隔离，这是抗干扰的主要措施。PLC的输人、输出接口电路一般采用光电耦合器来传递信号。这种光电隔离措施，使外部电路与内部电路之间避免了电的联系，可有效地抑制外部干扰源对PLC的影响，同时防止外部高电压串人，从而减少故障和误动作。
H# HP/Agilent E6234A VXI 166 MHz 32MB Opt 002 Win NT
SUN MICROSYSTEMS SPARCengine 1E 270-8057-02
Sciex focus control module 024001
Brooke automation 001-9323-01 Rev A23
Shimadzu part 204-02508 use in UV-2100S
ADVANTECH PCM-9577 Rev. B PCM-9577FG
HV# National instruments VXI-MIO-64XE-10
HV# HP E2251A M-MODULE with 04M027-00 & M1010
HV# HP E2251A M-MODULE with Alfautomazione M1010 M1011
CTC 4285 touch screen display
Schlumberger TH DCSS VXI SSC 97946
DATACON S.I.E System industrie electronic BGR.049.025
DATACON S.I.E System industrie electronic BGR.049.037
Siemens 6GK1143-0AA01 with 6ES5376-1AA11
Tencor instruments TF1 analog/interface assy 104078
