PLC是按集中输入、集中输出，周期性循环扫描的方式进行工作的。它的中心工作过程分输入采样阶段、程序执行阶段、输出刷新阶段。
在输入采样阶段，首先扫描所以输入端子，并将各输入状态存入相对应的输入映像寄存器中，此时输入映像寄存器被刷新，它与外界隔离，其内容保持不变，直到下一个扫描周期的输入采样阶段。
在程序执行阶段，PLC按从左到右、从上到下的步骤顺序执行程序。
在输出刷新阶段中，元件映像寄存器中所有输出继电器的状态一起转存到输出锁存器中，通过一定方式集中输出，*经过输出端子驱动外部负责，在下一个输出刷新阶段开始之前，输出锁存器的状态不会改变。
YASKAWA ELECTRIC 100W AC SERVO MOTOR SGMAH-01AAA21
ALLEN BRADLEY 24-28V 10A DC POWER SUPPLY 1606-XL240EP S
CONTROL CONCEPTS ISLATROL 120VAC 30A 50/60Hz LINE FILTE
SIEMENS SITOP POWER AS-I 30V 7A DC POWER SUPPLY 6EP1354
FARVAL DM34-100 4 LUBE POINT DUALINE VALVE, NNB
CUTLER HAMMER D26MR22A, TYPE M RELAY, 120 VAC, 60 HZ, P
CENTER LINE SERIES 200, BUTTERFLY VALVE, 3" DISC, 200 P
XYCOM OPERATOR INTERFACE 3100C *FOR PARTS OR REPAIR*
ALLEN BRADLEY MicroLogix 16 POINT RELAY OUTPUT MODULE 1
WHEDCO CONTROLLER IMC-3141-2-B 78003892
BEI M25E-X-HSS4096N-XD7-CR-E-C15-S-5 APPROX 1/4" SHAFT
HARTING CONNECTOR WITH 335625B 70FT CABLE,
EATON CUTLER-HAMMER H1033 HEATER COIL, LOT OF 9, NIB
ALLEN BRADLEY 1770-P1, POWER SUPPLY, 120 VAC, 220/240 V
DWYER 4002C 500 PSIG CAPSUHELIC DIFFERENTIAL PRESSURE G
GRESEN MTB-020-DAPC-06S, REDUCING VALVE, 3/8" NPT, NNB
BUCHER HYDRAULICS M-304, HYDRAULIC PUMP, 36/48 V, 3/4"
ALEMITE 7498 NON-METERED OIL CONTROL VALVE, 60-1500 PSI
SKF, 71905CD/94ADGA, HIGH PRECISION BALL BEARINGS, 25MM
REXROTH BOSCH 8901-702-770 C15 5M FILTER/REGULATOR, NIB
GOULD SHAWMUT A4BX600 600 VOLTS 600 AMPS TYPE 150 AMP-T
TIMKEN TORRINGTON STO10DZ, NEEDLE BEARING, W 50, 1.177"
WC BRANHAM, P38SAF, CALIPER DISC BRAKE, 5/32" THICKNESS
SQUARE D 9007C54B2Y1901 LIMIT SWITCH, 5P MALE, NIB
PARKER 08R713AB PRESSURE REGULATOR, 1 1/2" NPT, 250 PSI
DINGS DYNAMICS 2-63010-524-X1F 115/208-230 VOLTS PHASE
MAGNETEK GPD 315 0.75kW VARIABLE FREQUENCY AC DRIVE MUB
AUTOMATIC VALVE, 407B67S3S3-DB7 PNEUMATIC VALVE, 48 VAC
MITSUBISHI ELECTRIC FREQROL 0.2kW VARIABLE FREQUENCY AC
INDRAMAT CONTROL MODULE AS171/007-000
INDRAMAT CONTROL MODULE AS131/006-000
MITSUBISHI ELECTRIC 3-PHASE 111V 1.4A 200W AC SERVO MOT
