2014-11-02 1:54 GMT-02:00 Mark McClure <markfmccl...@gmail.com>: > Hello list: > > I have three A&D EJ-3000 scales that I want to simultaneously acquire data > from every 1 minute over 24-hr periods. All scales have a USB interface. > I've started working through the pyusb tutorial, but before I confuse myself > any further, I thought I'd ask if what I want to do is even possible? Tech > support at A&D told me that retrieving weight data from the scales > automatically (i.e. without pushing the print button on the scales) could > not be done with USB because the interface was uni-directional. Instead, > they suggested that I switch to RS-232. Is this true, and if so why? >
Hi, It really depends on how the firmware behaves, from USB POV, you can always poll the device for data each minute. But might be other constraints that I am not aware of. > I printed the configuration of the scale after installing pyusb and starting > the tutorial. > > > CONFIGURATION 1: 20 mA =================================== > bLength : 0x9 (9 bytes) > bDescriptorType : 0x2 Configuration > wTotalLength : 0x2d (45 bytes) > bNumInterfaces : 0x1 > bConfigurationValue : 0x1 > iConfiguration : 0x0 > bmAttributes : 0x80 Bus Powered > bMaxPower : 0xa (20 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 : 0x1 > iInterface : 0x0 > ENDPOINT 0x81: Interrupt IN ========================== > bLength : 0x7 (7 bytes) > bDescriptorType : 0x5 Endpoint > bEndpointAddress : 0x81 IN > bmAttributes : 0x3 Interrupt > wMaxPacketSize : 0x40 (64 bytes) > bInterval : 0x4 > ENDPOINT 0x2: Interrupt OUT ========================== > bLength : 0x7 (7 bytes) > bDescriptorType : 0x5 Endpoint > bEndpointAddress : 0x2 OUT > bmAttributes : 0x3 Interrupt > wMaxPacketSize : 0x40 (64 bytes) > bInterval : 0x4 > > Any guidance would be greatly appreciated. > -- Best Regards, Wander Lairson Costa ------------------------------------------------------------------------------ _______________________________________________ pyusb-users mailing list pyusb-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/pyusb-users
