Develop Reference

Serial communication Zebra GC420t - Not receiving

I'm trying to communicate with the GC420t via serial port in c#.
I need to get the status of the printer.
I want to send the command ~HQES and receive the status.
I'm able to write commands: I've tryied to print succesfully some qrcodes.
But when I write the status info command I don't get any answer.
This is my test code:
//define serial port
static SerialPort _serialPort = new SerialPort("COM7", 9600, Parity.None, 8, StopBits.One);
public Serial()
{
try
{
_serialPort.Open();
WriteCommand();
ReadStatus();
}
catch (Exception ex)
{
_serialPort.Close();
}
}
public void WriteCommand()
{
string qrcode = "^XA^FO,20,20^BQ,2,10^FDD03048F,LM,N0123456789,A12AABB,B0006qrcode^FS^XZ";
string statusInfo = " ~HQES";
_serialPort.Write(statusInfo);
}
public void ReadStatus()
{
_serialPort.DataReceived += new SerialDataReceivedEventHandler(DataReceivedHandler);
}
private static void DataReceivedHandler(
object sender,
SerialDataReceivedEventArgs e)
{
SerialPort sp = (SerialPort)sender;
string indata = sp.ReadExisting();
Console.WriteLine("Data Received:");
Console.Write(indata);
}
EDIT:
It will be fine for me also to be able to get that info on request:
WriteCommand();
int timeout = 3000;
while (timeout > 0)
{
Thread.Sleep(10);
timeout--;
// Timeout
string status = _serialPort.ReadExisting();
}

You should check ifs the printer configured to use any form of handshaking? Particularly XON/XOFF or DTR .
Ref page 24 of User Guide. https://www.uline.com/PDF/IH-7246VND.PDF
In the event the link breaks - the relevant text is
"The printer has a DCE serial communication port for hardware compatibility with legacy 888 printers. The required cable must have a nine-pin "D" type (DB-9P) male connector on one end which plugs into the mating (DB-9S) serial port located on the back of the printer. The other end of this signal interface cable connects to a serial port on the host computer. The cable is a Null-Modem (cross-over signal connections) cable. For pinout information, refer to Appendix A.
The serial port communication settings between the printer and host (typically a PC) must match for reliable communication. The Bits per second (or Baud rate) and Flow control are the most common settings that get changed. The host (typically a Windows PC) needs to have the data Flow control changed to match the printer's default communication method: Hardware and is noted by the Host Handshake setting DTR/Xon/Xoff. This combined hardware (DTR) and software (Xon/Xoff) mode may need to change depending{ upon use with non-Zebra application software or the serial cable variation in use."

You need to hook up the DataReceived handler before you make any calls, otherwise it might have answered before you hook it up.
Move ReadStatus up 1 line so that it comes straight after the constructor.
_serialPort.Open();
ReadStatus();
WriteCommand();

UDP packets from a field device will not through azure infrastructure to my service

A field device (Loxone miniserver) is sending measurements in UDP packets to the public adress of an azure VM and to my local machine, both on port 1234(changed for integrity). On my local machine in the same network as the field device I implemented a test receiver in C# which gets the packets correctly.
On an already running application on an azure VM I added the same receiver code as in the local machine and got no UDP packets.
What I already did on the azure management platform:
- Allowed the incoming port 1234 in the network configuration
- Switched off the firewall
For testing I tried following:
- Implemented a UDP sender on the application in the azure VM which sends on broadcast-IP to port 1234 -> this works!
- Added a packet monitor to the network-interface -> here I see both packages, the internal broadcast and the field device
//Receiver-Code reduced to relevant parts
class Program{
public static void Main(string[] args){
program.Run();
}
public void Run(){
var sync = new LoxoneSyncProcess();
while(true){
sync.readUDP();
Thread.sleep(10000);
}
}
}
class LoxoneSyncProcess{
public LoxoneSyncProcess(){
private UDPSocket c = new UDPSocket();
c.Client(1234);
}
public void readUDP(){
String buffer = c.getDatBuf();
Console.WriteLine(buffer);
//process buffer
}
}
public class UDPSocket{
private Socket _socket = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
private const int bufSize = 8 * 1024;
private State state = new State();
private EndPoint epFrom = new IPEndPoint(IPAddress.Any, 0);
private AsyncCallback recv = null;
private String datBuf = "";
public class State
{
public byte[] buffer = new byte[bufSize];
}
public String getDatBuf()
{
String temp = datBuf;
datBuf = "";
return temp;
}
public void Client(int port)
{
_socket.Bind(new IPEndPoint(IPAddress.Any, port));
Receive();
}
private void Receive()
{
_socket.BeginReceiveFrom(state.buffer, 0, bufSize, SocketFlags.None, ref epFrom, recv = (ar) =>
{
State so = (State)ar.AsyncState;
int bytes = _socket.EndReceiveFrom(ar, ref epFrom);
_socket.BeginReceiveFrom(so.buffer, 0, bufSize, SocketFlags.None, ref epFrom, recv, so);
datBuf += Encoding.ASCII.GetString(so.buffer, 0, bytes);
//Console.WriteLine("RECV: {0}: {1}, {2}", epFrom.ToString(), bytes, Encoding.ASCII.GetString(so.buffer, 0, bytes));
}, state);
}
}
The code is working, I receive self sent UDP packets to port 1234 on Broadcast-IP, but not from the field device.
Are there any tables like NAT-configurations needed? Or portforewarding? Does azure support public UDP endpoints?

