I got a Silicon Labs CP2102 USB to UART Bridge and i need it to transfer data from my GUI to a Nucleos F446RE.
I want to know if there is a way to define the COM port for the Bridge for other computers as well since on my computer it is COM8 and for a diffrent computer it is COM7.
I know that i could change it manually but not anyone got admin rights and if there is any way to do it automatically it would be great.
If you can, avoid a USB-to-UART bridge for exactly the reason you describe: it basically prevents a good user experience.
It is possible to change the COM port number after installation, just not to preselect it. During installation of the virtual COM device, Windows automatically chooses a COM port number that is not already in use. The avoiding conflicts part is important, and reveals why it is impossible to have the hardware choose the number. (Thanks to Ben Voigt for this part.)
You have several options:
The Nucleo F446RE board has a UBS interface. So you can directly connect it to your PC without a USB-to-UART bridge. Of course, the firmware needs to implement a USB device, preferably with a custom protocol and with WinUSB descriptors. That way, no device driver installation is needed and your application can communicate with the board using the WinUSB APIs.
If this is not possible, another alternative is to select the COM port with matching attributes, in particular with the matching vendor and product ID (VID and PID) - see links below. That way, you can at least narrow it down to a device with a Silicon Labs CP2102, which will often be sufficient to uniquely identify the port.
Another option is to use a USB-to-UART bridge that allows to configure a string descriptor. That way, you can uniquely identify the COM port. For a true plug and play experience, you would need to select a bridge chip that either does not need driver installation as it implements the standardized USB CDC ACM protocol (e.g. PL2303GD) or can automatically install the drivers (such as the FTDI chips).
Links:
https://www.codeproject.com/Tips/349002/Select-a-USB-Serial-Device-via-its-VID-PID
https://aticleworld.com/get-com-port-of-usb-serial-device/
Related
I have an usb device (pole display), which i don't have driver for.
I installed generic usb driver and opened the port for sending(I use bulk transfer) data to device.
With usb monitoring software i see my data gets to device, but nothing much happens on device side.
The device commands(ESC/POS) work when transfered over (virtual) com port, but not over usb port.
Shouldn't device process commands the same way regardless connection type (com vs usb)?
How can i figure out what commands work with the device (for example, if i send some text, i want it to show on display)?
Any help is appreciated!
Look at the USB descriptors the device reports in order to determine its class. If it is a custom device and not a standard class then you'll likely not be able to work with it. There is a big difference between old RS-232 COM protocol and USB. USB devices can have multiple configurations and endpoints, each responding to data in different ways. Many classes exist and are pretty standard (CDC-ACM is typically used for virtual serial ports.) However, it's not uncommon for device manufacturers to include OEM specific configurations and endpoints which can be used for their own custom interfaces, firmware loading, etc.
Is there any initialization data transmitted through the COM port when connecting the device? The device surely can treat COM and USB different, but another possible thing that goes wrong is that the device needs to hear some sort of "I'm going to start sending commands"-signal from you first, and that signal may be different between COM and USB.
So what I would recommend is first (if you have not done that yet) see what data is sent to initialize the COM connection, and if that doesn't have an obvious USB counterpart, connect it to a PC where you do have drivers (assuming that is available somewhere and somehow, which is possible if e.g. you ask this due to OS incompatibility) and see how the connection is initialized there.
If the first doesn't work and the second is unavailable to you, then I'm afraid there's little I can do to help you, since it's usually not visible for you what commands the device wants to hear other than by guesswork, documentation, or comparing to similar devices where you do have that data available.
I have developed a USB device that communicates with linux over a simple but proprietary interface and some custom Linux drivers. My goal is to port this to Windows without writing windows drivers. What I would like to do is find an open source or inbuilt class driver for windows that would look like a COM port in Windows. Then I would tailor the embedded software to match what ever protocol and descriptors the virtual COM port expects to see.
The idea would be that I could plug my device in to a Windows machine and a relatively high speed COM port would appear with out me having to develop Windows drivers for it.
I have been looking at the USB CDC (Communications Device Class) documentation and it looks promising, but I don't know which sub interface would be best to use so that it would show up as a COM port.
Has anyone here done any work like this before or could provide some insight?
Specifically:
Are there virtual COM drivers "built in" to windows or would I need a 3rd party driver.
Which CDC sub class should I use for simple RS232 emulation (No need for modem AT commands, etc)
Is there a better option to do what I am trying to do.
Thanks
There is a USB-to-serial driver built in to Windows that will do what you want. It is called usbser.sys:
http://support.microsoft.com/kb/837637
You will have to write an INF file and distribute that to your users, but that will not be too hard because it is only a few kilobytes of text and you can find examples online.
I'm not aware of any great documentation for this driver by Microsoft, so my advice would be to find some other device that uses it, such as Pololu Wixel, and copy what they did.
Here are the device descriptors we used and the special control tranfers we had to implement:
https://github.com/pololu/wixel-sdk/blob/master/libraries/src/usb_cdc_acm/usb_cdc_acm.c
You can see our INF file, wixel_serial.inf, by downloading the software and looking in the drivers folder:
http://www.pololu.com/docs/0J46/3.a
(There are other files in there that are not necessary for you.)
You can also look at the Arduino Uno because they use the same driver.
Whatever you do, please don't use our USB Vendor ID in your product! You need to get your own.
Update: In Windows 10, you don't need an INF file anymore because of the new usbser.inf driver that comes with Windows.
