertedEvent(object sender, EventArrivedEventArgs e)
        {
            // Update Interface to recognise USB inserted and get serial number from the device
            //lblUSBDetection.Text = "-- USB Inserted";
            string serialNumber = "";
            string[] fullDeviceID;
            string[] shortDeviceID;

            List<string> list = new List<string>();
            ManagementBaseObject instance = (ManagementBaseObject)e.NewEvent["TargetInstance"];


            if (list.Count != 1)
            {
                foreach (var s in instance.Properties)
                {
                    if (s.Name == "PNPDeviceID")
                    {
                        list.Add(s.Value.ToString());
                        break;
                    }
                }
            }

            fullDeviceID = list.ToArray();
            shortDeviceID = fullDeviceID[0].Split('\\');
            serialNumber = shortDeviceID[2];

            if (serialNumber != null)
            {
                list.Clear();
                Debug.WriteLine("Full Device ID: " + fullDeviceID[0] + "\nShort Device ID: " + serialNumber);
                Form USBPopup = new USBPopup(serialNumber);
                USBPopup.ShowDialog();
            }
        }

        private void DeviceInsertedEvent(object sender, EventArrivedEventArgs e)
        {
            // Update Interface to recognise USB inserted and get serial number from the device
            //lblUSBDetection.Text = "-- USB Inserted";
            string serialNumber = "";
            string[] fullDeviceID;
            string[] shortDeviceID;

            List<string> list = new List<string>();
            ManagementBaseObject instance = (ManagementBaseObject)e.NewEvent["TargetInstance"];


            if (list.Count != 1)
            {
                foreach (var s in instance.Properties)
                {
                    if (s.Name == "PNPDeviceID")
                    {
                        list.Add(s.Value.ToString());
                        break;
                    }
                }
            }

            fullDeviceID = list.ToArray();
            shortDeviceID = fullDeviceID[0].Split('\\');
            serialNumber = shortDeviceID[2];

            if (serialNumber != null)
            {
                list.Clear();
                Debug.WriteLine("Full Device ID: " + fullDeviceID[0] + "\nShort Device ID: " + serialNumber);
                Form USBPopup = new USBPopup(serialNumber);
                USBPopup.ShowDialog();
            }
        }

Accord•16mo ago

Was this issue resolved? If so, run /close - otherwise I will mark this as stale and this post will be archived until there is new activity.

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✅ Can you lock or freeze a thread while using another form in a new thread??