描述
某些输入信号不进入PLC系统中有些信号功能简单、涉及面窄，如图6中的手动按钮、过载保护的热继电器触点等，有时就没有必要作为PLC的输入，将它们设计在PLC外围的硬件电路中同样可以满足控制要求。如果外部硬件电路过于复杂，则应考虑仍将有关信号送入可编程序控制器
National Instruments. CB-27. Connector Block.
National Instruments 182869A-03 3 ft. SCSI To Parallel
National Instrument NI PCI-232/485 2CH 184686D-01
1.1 Meter National Instruments IEEE Cable 488
National Instrument PCI MIO 16XE-50 DAQ 183454F-01
National Instruments VXIpc-486 Model 566 182429M-20
National Instruments CARD PCI-6503 185183B-01 New
National Instruments NI-DAQ Data Aquisition Driver CD
National Instruments NI PCI-6528 Digital I/O 24 in/out
NATIONAL INSTRUMENTS GPIB-RS232 / GPIB-SERIAL CONVERTER