UDP public Endpoint is supported in Azure. Just wanted to check the size of the UDP payload that you use. If the UDP payload is > 1500 bytes then it will not work.
This is by design at the moment as we do not support fragments to public VIP endpoints right now in the vswitch. The recommendation is for customers to keep UDP datagrams to under 1500. There’s really nothing short term we could do to allow fragments through without code changes – they’re fundamentally not supported in the NAT

One thing to note is the mentioning of fragmentation according to Microsoft.
Granted the information is about TCP/IP but MTU obviously affects UDP traffic as well.
Azure and VM MTU
The default MTU for Azure VMs is 1,500 bytes. The Azure Virtual Network stack >will attempt to fragment a packet at 1,400 bytes.
Note that the Virtual Network stack isn't inherently inefficient because it >fragments packets at 1,400 bytes even though VMs have an MTU of 1,500. A >large percentage of network packets are much smaller than 1,400 or 1,500 >bytes.
Source https://learn.microsoft.com/en-us/azure/virtual-network/virtual-network-tcpip-performance-tuning

Remove multicast group associated to an interface

with a c# application using the function : clientUDP.joinMulticastGroup(MulticastGroup) i can add a multicast address to a specific interface. The problem is: each time i run my application i add a multicast group to the a network interface, but when the app end it remain joined, so if i run again the app switching the interface it doen't work, than i need to change multicast address and again ...again... in this way i associate a lot of multicast address to each interface.
If i run:
netsh interface ip show joins
it shows my interface with multicast joined
Interfaccia 7: Wi-Fi
Ambito Referement Ultimo Address
---------- ----------- ------ ---------------------------------
0 0 SÌ 224.0.0.1
0 0 SÌ 224.0.0.3
0 0 SÌ 224.0.0.121
0 2 SÌ 224.0.0.251
0 1 SÌ 224.0.0.252
0 0 SÌ 224.0.0.253
0 0 SÌ 224.168.100.2
0 2 SÌ 224.237.248.235
0 0 SÌ 224.237.248.237
0 0 SÌ 239.255.255.3
0 3 SÌ 239.255.255.250
The question is: HOW CAN I REMOVE THIS MULTICAST JOINED FROM EACH INTERFACE ?
There is a shell command only or something i can do on c# too?

My Code (it works only first time i launch my app, than if i run a second time i need to change the multicast address):
private static readonly IPAddress GroupAddress =IPAddress.Parse("224.237.248.235");
private const int GroupPort = 64555;
private static IPEndPoint groupEP = new IPEndPoint(GroupAddress, GroupPort);
//server udp
private static UdpClient serverUDP = new UdpClient(GroupPort);
//client udp
private static UdpClient clientUDP = new UdpClient();
private static IPEndPoint remoteEpClient = null;
manage
clientUDP.JoinMulticastGroup(GroupAddress, IPAddress.Parse(LANSharingApp.umu.GetLocalIP()));
remoteEpClient = new IPEndPoint(GroupAddress, GroupPort);
serverUDP.JoinMulticastGroup(GroupAddress);
for send
clientUDP.Send(ASCIIEncoding.ASCII.GetBytes(message), ASCIIEncoding.ASCII.GetBytes(message).Length, remoteEpClient);
for receive
bytes = serverUDP.Receive(ref groupEP);

Port "COM X" does not exist - is something related to C# program or Machine limitation?

