求助：温湿度传感器的困惑...

求助：温湿度传感器的困惑在做一个工厂温控项目，用到S牌的温湿度变送器QFA65测量室内温湿度，信号电缆为4×0.5mm2屏蔽质优品牌，测量距离约150m，电缆与其他工业电缆同行。在150mm外测量温度信号为6.22VDC（对应温度31.1℃,明显超大），湿度信号3.3VDC（对应湿度33%，晕了！）；在现场断开外接线后测量温度信号5.58VDC（对应温度27.9℃）, 湿度信号4.2VDC（对应湿度42%）；但实际温度为27.6℃,湿度70%;最后改为输出为电流信号的温湿度变送器，测量温度为27.8℃,湿度71.5%,准！我晕了！！

[此贴子已经被作者于2007-4-27 10:58:38编辑过]

hktklzq · 发表于 2007-4-27 07:27:00

.;p.

滄海一溧 · 发表于 2007-4-27 08:29:00

电压信号不能远传，电流信号可以的原因吧

牧马人 · 发表于 2007-4-27 09:17:00

学习

gdfshsan · 发表于 2007-4-27 09:34:00

<span lang="EN-US" style="FONT-SIZE: 10.5pt; FONT-FAMILY: "Times New Roman"; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-fareast-font-family: 宋体;"><shapetype id="_x0000_t75" stroked="f" filled="f" path="m@4@5l@4@11@9@11@9@5xe" opreferrelative="t" ospt="75" coordsize="21600,21600"> <stroke joinstyle="miter"></stroke><formulas><f eqn="if lineDrawn pixelLineWidth 0"></f><f eqn="sum @0 1 0"></f><f eqn="sum 0 0 @1"></f><f eqn="prod @2 1 2"></f><f eqn="prod @3 21600 pixelWidth"></f><f eqn="prod @3 21600 pixelHeight"></f><f eqn="sum @0 0 1"></f><f eqn="prod @6 1 2"></f><f eqn="prod @7 21600 pixelWidth"></f><f eqn="sum @8 21600 0"></f><f eqn="prod @7 21600 pixelHeight"></f><f eqn="sum @10 21600 0"></f></formulas><path oconnecttype="rect" gradientshapeok="t" oextrusionok="f"></path><lock aspectratio="t" vext="edit"></lock></shapetype>以下是S对线径和线长的描述，我的线径为0.5mm2,屏蔽线长150m，有这么大的偏差吗？Connecting terminals for 2 x <chmetcnv wst="on" tcsc="0" numbertype="1" negative="False" hasspace="True" sourcevalue="1.5" unitname="mm">1.5 mm</chmetcnv>2 or 1 x <chmetcnv wst="on" tcsc="0" numbertype="1" negative="False" hasspace="True" sourcevalue="2.5" unitname="mm">2.5 mm</chmetcnv>2Perm. line lengthsCopper cable <chmetcnv wst="on" tcsc="0" numbertype="1" negative="False" hasspace="True" sourcevalue="0.6" unitname="mm">0.6 mm</chmetcnv> dia. <chmetcnv wst="on" tcsc="0" numbertype="1" negative="False" hasspace="True" sourcevalue="50" unitname="m">50 m</chmetcnv>Copper cable <chmetcnv wst="on" tcsc="0" numbertype="1" negative="False" hasspace="True" sourcevalue="1" unitname="mm">1 mm</chmetcnv>2 <chmetcnv wst="on" tcsc="0" numbertype="1" negative="False" hasspace="True" sourcevalue="150" unitname="m">150 m</chmetcnv>Copper cable <chmetcnv wst="on" tcsc="0" numbertype="1" negative="False" hasspace="True" sourcevalue="1.5" unitname="mm">1.5 mm</chmetcnv>2 <chmetcnv wst="on" tcsc="0" numbertype="1" negative="False" hasspace="True" sourcevalue="300" unitname="m">300 m</chmetcnv>If the required line length exceeds <chmetcnv wst="on" tcsc="0" numbertype="1" negative="False" hasspace="True" sourcevalue="300" unitname="m">300 m</chmetcnv>, it needs to be shielded.