We Keep Coding

C# Modbus: ReadHoldingRegisters not consistent in returning ouput

I'm trying to search for a modbus that is connected to a serial port on my device and run some commands against it. However it seems to be that it is rather inconsistent at reading the holding registers. I'm using the NModbus4 library.
I have a thread running every second that checks for available serial ports and tries to get a connection:
// === Check if port is open, start connecting procedure if closed
if (!(serialPort.IsOpen))
{
List<string> portnames = new List<string>();
foreach (string s in SerialPort.GetPortNames())
{
portnames.Add(s); // COM3
}
// === Loop through the listed ports and try to connect
foreach (string portname in portnames)
{
if (!(serialPort.IsOpen))
{
try
{
serialPort.PortName = portname;
serialPort.BaudRate = 57600;
serialPort.DataBits = 8;
serialPort.Parity = Parity.None;
serialPort.StopBits = StopBits.Two;
serialPort.Open();
}
catch (Exception e)
{
Console.WriteLine(e.Message);
}
}
}
}
// === Check again after connecting procedure if the port is open
if (serialPort.IsOpen)
{
// === Check number of open ports
if (SerialPort.GetPortNames().Count() != 0)
{
// === Check if master is defined
if (master == null)
{
// === Define master
master = ModbusSerialMaster.CreateRtu(serialPort);
}
// === If master is already defined
if (master != null)
{
int parameterID = this.readParameterSetID();
if (parameterID != 0)
{
if (!desk_devices.Contains(parameterID))
{
desk_devices.Add(parameterID);
newDevice = true;
}
}
}
} else
{
// === No serial ports available, close the opened serial port
serialPort.Close();
}
}
The readParameterSetID function is as following:
private int readParameterSetID()
{
int parameterSetID = 0;
if (mutex)
{
Console.WriteLine("---Poll overrun----");
}
mutex = true;
if (serialPort.IsOpen)
{
if (master != null)
{
try
{
ushort[] holding_register = master.ReadHoldingRegisters(1, 107, 1); // Fails here
for (int i = 0; i < 1; i++)
{
int tmpStart = Convert.ToInt32(107 + i);
String tempStart = Convert.ToString(tmpStart, 16);
int tmpReg = Convert.ToInt32(holding_register[i]);
String tempReg = Convert.ToString(tmpReg, 16);
parameterSetID = holding_register[i];
}
} catch (Exception e)
{
Console.WriteLine(e.Message);
}
}
}
mutex = false;
return parameterSetID;
}
Now the weird thing happening here is that the readParameterSetID function should return a 7 or a 0 when executed correctly. However sometimes it just stops after reading the holding registers. mutex will stay true and nothing gets returned. When I reboot the application it either works or the same thing happens again.
I don't know why it's working in 50% of the situations and the other 50% returns nothing. I've tried to redefine the master if the function readParameterSetID fails, however I noticed that once every couple second the master will be reset resulting in commands further down the line not being send.
I'd love to know why this is happening or a way to fix this and read the holding registers without the communication failing.

Windows IOT UWP - Relay

Good Evening,
I’m doing some troubleshooting on the beginning of my home automation system. I am trying to toggle a relay using a Raspberry PI 3 and Windows IOT in C#. I’ve been playing with the code and I can see the relay toggle once or twice, but then the app crashes. I’m an IOT Noob, so is there something wrong with this code? (Variable names are defined elsewhere and the weird variable names I have below are for my WIP project... I prefer troubleshooting in English)....
private void BtnTempFan_Click(object sender, RoutedEventArgs e)
{
if (BtnTempFan.IsChecked == true)
{
TogglePin(TempFan, TempFan_PIN, BtnTempFan, GpioPinValue.High);
}
else
{
TempFan.Dispose();
}
}
private void TogglePin(GpioPin PinName, int PinNumber, ToggleButton Name, GpioPinValue value)
{
int pinnumber = PinNumber;
GpioPinValue pinvalue;
var gpio = GpioController.GetDefault();
PinName = gpio.OpenPin(pinnumber);
if (gpio == null)
{
PinName = null;
LblError.Text = "We can't find the controller on the device" + PinName;
LblError.Visibility = Visibility.Visible;
return;
}
if (PinName == null)
{
LblError.Text = "We can't find the pin on the device. Pin number " + PinNumber + "does not exist";
LblError.Visibility = Visibility.Visible;
return;
}
if (Name.IsChecked == true)
{
pinvalue = value;
PinName.Write(pinvalue);
PinName.SetDriveMode(GpioPinDriveMode.Output);
}