I am a linux programmer venturing into the world of C# programming using windows. I have got a virtual machine( Oracle Virtual box) which runs windows 7. I have checked the ports and it says - COM 1, COM2, etc.However, It seems like my machine doesn't recognise COM1
Here are the errors I get.
What I want to know here is that is it something with my program liking missing some extra API or is it related to my machine capability?
System.IO.IOException: The port 'COM1' does not exist.
at System.IO.Ports.InternalResources.WinIOError(Int32 errorCode, String str)
at System.IO.Ports.SerialStream..ctor(String portName, Int32 baudRate, Parity
parity, Int32 dataBits, StopBits stopBits, Int32 readTimeout, Int32 writeTimeou
t, Handshake handshake, Boolean dtrEnable, Boolean rtsEnable, Boolean discardNul
l, Byte parityReplace)
at System.IO.Ports.SerialPort.Open()
at EFTPOS_SHIM_APP.SerialPortMessenger.SerialPortMessengerStart() in C:\Users
\shreyas\Dropbox\POS_SHIM_EFTPOS_APP\EFTPOS_SHIM_APP\EFTPOS_SHIM_APP\SerialPortM
essenger.cs:line 31
Here is the code -
class SerialPortMessenger
{
private SerialPort port;
public void SerialPortMessengerStart()
{
Console.WriteLine(System.IO.Ports.SerialPort.GetPortNames());
port = new SerialPort("COM1", 9600, Parity.None, 8, StopBits.One);
// attach a method to be called when there is data coming on to the port's buffer
port.DataReceived += new SerialDataReceivedEventHandler(portDataReceivedHandler);
// Begin Communication
try
{
port.Open();
}
catch(Exception ex)
{
Console.WriteLine(ex.ToString());
}
Application.Run();
}
private void portDataReceivedHandler(object sender, SerialDataReceivedEventArgs e)
{
Console.WriteLine(port.ReadExisting());
}
}

Is it possible that your machine does not have a "COM1"? You can use the following code from https://msdn.microsoft.com/en-us/library/system.io.ports.serialport.getportnames(v=vs.110).aspx to check available COM ports:
using System;
using System.IO.Ports;
namespace SerialPortExample
{
class SerialPortExample
{
public static void Main()
{
// Get a list of serial port names.
string[] ports = SerialPort.GetPortNames();
Console.WriteLine("The following serial ports were found:");
// Display each port name to the console.
foreach(string port in ports)
{
Console.WriteLine(port);
}
Console.ReadLine();
}
}
}
Alternatively you can just inspect your computer's Device Manager under "Ports (COM & LPT)" to see available ports on your machine.
You can edit the following line:
port = new SerialPort("COM1", 9600, Parity.None, 8, StopBits.One);
and change the "COM1", to whatever your comport number is. In the long run it would be best to store the COMx value in a settings file, since it will change from machine to machine.
Edit:
You mentioned that you are running on a virtual machine. Have you correctly added COM ports to the virtual machine? See this article: https://forums.virtualbox.org/viewtopic.php?f=7&t=26860 on "How to: Add a Serial Port in Windows XP and 7 Guest."

Com ports get stuck or stop sending serial communication after working for 7-8 hours

I am working on a project for sending hex data continuously to serial com ports from my computer and then from com ports to LEDs (RGB lights) through RS232 USB cable. Sometimes it works for 10 -15 hours and alternate days it gets stopped sending data to ports.
I am using DMX 512 controller, RS232 USB cable with FTDI driver and c# language for coding to send data with SerialPort class.
Here is my code:
public static GO ()
{
try
{
dmx = new Dmx(2, 0);
Thread mTh1 = new Thread(() => dmx.Start(RGBdata1, RGBdata2, RGBdata3));
Global.tmrStarted = true; // test it,ok
mTh1.Start();
}
}
This is my start method where I send data to 3 ports
while (Global.tmrStarted)
{
Break();
Thread.Sleep(500);
if (m_port == null || m_port.IsOpen == false) return;
m_port.Write(new byte[] { 0 }, 0, 1);
SendData();
Break1();
if (m_port1 == null || m_port1.IsOpen == false) return;
m_port1.Write(new byte[] { 0 }, 0, 1);
SendData1();
Break2();
if (m_port4 == null || m_port4.IsOpen == false) return;
m_port4.Write(new byte[] { 0 }, 0, 1);
SendData2();
Thread.Sleep(100);
}
When it gets stopped i try to send data through click on start button but data doesn't gets sent through those com ports till i don't remove my USB cable and plug in again which works after that.
Can anyone suggest me what's real problem with communication ports.Did they get disable by sending continuously data to them .Thanks in advance

I had this problem also,
After all my research, I was find that it happen only in USB to serial COM, because power saving of windows shut them off.
See how configure it in the attached picture.