PyUSB:从USB设备读取(2)

Question

不幸的是，我在Windows下通过USB与PyUSB通信时再次遇到一些问题。在我大约2-3年前的问题中，问题是供应商提供了错误的文档和错误的SCPI命令。

现在，我想与Trinamic的步进电机控制器(TMCM-6110(进行通信。供应商提供的IDE一切都很好，但现在我想通过pyusb解决设备问题，从这个pyusb教程开始。

设备找到了，所以我假设：

• libusb已正确安装并找到
• idVendor和idProduct正确

我必须发送的命令是固定的9字节消息。例如："；移动到位置绝对电机0 12800步"；。字节序列是：b'x01x04x01x00x00x00x32x01x39'，然而，Python将其打印为b'x01x04x01x00x00x002x019'，这让我感到困惑，并花了一段时间才发现这是相同的。

根据print(dev)的输出，我假设地址是3。然而，我收到错误消息：

脚本：

import usb.core
import usb.util
dev = usb.core.find(idVendor=0x2a3c, idProduct=0x0100)
if dev is None:
raise ValueError('Device is not found')
# device is found :-)
print(dev)
cmd = b'x01x04x01x00x00x002x019'
# cmd = b'x01x04x01x00x00x00x32x01x39'
dev.write(3,cmd)

输出：

DEVICE ID 2a3c:0100 on Bus 001 Address 006 =================
bLength                :   0x12 (18 bytes)
bDescriptorType        :    0x1 Device
bcdUSB                 :  0x110 USB 1.1
bDeviceClass           :    0x2 Communications Device
bDeviceSubClass        :    0x0
bDeviceProtocol        :    0x0
bMaxPacketSize0        :   0x40 (64 bytes)
idVendor               : 0x2a3c
idProduct              : 0x0100
bcdDevice              : 0x2e01 Device 46.01
iManufacturer          :    0x1 Error Accessing String
iProduct               :    0x2 Error Accessing String
iSerialNumber          :    0x3 Error Accessing String
bNumConfigurations     :    0x1
CONFIGURATION 1: 100 mA ==================================
bLength              :    0x9 (9 bytes)
bDescriptorType      :    0x2 Configuration
wTotalLength         :   0x43 (67 bytes)
bNumInterfaces       :    0x2
bConfigurationValue  :    0x1
iConfiguration       :    0x0
bmAttributes         :   0xc0 Self Powered
bMaxPower            :   0x32 (100 mA)
INTERFACE 0: CDC Communication =========================
bLength            :    0x9 (9 bytes)
bDescriptorType    :    0x4 Interface
bInterfaceNumber   :    0x0
bAlternateSetting  :    0x0
bNumEndpoints      :    0x1
bInterfaceClass    :    0x2 CDC Communication
bInterfaceSubClass :    0x2
bInterfaceProtocol :    0x1
iInterface         :    0x0
ENDPOINT 0x82: Interrupt IN ==========================
bLength          :    0x7 (7 bytes)
bDescriptorType  :    0x5 Endpoint
bEndpointAddress :   0x82 IN
bmAttributes     :    0x3 Interrupt
wMaxPacketSize   :    0x8 (8 bytes)
bInterval        :   0xff
INTERFACE 1: CDC Data ==================================
bLength            :    0x9 (9 bytes)
bDescriptorType    :    0x4 Interface
bInterfaceNumber   :    0x1
bAlternateSetting  :    0x0
bNumEndpoints      :    0x2
bInterfaceClass    :    0xa CDC Data
bInterfaceSubClass :    0x0
bInterfaceProtocol :    0x0
iInterface         :    0x0
ENDPOINT 0x3: Bulk OUT ===============================
bLength          :    0x7 (7 bytes)
bDescriptorType  :    0x5 Endpoint
bEndpointAddress :    0x3 OUT
bmAttributes     :    0x2 Bulk
wMaxPacketSize   :   0x40 (64 bytes)
bInterval        :    0x0
ENDPOINT 0x81: Bulk IN ===============================
bLength          :    0x7 (7 bytes)
bDescriptorType  :    0x5 Endpoint
bEndpointAddress :   0x81 IN
bmAttributes     :    0x2 Bulk
wMaxPacketSize   :   0x40 (64 bytes)
bInterval        :    0x0

错误1:

Traceback (most recent call last):
File "C:TilmanProgramsPython37libsite-packagesusbcore.py", line 223, in get_interface_and_endpoint
return self._ep_info[endpoint_address]
KeyError: 3

错误2:

During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "Trinamic.py", line 13, in <module>
dev.write(3,cmd)
File "C:TestProgramsPython37libsite-packagesusbcore.py", line 940, in write
intf, ep = self._ctx.setup_request(self, endpoint)
File "C:TestProgramsPython37libsite-packagesusbcore.py", line 102, in wrapper
return f(self, *args, **kwargs)
File "C:TestProgramsPython37libsite-packagesusbcore.py", line 215, in setup_request
intf, ep = self.get_interface_and_endpoint(device, endpoint_address)
File "C:TestProgramsPython37libsite-packagesusbcore.py", line 102, in wrapper
return f(self, *args, **kwargs)
File "C:TestProgramsPython37libsite-packagesusbcore.py", line 225, in get_interface_and_endpoint
for intf in self.get_active_configuration(device):
File "C:TestProgramsPython37libsite-packagesusbcore.py", line 102, in wrapper
return f(self, *args, **kwargs)
File "C:TestProgramsPython37libsite-packagesusbcore.py", line 236, in get_active_configuration
self.managed_open()
File "C:TestProgramsPython37libsite-packagesusbcore.py", line 102, in wrapper
return f(self, *args, **kwargs)
File "C:TestProgramsPython37libsite-packagesusbcore.py", line 120, in managed_open
self.handle = self.backend.open_device(self.dev)
File "C:TestProgramsPython37libsite-packagesusbbackendlibusb1.py", line 786, in open_device
return _DeviceHandle(dev)
File "C:TestProgramsPython37libsite-packagesusbbackendlibusb1.py", line 643, in __init__
_check(_lib.libusb_open(self.devid, byref(self.handle)))
File "C:TestProgramsPython37libsite-packagesusbbackendlibusb1.py", line 593, in _check
raise NotImplementedError(_strerror(ret))
NotImplementedError: Operation not supported or unimplemented on this platform

问题：

• 错误1:KeyError: 3是什么意思？3是错误的地址吗？

• 错误2："NotImplementedError: Operation not supported or unimplemented on this platform"是什么意思？如何修复？

• 为了找出这里出了什么问题，还需要检查和尝试什么？

为什么这些通信示例，无论哪个接口(RS232、RS458、USB、LAN…(都不能立即完成并工作？

Answer 1

这是一个USB CDC ACM设备，因此与它交谈的最佳方式是确保它在"；端口(COM&LPT("；列表，然后使用pySerial打开该COM端口。

如果你编写并签署一个INF文件，告诉Windows为你的设备加载不同的驱动程序(即WinUSB(，你可以使用libusb与它对话，但这是一个很大的问题。像这样对端点编号进行硬编码意味着您的代码只适用于此特定设备。