描述
在继电器控制线路中，当电源接通时，线路中各继电器都处于受制约状态，该合的合，该断的断。而在PLC的梯形图中，各“软继电器”都处于周期性循环扫描接通中，从客观上看，每个“软继电器”受条件制约，接通时间是短暂的。也就是说继电器在控制的工作方式是并行的，而PLC的工作方式是串行的。
Allen-Bradley PLC Processor # 1747-L541 Used NR!
Vickers Proportional Valve KFDG4V32C13NZMU1H720~NEW!
Compumotor M-Series Stepper Motor Drive M578311 Rebuilt
Parker Amplifier Card EW25-104D/4 Rebuilt 6 Mo Warranty
Gould Servo Motor 120-0014-001 Used
Yaskawa Servo Motor USAFED08FA10X Used
New Yuken AMD-L25-S-D24-3505 LVDT Amplifier NOS
Vickers 687245 Torque Motor for Servo Valve SM4-20 New
Vickers 891719 Torque Motor for Servo Valve SM4-30 New
Vickers 684952 Torque Motor for Servo Valve SM4-40 New
Vickers 684953 Torque Motor for Servo Valve SM4-40 New
Yaskawa Servo Motor USAFED-20B 22K Used
Indramat Servo Motor MKD025B-144-KP1-KN Used
GE Servo Motor 183-18-0318-0 Used
Modicon Servo Motor S20-168-001 M443-EAN0-0R0E Used
Elau Servo Motor Model SM070-60-020-P1-44-S1-B1 Used
