模块的外部表现就是它的工作状态的种种显示、种种接口及设定或控制开关。一般讲，模块总要有相应的状态指示灯，如电源显示、运行显示、故障显示等。箱体式PLC的主箱体也有这些显示。它的总线接口，用于接I/O模板或底板，有内存接口，用于安装内存，有外设口，用于接外部设备，有的还有通讯口，用于进行通讯。模块上还有许多设定开关，用以对PLC作设定，如设定起始工作方式、内存区等。
二、I/O模块：
PLC的对外功能，主要是通过各种I/O接口模块与外界联系的，按I/O点数确定模块规格及数量，I/O模块可多可少，但其大数受所能管理的基本配置的能力，即受大的底板或机架槽数限制。I/O模块集成了PLC的I/O电路，其输入暂存器反映输入信号状态，输出点反映输出锁存器状态。
三、电源模块：
ABB Contactor EHW250C2P-1L EHW250C2P1L New
ABB Size 5 Welding Isolation Contactor EHW-250WC-1L
ABB 25A 3pole Circuit Breaker NICE SHAPE CLEAN
ABB CIRCUIT BREAKER S271-K25A MINI CIRCUIT BREAKER
FITS ABB REVERSING CONTACTOR 120V COIL REV-EH145-120V
NIB ABB KB30-2/BRC30-2 240V COIL B25/B30 CONTACTOR N753
ABB CBK-KLTPT1R RED PILOT LIGHT 120V/6V NEW
ABB Circuit Breaker S222-K10A
ABB MODEL 0ETL200K3-2 LOAD BREAK SWITCH 200A NEW
ABB CBK-MPIR1WF1 PUSHBUTTON WHITE ILLUMINATED 120V NEW
ABB S272 K6A 277/480VAC 2 POLE CIRCUIT BREAKER
ABB 57088443 MEM 86-192K + 192K RAM Memory DCG 3200-MR2
ABB AL9Z-30-10-15 Contactor, 24V-DC coil.
ABB MODEL CEL5-10 SIDE MNTG AUXILIARY CONTACT 1 NO NEW
ABB Circuit Breaker S271-K6A ~240/415V
ABB S271K10A 10A Circuit Breaker
NEW ABB FANUC MOD 300 BUS MODULE 6203FP10800 GENIUS
ABB CBK-LTPT1G PILOT LIGHT GREEN 120V/6V NEW
ABB Circuit Breaker S271-K6A
ABB 1200A MOLDED CASE SWITCH
NIB ABB TA42 DU-25 ADJ THERMAL HEATER (18-25A) N758B
ABB Circuit Breaker S271-K2A
ABB Type B Contactor B16-30-22 24-28V NIB __B59.1
ABB Switching Power Supply 24V CP-24/0.5
NIB ABB TA25 DU-25 ADJ THERMAL HEATER (18-25A) N742A
ABB S282-K10A CIRCUIT BREAKER
ABB Circuit Breaker S222-K8A
ABB/Kem Flow Meter ZHM 02/1 ST.E.T 73877-08
ABB Circuit Breaker, # S271-K6A, WARRANTY
NEW ABB FANUC MOD300 BUS MODULE 6203FP10900 GENIUS
ABB Circuit Breaker S271-K20A
NEW ABB FANUC TAYMOD 300 32PT MODULE 6241BP10411 GENIUS
FITS ABB REVERSING CONTACTOR 120V COIL REV-EH300-120V