You don't say what the exception is. However, I believe you are supposed open a GPIO pin only once per app:
var gpio = GpioController.GetDefault();
PinName = gpio.OpenPin(pinnumber);
You have it in a method which is called once per button click. By opening the pin more than once, you are encountering that the pin is already open, and I believe this is what throws an exception and crashes the app.
In my code, I handle pin states in a "driver" class, and have a method called Connect which I call once when starting the application. For example:
public async Task Connect()
{
var gpioController = await GpioController.GetDefaultAsync();
try
{
_openPin = gpioController.OpenPin(_doorMotorOpenPin);
_closePin = gpioController.OpenPin(_doorMotorClosePin);
}
}
This encapsulates the 2 pins: _openPin and _closePin into a class that I can manage the lifecycle of.

Codekaizen is correct. I separated out opening the pin into a method that only gets called once and problem solved.
private void BtnTempFan_Click(object sender, RoutedEventArgs e)
{
if (BtnTempFan.IsChecked == false)
{
TogglePin(TempFan, TempFan_PIN, BtnTempFan, GpioPinValue.High);
}
if (BtnTempFan.IsChecked == true)
{
TogglePin(TempFan, TempFan_PIN, BtnTempFan, GpioPinValue.Low);
}
}
private void InitializePins()
{
var gpio = GpioController.GetDefault();
// Show an error if there is no GPIO controller
if (gpio == null)
{
TempFan = null;
LblError.Text = "We can't find the controller on the device";
LblError.Visibility = Visibility.Visible;
return;
}
TempFan = gpio.OpenPin(TempFan_PIN);
TempFan.SetDriveMode(GpioPinDriveMode.Output);
}
private void TogglePin(GpioPin PinName, int PinNumber, ToggleButton Name, GpioPinValue value)
{
int pinnumber = PinNumber;
GpioPinValue pinvalue;
pinvalue = value;
PinName.Write(pinvalue);
}

Why value does not fall within the expected range when setting Value Changed for Gatt Characteristic

