Problems with usb ELM327 using QinHeng HL-340 USB-Serial adapter

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willyk2

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Feb 22, 2013
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For those that do not know this device it is an OBDII scanner interface. Its an inexpensive device that plugs into a vehicle under the dash near the steering wheel and allows viewing the cars built in diagnostic codes on a PC. Per below I am having trouble purchasing one with the USB interface that works. I am trying this post here as there were a couple posts about this device back in 2016, but nothing about the current series with the QinHeng serial adapter.

At one time I owned both an rs232 serial ELM327 and a usb unit. I seem to have miss-placed both although I still have a Bluetooth unit that works fine. I tried to replace the usb unit last month. So far I have ordered 4 of these and none appear to work properly. I own and normally use a laptop running a Slackware 14.1 linux distribution. On this lsusb says all the new units I purchased use the QinHeng usb to serial adapter and require the associated HL-340 driver. I suspect all are some sort of clone from China, but none of these work properly. These are supposed to reply to ascii commands with ascii text in reply. I've written my own code to send commands and read replies, but they are supposed to work fine with a serial terminal interface like 'Putty' or the linux 'screen' program however they don't. I purchased 3 from Ebay all give a reply, but its not ascii, typically the high order bit in each reply character is set so a graphics style char is displayed rather than ascii. A FORSan unit from Amazon gave no reply at all. Most of my tests were done in Linux, but to be sure I borrowed an laptop with Windows Vista installed and it behaved the same way. Have also tried a couple of the Windows and Linux Xwin graphical ELM327 programs. None of these recognize the device and won't connect, presumably due to its non-ascii replys to standard OBDII AT commands. Conversely I now have two Bluetooth ELM327 units and once connected in Linux with rfcomm these work fine with my console software or the 'screen' program.

My question is whether anyone has been successful accessing auto data with one of these units and if so how? I suppose it could be a driver issue on my system, but as I said I also tried with several Windows systems and the behavior was the same. Are these all junk or am I doing something dumb? The usb unit I lost had a different usb interface and worked fine using a prolific driver.
 

kanewolf

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For those that do not know this device it is an OBDII scanner interface. Its an inexpensive device that plugs into a vehicle under the dash near the steering wheel and allows viewing the cars built in diagnostic codes on a PC. Per below I am having trouble purchasing one with the USB interface that works. I am trying this post here as there were a couple posts about this device back in 2016, but nothing about the current series with the QinHeng serial adapter.

At one time I owned both an rs232 serial ELM327 and a usb unit. I seem to have miss-placed both although I still have a Bluetooth unit that works fine. I tried to replace the usb unit last month. So far I have ordered 4 of these and none appear to work properly. I own and normally use a laptop running a Slackware 14.1 linux distribution. On this lsusb says all the new units I purchased use the QinHeng usb to serial adapter and require the associated HL-340 driver. I suspect all are some sort of clone from China, but none of these work properly. These are supposed to reply to ascii commands with ascii text in reply. I've written my own code to send commands and read replies, but they are supposed to work fine with a serial terminal interface like 'Putty' or the linux 'screen' program however they don't. I purchased 3 from Ebay all give a reply, but its not ascii, typically the high order bit in each reply character is set so a graphics style char is displayed rather than ascii. A FORSan unit from Amazon gave no reply at all. Most of my tests were done in Linux, but to be sure I borrowed an laptop with Windows Vista installed and it behaved the same way. Have also tried a couple of the Windows and Linux Xwin graphical ELM327 programs. None of these recognize the device and won't connect, presumably due to its non-ascii replys to standard OBDII AT commands. Conversely I now have two Bluetooth ELM327 units and once connected in Linux with rfcomm these work fine with my console software or the 'screen' program.

My question is whether anyone has been successful accessing auto data with one of these units and if so how? I suppose it could be a driver issue on my system, but as I said I also tried with several Windows systems and the behavior was the same. Are these all junk or am I doing something dumb? The usb unit I lost had a different usb interface and worked fine using a prolific driver.
I have one that has bluetooth. I use it with an Android tablet. I didn't want to deal with a cable.
 
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