系统 RAM 存储区还包括 PLC 内部各类软设备(逻辑线圈、计时器、计数器、数据寄存器和累加器等)的存储区。该存储区又分为具有失电保持的存储区域和无失电保持的存储区域，前者在 PLC 断电时，由内部的锂电池供电，数据不会遗失；后者当 PLC 断电时，数据被清零。
Bodine Electric 34B6FEBL/FV-F3 Gearmotor 24 VDC
Honeywell W7340C1000 X1365108203 M7215A1016 Trane
Sensidyne HCN 7010698-2-100 Gas Detector Amplifier
Krauss Maffei M093610 Control Board
Moeller MFD-CP8-ME MFD CPU MFDCP8ME
Allen Bradley 22A-D1P4N104 0.5HP VFD AC Speed Drive
ONO SOKKI PS-602 Sensor AMP PS602
ONO SOKKI PS-703 Integrator PS703
Cincinnati Milacron 3-533-0188G SCPU Module
Cincinnati Milacron 3-711-252.6G DV2 Card
Cincinnati Milacron 3-531-4162A SOH Module
OHM ELECTRIC PS-201 CONTROLLER PS201
American Meter USM 3″ ANSI 150 Ultrasonic Flow Meter
Schneider Automation AS-B803-008 Input Module ASB803008
Toshiba EX100 PU11A EX10*MPU11A Programmable Controller
Reliance Electric 0-52803-2 FVCC Control Card 0528032