I would like to keep on reading characteristic/set value changed event handlers for characteristics from my BLE 4.0 device, by using the ValueChanged callback in Universal Windows Platform C# in Visual Studio 2017.
I followed some tutorial from these sites: Damian Blog's Windows Universal with BLE, Bluetooth Gatt's Git Hub, Bluetooth Generic Attribute Profile - Heart Rate Service and Dr. Jukka's mobile Blog on BLE. All of them are using ValueChanged and I have tried to follow what they did.
Unfortunately, instead of ValueChanged being triggered, I receive the following error when using the ValueChanged callback.
System.ArgumentException: 'Value does not fall within the expected range.'
This line of code is producing the error:
characteristic.ValueChanged += Oncharacteristic_ValueChanged;
Here is more details of my source code:
NOTE: I am using COM 7 for my dongler and my program could discover the BLE's device name, and could discover the Uuid of the services and characteristics.
public List<string> serviceList = new List<string>();
public List<string> characteristicList = new List<string>();
public BluetoothLEDevice myDevice { get; set; }
public MainPage()
{
this.InitializeComponent();
}
private async void Page_Loaded(object sender, RoutedEventArgs e)
{
// Find the com port
string selector = SerialDevice.GetDeviceSelector("COM7");
DeviceInformationCollection devices = await DeviceInformation.FindAllAsync(selector);
if (devices.Count > 0)
{
var dialog = new MessageDialog("Com Device found");
await dialog.ShowAsync();
DeviceInformation deviceInfo = devices[0];
SerialDevice serialDevice = await SerialDevice.FromIdAsync(deviceInfo.Id);
serialDevice.BaudRate = 9600;
serialDevice.DataBits = 8;
serialDevice.StopBits = SerialStopBitCount.One;
serialDevice.Parity = SerialParity.None;
}
else
{
MessageDialog popup = new MessageDialog("Sorry, no device found.");
await popup.ShowAsync();
}
// After com port is found, search for device
foreach (DeviceInformation di in await DeviceInformation.FindAllAsync(BluetoothLEDevice.GetDeviceSelector()))
{
BluetoothLEDevice bleDevice = await BluetoothLEDevice.FromIdAsync(di.Id);
// Display BLE device name
var dialogBleDeviceName = new MessageDialog("BLE Device Name " + bleDevice.Name);
await dialogBleDeviceName.ShowAsync();
myDevice = bleDevice;
}
// Check device connection
myDevice.ConnectionStatusChanged += OnConnectionStatusChanged;
foreach (var service in myDevice.GattServices)
{
serviceList.Add(service.Uuid.ToString());
// Verify if service is discovered by displaying a popup
MessageDialog serviceUuidPopUp = new MessageDialog("Adding Service Uuid to list " + service.Uuid.ToString() );
await serviceUuidPopUp.ShowAsync();
foreach (var characteristic in service.GetAllCharacteristics())
{
var characteristicUuid = characteristic.Uuid.ToString().ToLowerInvariant();
characteristicList.Add(characteristicUuid);
// Verify if characteristic is discovered by displaying a popup
MessageDialog charUuidPopUp = new MessageDialog("Adding characteristic Uuid to list " + characteristicUuid);
await charUuidPopUp.ShowAsync();
// set value changed event handlers for characteristics
characteristic.ValueChanged += Oncharacteristic_ValueChanged;
}
}
}
private void OnConnectionStatusChanged(BluetoothLEDevice sender, object args)
{
if (sender.ConnectionStatus == BluetoothConnectionStatus.Connected)
{
System.Diagnostics.Debug.WriteLine("Connected");
}
else
{
System.Diagnostics.Debug.WriteLine("Disconnected");
}
}
private void Oncharacteristic_ValueChanged(GattCharacteristic sender, GattValueChangedEventArgs args)
{
byte[] data = new byte[args.CharacteristicValue.Length];
DataReader.FromBuffer(
args.CharacteristicValue).ReadBytes(data);
string text = Encoding.UTF8.GetString(data, 0, data.Length);
}
UPDATE 1
I tried to check Characteristic Properties before set value changed event handlers for my characteristics by following the answer given by rudi belt on SO.
if (characteristic.CharacteristicProperties == (GattCharacteristicProperties.Read | GattCharacteristicProperties.Notify))
{
characteristic.ValueChanged += Oncharacteristic_ValueChanged;
}
Unfortunately, this IF statement is not executed.
UPDATE 2
I have tried to remove ALL the codes inside Oncharacteristic_ValueChanged method. But it still gives me the same error
System.ArgumentException: 'Value does not fall within the expected range.'
I have been spending a lot of time trying to solve this problem. I will be very happy if anyone can help me on this. Thank you!

