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I'm trying to get the node-hid (https://github.com/node-hid/node-hid) module working on Windows 7. I can open a device and write to it, but no data ever arrives.

I've verified the device is sending data. I've dug through the node-hid code (HID.cc) and tried several things to get it working:

  • Modified the HID::recvAsync function to use an hid_read_timeout in a loop to see if that would return anything.
  • Set both blocking and non-blocking.
  • Changed buffer sizes to exactly fit what the device sends.

On Windows 8, with the hid_read_timeout call change, this all works fine. I'm not sure what may have changed between the two systems, but I plan on using this on windows XP as well, so I can't just call it good.

I'm struggling to come up with more ideas as to how to debug this issue. Has anyone successfully done this before? Is there a better option to use Node.js with an HID device?

Chris
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  • Have you tried something like Snoopy to see if your data is making it to the device? When you did `npm install` did everything build correctly? – Brad Apr 23 '14 at 01:53
  • In answer to Brad, yes, the messages are making it both ways as I've tested it with other code utilizing HIDAPI. Oddly, trying this on a windows 8 computer I have works once I've made the code use the hid_read_timeout call. I'm beginning to wonder if my habit of not restarting my Windows 7 machine is coming to bite me. I'll post when I can get back to that machine with an update. – Chris Apr 23 '14 at 21:49
  • I never restart either... unless working with hardware. I've had weird issues with USB chipsets where things just don't work properly. You might be on to something there. – Brad Apr 23 '14 at 22:02
  • Well, tested on the Windows 7 machine and it still doesn't work. Same code as before. Very bizarre. – Chris Apr 24 '14 at 21:18

1 Answers1

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After some serious debugging, I found that for some reason I have as of yet not been able to determine, the source file, HID.cc for the node module node-hid needed a call to hid_init() within the constructor before the hid_open call. I'm assuming that somehow this is getting hit with multiple threads, making the safety of calling hid_init before hid_open necessary.

I now have this working on both windows 7 and windows 8.

Summary of changes I had to make: Add hid_init before the hid_open call I'm using. Change hid_read to hid_read_timeout in a loop. (Since reads won't return on windows XP when shutting down otherwise.)

Once I've cleaned it up, I'll send the author my changes.

Chris
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  • I have the exact same issue but I am unable to fix it on windows 10 even when I added a call to hid_init() before hid_open(). I compiled it and it still shows me the error "can't open device with path". I am trying to use a "unitech" barcode scanner which shows up as a keyboard. Is there a work around for this or no. – Mani Jul 01 '19 at 23:37