這SCXI-1126(零件號:776572-26)是一個孤立的頻率輸入模塊從SCXI系列經(jīng)過鎳。該模塊上的所有八個通道都有一個頻率電壓轉(zhuǎn)換電路，具有可編程輸入范圍、閾值、遲滯和濾波功能。這些通道有10個可選的輸入頻率范圍，從250 kHz到128 kHz。每個通道還有四個可選的4極低通濾波器，截止頻率范圍為1Hz-1 kHz。輸出電壓被多路復用到DAQ儀器的一個通道上。因此，用戶可以在一次高速掃描操作中掃描并獲得大量頻率和模擬輸入信號。這鎳SCXI-1126適用于隔離頻率發(fā)生傳感器和其他類型的模擬和數(shù)字周期信號源。

這頻率輸入模塊采用最高250 V的數(shù)字和模擬輸入信號工作。這SCXI 1126是完全軟件可編程的，允許用戶配置每個通道的頻率輸入范圍、閾值水平、遲滯水平和輸出濾波。每個通道的輸入級都與其它通道和機箱分開，最大值為250 Vrms。此外，每個通道在通電或斷電時都不會受到輸入過壓的影響，最高可達250 Vrms。隔離式模擬輸入級由一個觸發(fā)電路組成，該電路將輸入波形與用戶編程的閾值和遲滯進行比較。

由于輸出濾波器的帶寬較低，用戶在修改設置后必須等待約三秒鐘，以使通道在用戶進行精確測量之前保持靜止。此外，NI-DAQ自動查詢模塊，以決定模塊輸出何時穩(wěn)定。

The SCXI-1126 (Part Number: 776572-26) is an isolated Frequency Input Module from the SCXI Series by NI. All eight channels on this module have a frequency-to-voltage conversion circuit with programmable input range, threshold, hysteresis, and filtering. The channels have ten selectable input frequency ranges from 250 kHz-128 kHz. Every channel additionally has four selectable, 4-pole lowpass filters with cut-off frequencies from 1Hz-1 kHz. The output voltages are multiplexed onto one channel of a DAQ instrument. Thus, the user can scan and obtain numerous frequency and analog input signals within one high-speed scan operation. The NI SCXI-1126 is suitable for isolating frequency generating sensors, and other types of analog and digital periodic signal sources.

This Frequency Input Module operates with digital and analog input signals to 250 V maximum. The SCXI 1126 is fully software programmable, which allows the user to configure the frequency input range, threshold level, hysteresis level, and output filtering for every channel. The input stage of every channel is separate from the other channels and from the chassis, to 250 Vrms maximum. Every channel is additionally safe from input overvoltages, to 250 Vrms maximum while powered on or off. The isolated analog input stage is comprised of a trigger circuit that compares the input waveform to a user-programmed threshold and hysteresis.

Since there are low bandwidths on the output filters, the user must wait about three seconds after modifying the settings to enable the channels to stay still prior to the user making a precise measurement. Also, NI-DAQ automatically queries the module to decide when the module outputs are settled.