SLS1508输入特性模件,数据库SLS1508
指示完全打开或完全关闭的阀门。阀门半（50%）开度处于零位
位置（差分电压为零）。解调器和LVDT二次输入（异相）和结果是代表执行器位置的直流偏移。这个位置反馈信号从解调器输出传递至采样保持电路。
采样保持电路对解调器输出1000进行采样每秒次。
SLS1508输入特性模件位置反馈直接从样本保持输出到位置误差电路，完成反馈回路的控制部分。模数转换器这部分位置反馈电路转换将模拟反馈信号转换为数字值。位置反馈从A/D转换器到数据缓冲区，再到微处理器，到输入/输出扩展器总线，最后到MFP单元LVDT振荡器LVDT振荡器（频率可选）向LVDT一次侧提供激励电压。该励磁电压
在LVDT次级上感应差动电压，指示执行器位置。该输出具有可选增益。设置双列直插式开关可调整LVDT的工作范围允许最大输出电压范围的励磁电压在LVDT二级上。
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.
