SLS1508輸入特性模件,數(shù)據(jù)庫SLS1508
指示完全打開或完全關(guān)閉的閥門。閥門半（50%）開度處于零位
位置（差分電壓為零）。解調(diào)器和LVDT二次輸入（異相）和結(jié)果是代表執(zhí)行器位置的直流偏移。這個位置反饋信號從解調(diào)器輸出傳遞至采樣保持電路。
采樣保持電路對解調(diào)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(shù)轉(zhuǎn)換器這部分位置反饋電路轉(zhuǎn)換將模擬反饋信號轉(zhuǎn)換為數(shù)字值。位置反饋從A/D轉(zhuǎn)換器到數(shù)據(jù)緩沖區(qū)，再到微處理器，到輸入/輸出擴展器總線，最后到MFP單元LVDT振蕩器LVDT振蕩器（頻率可選）向LVDT一次側(cè)提供激勵電壓。該勵磁電壓
在LVDT次級上感應(yīng)差動電壓，指示執(zhí)行器位置。該輸出具有可選增益。設(shè)置雙列直插式開關(guān)可調(diào)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.
