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。
National Instruments NI SCXI-1100 32CH Analog Input Mod
* NATIONAL INSTRUMENTS SCXI-1000 MAINFRAME W/MODULE
NATIONAL INSTRUMENTS NI PCI-GPIB IEEE488.2 183617G-01
National Instruments BNC-2095 w/SH96-96 1-Meter Cable
NATIONAL INSTRUMENTS NI PXI-8335 MXI-3 PXI TO VXI BRIDG
NOB NATIONAL INSTRUMENTS IMAQ PCI-1428 W/ SOFTWARE
NATIONAL INSTRUMENTS NI PCI-6534 DATA CARD 64Mb 32 CHAN
NATIONAL INSTRUMENTS NI AT-MIO/AI-16XE-10 MULTIFUNCTION
National Instruments PCI-6503 & 50 Pin Breakout + Cable
National Instruments NI PCI-232/485 2-Channel
National Instruments SCXI-1000 w/ SCXI-1120 & 1320 ++
National Instruments High-Current 96 Ch PCI-6509
National Instruments PCI-485/8; 8-port RS-485 w/Cable
NATIONAL INSTRUMENTS AT-MIO-16DE-10 MULTIFUNCTION DAQ
