René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Stopped working overnight?  Appears rules aren't being applied.","articleBody":"Hello,\r\n\r\nI got python-usbtmc working yesterday, and was having a good time connecting to my Keysight Ocilloscope, running IDN queries, etc.  All from my Raspberry Pi 3B+.  I followed everything in the readme file, except the optional Kernel bit.  But this morning, it's not working!\r\n\r\nThe output from lsusb:\r\n\r\n```\r\npi@raspberrypi:~ $ lsusb\r\nBus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub\r\nBus 001 Device 005: ID 04d9:0007 Holtek Semiconductor, Inc. \r\nBus 001 Device 004: ID 093a:2510 Pixart Imaging, Inc. Optical Mouse\r\nBus 001 Device 023: ID 0957:0588 Agilent Technologies, Inc. \r\nBus 001 Device 002: ID 2109:3431 VIA Labs, Inc. Hub\r\nBus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub\r\n\r\n```\r\n\r\nMy usbtmc.rules file:\r\n\r\n```\r\n# USBTMC instruments\r\n\r\n# Agilent DSO1052B\r\nSUBSYSTEM==\"usb\", ACTION==\"add\", ATTRS{idVendor}==\"0x0957\", ATTRS{idProduct}==\"0x0588\", GROUP=\"usbtmc\", MODE=\"0660\"\r\n```\r\n\r\n\r\nMy Python3 code:\r\n\r\n```\r\n\u003e\u003e\u003e import usbtmc\r\n\u003e\u003e\u003e inst = usbtmc.Instrument(0x0957, 0x0588)\r\n\u003e\u003e\u003e print(inst.ask(\"*IDN\") \r\n```\r\n\r\nHowever, this morning the exact same code is returning:\r\n\r\n`usb.core.USBError: [Errno 13] Access denied (insufficient permissions)`\r\n\r\nThe Pi was left on overnight, too - so nothing should have restarted, etc.  The USB device was disconnected and reconnected in the morning.  I didn't change anything, other than I probably re-started Python.\r\n\r\n\r\nI've gone back through the readme (again, not the optional part) and I'm just not getting anywhere.  When plugged in, the device is added to `/dev/usbtmc0`.  Using `ls -all`, I get:\r\n\r\n```\r\npi@raspberrypi:/dev $ ls -all | grep usbtmc*\r\ncrw-------   1 root root    180, 176 Jun 11 14:13 usbtmc0\r\n```\r\n\r\nWhich doesn't look right to me.  I've done some udevadm debugging to try and highlight an issue, and I'm seeing this line, which looks wrong, as I'd expect the mode to be picked up from my usbtmc.rules file:\r\n\r\n`usbtmc0: Handling device node '/dev/usbtmc0', devnum=c180:176, mode=0600, uid=0, gid=0`\r\n\r\n\r\nDoes anyone have any thoughts?\r\n\r\n\r\n\r\n","author":{"url":"https://github.com/fallingin2infinity","@type":"Person","name":"fallingin2infinity"},"datePublished":"2021-06-11T14:07:10.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":1},"url":"https://github.com/57/python-usbtmc/issues/57"}