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USB 原理USB主机功能1.检测设备设备连接或移除时,集线器将事件通知主机,主机便枚举连接新设备或移除设备。在枚举的过程中,主机会决定使用哪种总线速率,指定地址,并请求其他信息。2.管理数据流3.错误检查4.电源管理5.与外围设备交换数据USB设备功能1.检测与通信设备必须检测指向总线上设备地址的通信。设备将瘦的数据存储在缓冲区里,并返回状态码或从缓冲区中发送所请求的数据、状态码。2.响应标准请求所有设备必须对一下请求做出反映:查询设备功能与状态、请求设备采取其他动作。不支持的请求以状态码做出响应。3.错误检查4.电源管理5.与主机交换数据USB传输端点(Endpoint):设备的缓冲区,用 阅读全文
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自动化通讯协定程序自动化▪BSAP▪CC-Link▪CIP▪CAN▪CANopen▪ControlNet▪DeviceNet▪DF-1▪DirectNET▪EtherCAT▪Ethernet Global Data (EGD)▪Ethernet Powerlink▪EtherNet/IP▪FINS▪FOUNDATION fieldbus▪GE SRTP▪HART Protocol▪Honeywell SDS▪HostLink▪INTERBUS▪MECHATROLINK▪MelsecNet▪Modbus▪Optomux▪PieP▪Profibus▪PROFINET IO▪SERCOS inter 阅读全文
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Querying an NTP/SNTP Time ServerOver the last week of so I've noticed several questions in the newsgroups about how to synchronize a CE device's time with a time server. Once again, it's not something I'd done, but I knew there were servers out there that provide the time publicly, s 阅读全文
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GUI Programming with Python: QT EditionThe main topic of this book is application development using PyQt, a library extension to the Python programming language — a library that is meant to form the basis for GUI programming. PyQt is free software, but there is also a commercial IDE available, Black 阅读全文