Reading your efforts in the former question I can provide a working example, but first some explanation.
myDevice.ConnectionStatusChanged is not needed, it is only used to notice a connection is lost or connected. You have to connect to your device first and handle things in the connection method.
After you have succeeded in connecting you have to get the service that contains the characteristic you want to use for read, write, notify or indicate.
When you have selected the service You can get the characteristics of that service.
Select the characteristic by Uuid, or in my example with CharacteristicProperties.HasFlag.
This flag in my example is Notify.
In the code comments you find extra info.
using System;
using System.Diagnostics;
using System.Threading.Tasks;
using Windows.Devices.Bluetooth;
using Windows.Devices.Bluetooth.GenericAttributeProfile;
using Windows.Devices.Enumeration;
using Windows.UI.Popups;
using Windows.UI.Xaml.Controls;
namespace App1
{
public sealed partial class MainPage : Page
{
GattDeviceServicesResult serviceResult = null;
private BluetoothLEDevice myDevice;
private GattCharacteristic selectedCharacteristic;
public MainPage()
{
this.InitializeComponent();
ConnectDevice();
}
private async void ConnectDevice()
{
//This works only if your device is already paired!
foreach (DeviceInformation di in await DeviceInformation.FindAllAsync(BluetoothLEDevice.GetDeviceSelector()))
{
BluetoothLEDevice bleDevice = await BluetoothLEDevice.FromIdAsync(di.Id);
// Display BLE device name
var dialogBleDeviceName = new MessageDialog("BLE Device Name " + bleDevice.Name);
await dialogBleDeviceName.ShowAsync();
myDevice = bleDevice;
}
if (myDevice != null)
{
int servicesCount = 3;//Fill in the amount of services from your device!!!!!
int tryCount = 0;
bool connected = false;
while (!connected)//This is to make sure all services are found.
{
tryCount++;
serviceResult = await myDevice.GetGattServicesAsync();
if (serviceResult.Status == GattCommunicationStatus.Success && serviceResult.Services.Count >= servicesCount)
{
connected = true;
Debug.WriteLine("Connected in " + tryCount + " tries");
}
if (tryCount > 5)//make this larger if faild
{
Debug.WriteLine("Failed to connect to device ");
return;
}
}
if (connected)
{
for (int i = 0; i < serviceResult.Services.Count; i++)
{
var service = serviceResult.Services[i];
//This must be the service that contains the Gatt-Characteristic you want to read from or write to !!!!!!!.
string myServiceUuid = "0000ffe0-0000-1000-8000-00805f9b34fb";
if (service.Uuid.ToString() == myServiceUuid)
{
Get_Characteriisics(service);
break;
}
}
}
}
}
private async void Get_Characteriisics(GattDeviceService myService)
{
var CharResult = await myService.GetCharacteristicsAsync();
if (CharResult.Status == GattCommunicationStatus.Success)
{
foreach (GattCharacteristic c in CharResult.Characteristics)
{
if (c.CharacteristicProperties.HasFlag(GattCharacteristicProperties.Notify))
{
selectedCharacteristic = c;
break;
}
}
try
{
// Write the ClientCharacteristicConfigurationDescriptor in order for server to send notifications.
var result = await selectedCharacteristic.WriteClientCharacteristicConfigurationDescriptorAsync(
GattClientCharacteristicConfigurationDescriptorValue.Notify);
if (result == GattCommunicationStatus.Success)
{
var dialogNotifications = new MessageDialog("Successfully registered for notifications");
await dialogNotifications.ShowAsync();
selectedCharacteristic.ValueChanged += SelectedCharacteristic_ValueChanged;
}
else
{
var dialogNotifications = new MessageDialog($"Error registering for notifications: {result}");
await dialogNotifications.ShowAsync();
}
}
catch (Exception ex)
{
// This usually happens when not all characteristics are found
// or selected characteristic has no Notify.
var dialogNotifications = new MessageDialog(ex.Message);
await dialogNotifications.ShowAsync();
await Task.Delay(100);
Get_Characteriisics(myService); //try again
//!!! Add a max try counter to prevent infinite loop!!!!!!!
}
}
else
{
var dialogNotifications = new MessageDialog("Restricted service. Can't read characteristics");
await dialogNotifications.ShowAsync();
}
}
private void SelectedCharacteristic_ValueChanged(GattCharacteristic sender, GattValueChangedEventArgs args)
{
}
}
}
If you have problems with this code feel free to ask in comments.

