SLS1508輸入特性模件,數據庫SLS1508
指示完全打開(kāi)或完全關(guān)閉的閥門(mén)。閥門(mén)半（50%）開(kāi)度處于零位
位置（差分電壓為零）。解調器和LVDT二次輸入（異相）和結果是代表執行器位置的直流偏移。這個(gè)位置反饋信號從解調器輸出傳遞至采樣保持電路。
采樣保持電路對解調器輸出1000進(jìn)行采樣每秒次。
SLS1508輸入特性模件位置反饋直接從樣本保持輸出到位置誤差電路，完成反饋回路的控制部分。模數轉換器這部分位置反饋電路轉換將模擬反饋信號轉換為數字值。位置反饋從A/D轉換器到數據緩沖區，再到微處理器，到輸入/輸出擴展器總線(xiàn)，最后到MFP單元LVDT振蕩器LVDT振蕩器（頻率可選）向LVDT一次側提供激勵電壓。該勵磁電壓
在LVDT次級上感應差動(dòng)電壓，指示執行器位置。該輸出具有可選增益。設置雙列直插式開(kāi)關(guān)可調整LVDT的工作范圍允許最大輸出電壓范圍的勵磁電壓在LVDT二級上。
minimum differential voltage indicating a fully open or
fully closed valve. A valve half (50 percent) open is at the null
position (differential voltage is zero). The demodulator sums
the LVDT secondary inputs (which are out of phase) and the
result is a DC offset that represents the actuator position. The
position feedback signal passes from the demodulator output
to the sample hold circuit.
The sample hold circuit samples the demodulator output 1,000
times per second. The position feedback travels directly from
the sample hold output to the position error circuit, completing
the control portion of the feedback loop.
ANALOG-TO-DIGITAL CONVERTER
This portion of the position feedback circuitry converts the
analog feedback signal to a digital value. The position feedback
passes from the A/D converter to the data buffers, to the
microprocessor, to the I/O expander bus and finally to the MFP
module.
LVDT OSCILLATOR
The LVDT oscillator (frequency selectable) supplies an excita
tion voltage to the LVDT primary. This excitation voltage
induces a differential voltage on the LVDT secondary that indi
cates actuator position. This output has selectable gains. Set
ting a dipswitch adjusts the operating range of the LVDT
excitation voltage to allow a maximum range of output voltage
on the LVDT secondaries.
