描述
A值越大越好，它可使PLC系统得到充分的利用，是为什么要使用PLC的重要指标。而从上式可知，MTBF越大，MTTR越小，则A越大。所以，PLC的可靠措施都是围绕提高MTBF及MTTR值进行的。
鉴于可靠工作是PLC的重要特点，至关重要，故有关提高MTBF及降低MTTR的措施如何，以及PLC的MTBF与MTTR值也成为PLC性能的重要指标。
National Instruments NI SCXI-1193 Multiplexer/Matrix
National Instruments MID-7652 DC Motor Servo Drive
National Instruments NI NI USB-8451 Card
National Instruments PXI-1010 8-Slot PXI/4 SCXI Chassis
One-day shipping available
NATIONAL INSTRUMENT SCXI-1001 USPP SCXI1001
National Instruments SCXI-1001 12-Slot Chassis
One-day shipping available
National Instruments DAQ Board PCI-MIO-16E-4 PCI-6040E
National Instruments PXI-7344 Servo/Stepper Motion Cont
One-day shipping available
National Instruments NI PCI-7344 Card
National Instruments NI IMAQ PCI-1409 Card
HV# National instruments VXI-MIO-64XE-10
National Instruments NI PXI-6070E Card TESTED
National Instruments NI PXI-6711 Card TESTED
