Re: [pyusb-users] Digital Multimeter Output

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Le 02/09/2016 à 11:33, Joe a écrit :
> Am 02.09.2016 um 11:22 schrieb Xiaofan Chen:
>> On Thu, Sep 1, 2016 at 10:30 PM, Joe <te...@jo...> wrote:
>>> We use two DMMs UNI-T UT61B. They have two interfaces each, a RS232C
>>> Interface and a USB interface.
>>> The RS232C interfaces work well. Without any command before, the DMMs
>>> continuously send 2 .. 3 packages of 14 Bytes per second. We get them with a
>>> little Python 3.52 script, using PySerial. It's ok.
>>>
>>> But the younger of our computers have no RS232C comports, and I don't want
>>> to use virtual comports. So I try to use the USB interfaces of the DMMs with
>>> PyUSB 1.0, but somethin is wrong with this test script (using Win10 Version
>>> 1607, 64 bit):
>> You need to check what kind of USB protocol the USB interface uses.
>> Maybe it is also a USB Serial Port and you can use the PySerial. If it
>> is not a USB serial port and you do not know the communication protocol,
>> then you have to carry out reverse engineering.
>>
>> Google seems to say that sigrok supports it. You can try ask there
>> for the protocol.
>> https://sigrok.org/wiki/UNI-T_UT61B
>>
> Thank you, Xiaofan, I'll look at sigrok.
> In the mean time I tried another attempt:
>
> import usb.util
> import usb.backend.libusb1
>
> def Gosub():
>       failures = 0
>       failuresmaximum = 48
>       dev = usb.core.find (idVendor = 0x1a86, idProduct = 0xe008) #
> Multimeter UT61B
>       if dev == None:
>           print ('Multimeter UT61B not found')
>       else:
>           print ('Multimeter UT61B was found')
>           print ('dev:\n' + str (dev) + '\n')
>           dev.set_configuration ()
>           ep = dev [0] [0,0] [0]
>           if ep == None:
>               print ('ep is None')
>           else:
>               data = None
>               while failures < failuresmaximum:
>                   try:
>                       data = dev.read (ep.bEndpointAddress, ep.wMaxPackeSize)
>                       print ('Success. len (date): ' + len (date))
>                   except:
>                       failures += 1
>               print ('Failures: ' + str (failures))
>               if data == None:
>                   print ('No data read')
>               else:
>                   for ss in data:
>                       print (str (ss))
>
> print ('Starting')
> Gosub ()
> print ('Ready.-')
>
> Output:
>
> Starting
> Multimeter UT61B was found
> dev:
> DEVICE ID 1a86:e008 on Bus 003 Address 003 =================
>    bLength                :   0x12 (18 bytes)
>    bDescriptorType        :    0x1 Device
>    bcdUSB                 :  0x100 USB 1.0
>    bDeviceClass           :    0x0 Specified at interface
>    bDeviceSubClass        :    0x0
>    bDeviceProtocol        :    0x0
>    bMaxPacketSize0        :    0x8 (8 bytes)
>    idVendor               : 0x1a86
>    idProduct              : 0xe008
>    bcdDevice              : 0x1200 Device 18.0
>    iManufacturer          :    0x1 WCH.CN 
>    iProduct               :    0x2 USB to Serial
>    iSerialNumber          :    0x0
>    bNumConfigurations     :    0x1
>     CONFIGURATION 1: 100 mA ==================================
>      bLength              :    0x9 (9 bytes)
>      bDescriptorType      :    0x2 Configuration
>      wTotalLength         :   0x29 (41 bytes)
>      bNumInterfaces       :    0x1
>      bConfigurationValue  :    0x1
>      iConfiguration       :    0x4 Error Accessing String
>      bmAttributes         :   0x80 Bus Powered
>      bMaxPower            :   0x32 (100 mA)
>       INTERFACE 0: Human Interface Device ====================
>        bLength            :    0x9 (9 bytes)
>        bDescriptorType    :    0x4 Interface
>        bInterfaceNumber   :    0x0
>        bAlternateSetting  :    0x0
>        bNumEndpoints      :    0x2
>        bInterfaceClass    :    0x3 Human Interface Device
>        bInterfaceSubClass :    0x0
>        bInterfaceProtocol :    0x0
>        iInterface         :    0x0
>         ENDPOINT 0x82: Interrupt IN ==========================
>          bLength          :    0x7 (7 bytes)
>          bDescriptorType  :    0x5 Endpoint
>          bEndpointAddress :   0x82 IN
>          bmAttributes     :    0x3 Interrupt
>          wMaxPacketSize   :    0x8 (8 bytes)
>          bInterval        :    0x5
>         ENDPOINT 0x2: Interrupt OUT ==========================
>          bLength          :    0x7 (7 bytes)
>          bDescriptorType  :    0x5 Endpoint
>          bEndpointAddress :    0x2 OUT
>          bmAttributes     :    0x3 Interrupt
>          wMaxPacketSize   :    0x8 (8 bytes)
>          bInterval        :    0x5
>
> Failures: 48
> No data read
> Ready.-
>
> Does anybody see the mistake?
Your device is a HID device.
You can't use PyUSB with HID devices under Windows.
For HID devices I use this : https://pypi.python.org/pypi/hid/0.1.1

Nicolas

>
> Thank you - Joe
>
>
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*Nicolas PINAULT
R&D electronics engineer
*** ni...@aa... <mailto:ni...@aa...>

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