If you are using a UART you can easily interface it to a FTDI USB chip like http://www.ftdichip.com/Products/ICs/FT232R.htm or a Prolific like http://www.prolific.com.tw/eng/products.asp?id=59
For development, prototype and testing I have half dozen of these laying around http://www.pololu.com/catalog/product/391
I connect it directly to the UART pins on AVR and 8051 micros.
Do I need to buy VID/PID USB identifiers when using virtual COM port through usbser.sys driver on Windows or is the device being tied to a unique COM port sufficient?
The only real advantage to having your own VID and PID is that your device is more identifiable as your product, rather than something generic. Also, you can never guarantee you will be on a certain COM port, as something else may have taken that port number, no matter how obscure.
I would say that unless you are really bothered about your device coming up as something generic in device manager (and you have installed the drivers in a set-up program, so you don't get generic device installed messages on first plug-in) it's not worth bothering. The best bet to find your device is send a quick ID string down each port you can open (starting with your 'unique' one) to identify your COM port by the response.
There may even be some driver-signing woes to get involved with if you have your own PID and VID too (dependent on the USB-chipset vendor).
I have a Arduino app that needs to talk to my PC across the USB (Serial) connection. I have this bit of code that I lifted from the Arduino Playground at
http://arduino.cc/playground/Interfacing/CPPWindows#VisualStudio2008
this->serialPort1->PortName = "COM5"; // Replace with your COM port!
this->serialPort1->Open();
this->serialPort1->Write( "7" ); // In the future, you'll expand on this
// to write your custom data to the board
this->serialPort1->Close();
My question is how does one determine what COM port the Arduino USB cable is attached to?
There are several ways you can approach this.
The most obvious is that you simply make your application configurable and tell it which serial port to use. The port name should never change, unless you have other processes on your machine allocating virtual COM ports such as Bluetooth drivers.
A second option is that you can do what the Arduino app does and scan the serial ports on the system looking for the hardware. Since you are using the CLR, System.IO.Ports.SerialPort.GetPortNames() will give you a list of all the serial ports on the system. (You can also get this from the registry.) Then you can enumerate through them and check the status of the pins to see which serial ports have devices attached. You should probably include in your sketch a way to query the Arduino so that you can send it a command and have it give a fixed response. This would allow you to discern your application from other serial devices such as modems.
There is a third option which would involve figuring out where the FTDI driver stores its configuration information in the system/registry and going from there. This is a bit more involved, so I can't give any information on if this approach is even viable.
I'm developing a project that has a number of hardware sensors connecting to the deployment machine through RS232 serial ports.
But ... I'm developing on a machine without an physical RS232 serial ports, but I would like to make fake serial ports that I can connect to and output data from with the aim of faking input from hardware sensors.
Does anyone know of a way to create a fake serial port and control it on Windows XP?
If you are developing for Windows, the com0com project might be, what you are looking for.
It provides pairs of virtual COM ports that are linked via a nullmodem connetion. You can then use your favorite terminal application or whatever you like to send data to one COM port and recieve from the other one.
EDIT:
As Thomas pointed out the project lacks of a signed driver, which is especially problematic on certain Windows version (e.g. Windows 7 x64).
There are a couple of unofficial com0com versions around that do contain a signed driver. One recent verion (3.0.0.0) can be downloaded e.g. from here.
I know this is an old post, but in case someone else happens upon this question, one good option is Virtual Serial Port Emulator (VSPE) from Eterlogic
It provides an API for creating kernel mode virtual comport devices, i.e. connectors, mappers, splitters etc.
However, some of the advertised capabilities were really not capabilities at all.
EDIT
A much better choice, Eltima. This product is fully baked. Good developer tech support. The product did all it claimed to do. Product options include both desktop applications, as well as software development kits with APIs.
Neither of these products are open source, or free. However, as other posts here have pointed out, there are other options. Here is a list of various serial utilities:
com0com (current)
com0com - With Signed Driver (old version)
Yet another place for com0com with Signed Driver (Pete's Blog)
Tactical Software
Termite
COM Port Serial Emulator
Kermit (obsolete, but still downloadable)
HWVSP3
HHD Software (free edition)
I use com0com - With Signed Driver, on windows 7 x64 to emulate COM3 AND COM4 as a pair.
Then i use COM Dataport Emulator to recieve from COM4.
Then i open COM3 with the app im developping (c#) and send data to COM3.
The data sent thru COM3 is received by COM4 and shown by 'COM Dataport Emulator' who can also send back a response (not automated).
So with this 2 great programs i managed to emulate Serial RS-232 comunication.
Hope it helps.
Both programs are free!!!!!
There's always the hardware route. Purchase two USB to serial converters, and connect them via a NULL modem.
Pro tips:
1) Windows may assign new COM ports to the adapters after every device sleep or reboot.
2) The market leaders in chips for USB to serial are Prolific and FTDI. Both companies are battling knockoffs, and may be blocked in future official Windows drivers. The Linux drivers however work fine with the clones.
Another alternative, even though the OP did not ask for it:
There exist usb-to-serial adapters.
Depending on the type of adapter, you may also need a nullmodem cable, too.
They are extremely easy to use under linux, work under windows, too, if you have got working drivers installed.
That way you can work directly with the sensors, and you do not have to try and emulate data.
That way you are maybe even save from building an anemic system.
(Due to your emulated data inputs not covering all cases, leading you to a brittle system.)
Its often better to work with the real stuff.
i used eltima make virtual serial port for my modbus application debug work. it is really very good application at development stage to check serial port program without connecting hardware.