Restarting nodejs as a process in C#

I am starting NodeJs as a process inside a C# application. My intent is to restart the process every time it stops.
Code for starting the process is:
_nodeProcess = new Process
{
StartInfo =
{
UseShellExecute = false,
RedirectStandardOutput = true,
RedirectStandardError = true,
RedirectStandardInput = true,
WorkingDirectory = location,
FileName = "node.exe",
Arguments = "main.js"
}
};
_nodeProcess.EnableRaisingEvents = true;
_nodeProcess.Exited += nodeExited;
_nodeProcess.Start();
string stderrStr = _nodeProcess.StandardError.ReadToEnd();
string stdoutStr = _nodeProcess.StandardOutput.ReadToEnd();
if (!String.IsNullOrWhiteSpace(stderrStr))
{
LogInfoMessage(stderrStr);
}
LogInfoMessage(stdoutStr);
_nodeProcess.WaitForExit();
_nodeProcess.Close();
here is nodeExited method:
private void nodeExited(object sender, EventArgs e)
{
if (!_isNodeStop)
{
this.restartERM_Click(sender, e);
}
else
{
_isNodeStop = false;
}
}
_isNodeStop is just a flag that I set to true when killing a node from the controlled place.
Like this:
private void KillNode()
{
foreach (var process in Process.GetProcessesByName("node"))
{
_isNodeStop = true;
process.Kill();
}
}
My problem is that nodeExited method does not trigger every time node is stopped. I have no clue why and I could not see any pattern. Is just does not stop most of the times.

You are using WaitForExit() anyway, so there is no reason to use the Exited event.
Just manually call your Handler after WaitForExit() like this:
_nodeProcess.WaitForExit();
_nodeProcess.Close();
nodeExited(_nodeProcess, new EventArgs());
and remove
_nodeProcess.EnableRaisingEvents = true;
_nodeProcess.Exited += nodeExited;
Edit:
If I understand this answer correctly, you might also have a deadlock because you call StandardError.ReadToEnd(); and then StandardOutput.ReadToEnd();. The StandardOutput Buffer might be full before it even reaches that point.

Redirect Standard Output Efficiently in .NET

I am trying to call php-cgi.exe from a .NET program. I use RedirectStandardOutput to get the output back as a stream but the whole thing is very slow.
Do you have any idea on how I can make that faster? Any other technique?
Dim oCGI As ProcessStartInfo = New ProcessStartInfo()
oCGI.WorkingDirectory = "C:\Program Files\Application\php"
oCGI.FileName = "php-cgi.exe"
oCGI.RedirectStandardOutput = True
oCGI.RedirectStandardInput = True
oCGI.UseShellExecute = False
oCGI.CreateNoWindow = True
Dim oProcess As Process = New Process()
oProcess.StartInfo = oCGI
oProcess.Start()
oProcess.StandardOutput.ReadToEnd()

The best solution I have found is:
private void Redirect(StreamReader input, TextBox output)
{
new Thread(a =>
{
var buffer = new char[1];
while (input.Read(buffer, 0, 1) > 0)
{
output.Dispatcher.Invoke(new Action(delegate
{
output.Text += new string(buffer);
}));
};
}).Start();
}
private void Window_Loaded(object sender, RoutedEventArgs e)
{
process = new Process
{
StartInfo = new ProcessStartInfo
{
CreateNoWindow = true,
FileName = "php-cgi.exe",
RedirectStandardOutput = true,
UseShellExecute = false,
WorkingDirectory = #"C:\Program Files\Application\php",
}
};
if (process.Start())
{
Redirect(process.StandardOutput, textBox1);
}
}

You can use the OutputDataReceived event to receive data as it's pumped to StdOut.

The problem is due a bad php.ini config. I had the same problem and i downloaded the Windows installer from: http://windows.php.net/download/.
After that and commenting out not needed extensions, the conversion process is alà Speedy Gonzales, converting 20 php per second.
You can safely use "oProcess.StandardOutput.ReadToEnd()". It's more readable and alomost as fast as using the thread solution. To use the thread solution in conjunction with a string you need to introduce an event or something.
Cheers