主要内容
使用NI设备测量频率
此示例显示如何使用流量传感器测量频率以确定流体流速。传感器产生一个数字信号，其频率与流体流速相关。
创建计数器输入通道
使用数据采集创建数据采集和附加输入添加计数器输入通道的步骤频率测量类型。对于本例，请使用CompactDAQ机箱NI c9178和ID为cDAQ1Mod5的模块NI 9402。
dq=daq(“倪”); ch=附加输入（dq，“cDAQ1Mod5”,“ctr0”,“频率”); 中国
ch=索引类型设备通道测量类型范围名称uuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuu
确定计数器输入通道的端子
要将输入信号连接到正确的端子，请检查航空站信道的属性。终端由硬件决定。
ch.航站楼
ans=‘PFI1’
测量频率
要确定计数器是否工作，请在电机旋转时输入一次扫描。
读取（dq）
ans=时间表时间cDAQ1Mod5\u ctr0\uuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuu0秒100
随时间监控频率
使用硬件时钟随时间获取多个计数器测量值。NI计数器设备需要一个外部时钟。通过为同一机箱上的模块添加模拟输入通道，会话将与两个模块共享一个内部时钟。
dq=daq(“倪”); dq.比率=1；附加输入（dq，“cDAQ1Mod1”,“ai0”,“电压”); 附加输入（dq，“cDAQ1Mod5”,“ctr0”,“频率”); 数据=读取（dq，秒（10））；绘图（data.Time，data.cDAQ1Mod5_ctr0）；
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