CODEWITHSUNDEEP
c#windowspowershellserial-portusb
Roman Dulak
Roman Dulak

Reputation: 51

Assign fixed COM ports to keyspan adapters on Windows

I have an application that reads and sends data from/to 2/3 machines attached to the PC through keyspan USB to Serial adapter. Sending/receiving works well.

My problem is that on restart of the PC, the COM ports are assigned "at random", often swapped. That makes automatic processing of data impossible.

I tried to manually set the COMm ports in the Device Manager and with Keyspan assist software without success.

Questions:

  1. how to fix COM ports on Windows so after restart they are always same?
  2. How to assign COM ports with java/c#/powershell (get ports setting and save it(once configured), set on next restart from configuration file)?

Thank you in advance for any suggestions. Roman

Upvotes: 1

Views: 383

Answers (3)

Roman Dulak
Roman Dulak

Reputation: 51

thank you very much for your help.

In the mean time I've slightly modified the solution from http://syswow.blogspot.ch/2013/03/change-device-com-port-via-powershell.html

Unfortunately my current keyspan device ID's are not stable (KEYSPAN*USA19HMAP\00_00 and KEYSPAN*USA19HMAP\01_00 and KEYSPAN*USA19HMAP\02_00), as noted before. These ID's can and often change in between restarts (I suppose as Windows is "registering" them).

I have swapped to another vendor and now I get stable ID's / COM's (FTDIBUS\VID_0403+PID_6001+FTH8ZL5AA\0000 and FTDIBUS\VID_0403+PID_6001+FTH919SZA\0000 etc.).

Thank you once again for your help.

Roman

Upvotes: 1

David Grayson
David Grayson

Reputation: 87406

In my experience, COM port names are stable in Windows. I suspect there is something weird about the way your USB-to-Serial adapters were implemented, or something weird about the Windows driver you are using with it.

However, given that the COM port names are not stable for you, I would suggest using libusbp. It's a USB abstraction libary written in C which can enumerate the USB devices on your system and tell you the names of their COM ports. What you would do is:

  1. Get a list of devices using libusbp_list_connected_devices.
  2. For each device, call libusbp_device_get_os_id. This will return a string that is something like USB\\VID_1234&PID_DA01\6&11A23516&18&0000. That string should be stable across reboots, so you would have a list of those strings in a configuration file for your software.
  3. If you see a device whose ID matches what is in your configuration file, then use libusbp_serial_port_create and libusbp_serial_port_get_name to get the COM port name.

The library is in C, but it can compile to a Win32 DLL, and you can use PInvoke (FFI) to call functions in it from C# or Java. The library might have some minor compilation errors if you try to compile it in Visual Studio, since it is mainly used in MinGW/GCC/clang environments. You should be able to fix those errors and/or report them as issues on GitHub.

Upvotes: 0

Baddack
Baddack

Reputation: 2053

It's not possible without special USB drivers from your vendor. I don't know who made the USB drivers for your keyspan USB, but you might send them an email asking if they offer something like this. We use Silabs CP210X drivers for usb drivers for our products and they offer a special one that makes it so the COM ports are assigned and don't change randomly when our devices are plugged in. You might try it and see, but no promises it will work with your USB.

Upvotes: 0

Related Questions