I have datalogic qd2131 hand scanner, want to use with java pos
after scanning the interface usb-oem the scanner dies
please help in enabling the scanner
It was a long time ago in a galaxy far far away ....
but disconnect device, hold 5 sec trigger, connect device. Release trigger. Some seconds it will be flashing. Then reconnect device.
Related
The scanner is bluetooth connected to the android device.
Scanner loses connection after some time (approx. 2 days). When trying to reconnect, it connects to the device for a while and loses it again. I tried to update the android system, reset to factory settings.
I've problems with a MODBUS RTU connection to devices after a disconnect & reconnect of the RS232. The system is build up the following way:
MODBUS RTU device with A+ & B- clamps (no C = GND available, e.g. electricity meter SDM120, but problem also appears on other device types)
RS485 wires A & B
Adapter RS232 -> RS485 DA-70161 based on SP485EE chip
RS232 cable with DSUB9 connector
UART connected MAX3243 chip for RS232 with CTS/RTS
libmodbus software using /dev/ttymxc0 configured for 9600baud 8N1 (fitting to device defaults)
Linux kernel 4.4.0 embedded ARM CPU
In general this works fine, even over weeks. But once one disconnects the RS232 cable and reconnects it after some seconds (or minutes or hours), the libmodbus gets timeout-errors on every access to the MODBUS device.
This is very annoying, because it is difficult to get it back to work again. Only a lot of further disconnects of both ends of the RS232-RS485-Adapter will bring it back, after some minutes and up to 10 retries.
Any idea what could cause this problem?
Any help what to do to prevent this and immediately work after reconnect the RS232 cable?
(Yes, one possible solution is to simply let the RS232 cable be always connected. But sometime somebody need to do something and forgot about the consequences - I think this is not a realistic option)
I've got an solution, with help of mikrocontroller.net forum:
Using another RS232 → RS485 adapter DeLock 62919 and powering with +5V on the clamps by dedicated power-supply, did the job!
Now the communication comes up again, even after RS232 was un- and replugged
I'm working on a project where a USB audio card is unplugged and plugged arbitrarily from a computer that will be playing sounds. My software should be playing sound as soon as possible right after the card is plugged in.
In order to detect the USB being connected, I'm using libusb's LIBUSB_HOTPLUG_EVENT_DEVICE_ARRIVED and LIBUSB_HOTPLUG_EVENT_DEVICE_LEFT events, and it works flawlessly. As soon as the device is connected to the USB port, the event is triggered. Same when it's removed.
The problem I'm facing is that there's a time gap between the moment libusb detects the device, and the moment I can actually start working with the device to play sound. I'm using miniaudio to play a sinewave, but the issue is the same using Qt Multimedia, so I'm guessing it has to do with the backend (ALSA).
I've had to place an explicit wait of around 5/6 seconds after the device is detected by libusb to be able to safely open it with miniaudio, but I'd rather not have that magic number right there.
Is there any other way of knowing when the device is ready? I've tried checking udev but it gets activated at the same time as libusb.
I'm trying to get a "Selfie stick" to work on Windows Phone 8.1.
The Selfie stick is a HID device and is used as a keyboard, when the shutter button is pressed on the stick it sends an "Enter" keystroke to the connected device.
So far for the logic, the problem is that when I try to pair it with my phone it only stays connected for about 5-10 seconds and then disconnects.
I'm new to bluetooth coding and I read that some bluetooth profiles are not supported, is this true for HID keyboards as well?
Thanks,
Peter Larsson
As it is a keyboard, simply handle keyboard events such as KeyDown and check if it is Enter. No need to deal with Bluetooth yourself.
It could be a media key (volume up) as well.
Bluetooth keyboard should stay connected. Try upgrading to Windows 10 Mobile (Fall Creators Update) where more Bluetooth APIs are available.
If it keeps disconnecting, there is not much you can do.
I am working on an application (windows phone 8.1), which is the following: if my phone is already connected to a bluetooth device then it should connect in parralel to another device which is already paired("cc2541"). I would appreciate a little help with the coding.
My problem is i don't know how to connect to a device automatically. I only found code samples that are only scans and lists devices and it only connects when I touch the screen ( approve the connectivity ).
You can get the RSSI value (signal strength) for each device, then you can implement a dispatcherTimer, where you start the scanning as the timer starts and then connect to the closest device on a timeout.
This is a basic example of automatic connection establishment.