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From Friday, April 19th (11:00 PM CDT) through Saturday, April 20th (2:00 PM CDT), 2024, ni.com will undergo system upgrades that may result in temporary service interruption.
We appreciate your patience as we improve our online experience.
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6239有一个24V的逻辑电平。既然逻辑高电平为10-30V,TTL电平不可能达到一个被NI 6239认为是高电平的电压值。因此,计数器无法检测到TTL电平信号的边沿。
24V逻辑电平通常被用于工业应用中,你需要为数字脉冲的产生准备一个外部电源。6239数字输出的电路图如下图1所示,这是一个典型的漏输出,一个连接Vcc的上拉电阻被用于提供一个电压源。既然计数器的输出和NI 6239上的P1是同一个端口,你需要像在数字输出中一样使用相同的配置。
图1 . NI 6239数字I/O连接
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