描述
在用户程序执行阶段，可编程逻辑控制器总是按由上而下的顺序依次地扫描用户程序(梯形图)。在扫描每一条梯形图时，又总是先扫描梯形图左边的由各触点构成的控制线路，并按先左后右、先上后下的顺序对由触点构成的控制线路进行逻辑运算，然后根据逻辑运算的结果，刷新该逻辑线圈在系统RAM存储区中对应位的状态；或者刷新该输出线圈在I/O映象区中对应位的状态；或者确定是否要执行该梯形图所规定的特殊功能指令。
Reliance 0-49005-1 Cardpak Linear Voltage Time 0490051
RELIANCE ELECTRIC 48267-L RESISTOR 48267L 9.420OHM NIB
Expedited shipping available
1 NEW RELIANCE ELECTRIC 0-57401-C 057401C DRIVE DIGITAL
RELIANCE AUTOMATE 45C1A 45C44 MODULE AUTOMATE 15 45C17B
NIB RELIANCE ELECTRIC 613613-700R 613613700R FIBER
OPTIC CABLE
Reliance 30 hp P32C140A Motor (MOT2165)
NIB RELIANCE ELECTRIC 613613-41S 61361341S FIBER OPTIC
CABLE
NIB RELIANCE ELECTRIC 613613-34S 61361334S FIBER OPTIC
CABLE
NIB RELIANCE ELECTRIC 613613-40S 61361340S FIBER OPTIC
CABLE
RELIANCE ELECTRIC SP500 1SF44002 ONYX DRIVE 2HP TESTED
RELIANCE ELECTRIC 1GA687174 (103774-64) AC DRIVE
RELIANCE ELECTRIC 0-54394-10 USPP 05439410
