描述
物理层描述传输介质、连接器和信号脉冲标准。中继器或集线器（hub）也是物理层的设备，它与传输的信息帧的具体内容无关。帧是发送到介质上的一组数字脉冲。用以传输信息。帧的大小为64-1518字节。帧包括预同步信号，消息头、数据信息和帧校验序列。中继器或集线器（hub）仅仅放大导线中的电信号，并继续向前传送。
Motortronics K Plus Controller, # KP1-403, WARRANTY
Cincinnati Milacron PC Board 3 531-3749A WARRANTY
STI Light Curtain Controller LCC-FB-AC1-U-W
Allen Bradley AC Servo Motor, N-3412-2-H00AA WARRANTY
Indramat Servo Drive Motor, # MKD025B-144-KPO-KN, NICE
CHATILLON Dynamometer CSD200 w/ Plastic Case WARRANTY
Kearney Trecker Feedback Subsystem 1-20662-01 REV 13
Fanuc Operator Panel w/ Handwheel # A02B-0091-C161
Allen Bradley Comm Module Board 900052-90 03E WARRANTY
Mitsubishi Meldas PC Board # TCUA-01-DWC BY171A318G54
ALLEN BRADLEY 900036 PC Circuit Board, WARRANTY
Okuma OSP3000/2000 CMOS Memory Board II, E4809-045-191
Fanuc PC Board, A02B-0004-0170, DC Servo Drive Board
