請教各位:在三菱PLC控制伺服電機時,有時需要原點回歸,但在原點回歸指令ZRN時卻沒有指定運行方向,但是當伺服處于原點的負方向時,它應該正轉回歸原點;當伺服處于原點的正方向時,它應該反轉回歸原點.是否在運行過程中伺服電機能判斷在啟動時的初始位置在原點的正反方向?

請問版主如果是控制步進電機 ，只用一個光電開關回原點怎么做
如圖
v\:* {behavior:url(#default#VML);}o\:* {behavior:url(#default#VML);}w\:* {behavior:url(#default#VML);}.shape {behavior:url(#default#VML);}   Normal  0    7.8 磅  0  2    false  false  false                                          MicrosoftInternetExplorer4   <!-- /* Font Definitions */ @font-face    {font-family:宋體;    panose-1:2 1 6 0 3 1 1 1 1 1;    mso-font-alt:SimSun;    mso-font-charset:134;    mso-generic-font-family:auto;    mso-font-pitch:variable;    mso-font-signature:3 135135232 16 0 262145 0;}@font-face    {font-family:"\@宋體";    panose-1:2 1 6 0 3 1 1 1 1 1;    mso-font-charset:134;    mso-generic-font-family:auto;    mso-font-pitch:variable;    mso-font-signature:3 135135232 16 0 262145 0;} /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal    {mso-style-parent:"";    margin:0cm;    margin-bottom:.0001pt;    text-align:justify;    text-justify:inter-ideograph;    mso-pagination:none;    font-size:10.5pt;    mso-bidi-font-size:12.0pt;    font-family:"Times New Roman";    mso-fareast-font-family:宋體;    mso-font-kerning:1.0pt;} /* Page Definitions */ @page    {mso-page-border-surround-header:no;    mso-page-border-surround-footer:no;}@page Section1    {size:612.0pt 792.0pt;    margin:72.0pt 90.0pt 72.0pt 90.0pt;    mso-header-margin:36.0pt;    mso-footer-margin:36.0pt;    mso-paper-source:0;}div.Section1    {page:Section1;}--> /* Style Definitions */ table.MsoNormalTable    {mso-style-name:普通表格;    mso-tstyle-rowband-size:0;    mso-tstyle-colband-size:0;    mso-style-noshow:yes;    mso-style-parent:"";    mso-padding-alt:0cm 5.4pt 0cm 5.4pt;    mso-para-margin:0cm;    mso-para-margin-bottom:.0001pt;    mso-pagination:widow-orphan;    font-size:10.0pt;    font-family:"Times New Roman";    mso-fareast-font-family:"Times New Roman";    mso-ansi-language:#0400;    mso-fareast-language:#0400;    mso-bidi-language:#0400;}