Process plc cpu modules and work characteristics

(A) analysis of the controlled object and made a detailed analysis of the controlled object to control the process and work characteristics, understand charged with the object of mechanical, electrical, fluid between the controlled object to the proposed control system PLC control requirements, to determine control scheme proposed design task. (B) determine the input / output control apparatus according to the system requirements, the plc sequence of events module  system determines all the required input devices (such as: buttons, position switch, switch, and various sensors) and output devices (such as: contactors, solenoid valves, , signal lights, and other actuators, etc.), in order to determine the relevant PLC input / output device to determine the PLC I / O points (three) Select PLC
 PLC PLC options include the choice of models, the capacity, I / O modules, power supplies, etc. (d) allocate I / O points and peripheral hardware design PLC line 1. Assign I / O points to draw the PLC I / O points and connection diagram or table correspondence between input / output devices, the part 2 can also be designed to draw the line PLC peripheral hardware rest of the system electrical circuit diagram in step 2, including the main circuit and did not enter the PLC control circuits, etc. . By the PLC's I / O connection diagram and PLC peripheral electrical circuit diagram of a system consisting of electrical schematics. Electrical wiring system hardware have been identified so far. (E) Program Design 1. Program design based on the control system requirements, the use of appropriate design approach to designing the PLC program. To control procedures in order to meet the system requirements of the main line, each writing achievement of the control functions of each sub-task or procedure, and gradually improve the system specified function. In  analog output module addition, the program should normally include the following 1) initialization routine. PLC after power on, usually do some initialization operation, to start to make the necessary preparations to avoid system malfunction. The main contents of the initialization process are: the certain data area, the counter is cleared, etc., some of the data required for recovery of the data area, the relay is set for some or reset, so some initial display state.
  2), such as testing, troubleshooting and display program. These procedures are relatively independent, generally when the program is completed and then add the basic design.
  3) Protection and chain procedures. Protection and chain is an indispensable part of the program, must be considered carefully. The control logic it can avoid the confusion caused by the illegal operation.
 2 simulation debugging program
 Process simulation debugging basic idea is to facilitate the simulation of the actual site in the form of state, to create the necessary conditions for an environment to run the program. Depending on the way to generate on-site signal simulation debugging hardware method and two forms of simulation software simulation.
 1) is to use some of the hardware simulation  plc input output modules hardware device (such as a PLC or some other use input device, etc.) the analog signals to generate a field, and these signals are hard-wired connection connected to the input of the PLC system, the timeliness than strong. 2) simulation software is written in another set in the PLC simulation program to simulate the live signal, which is simple, but not easy to ensure timeliness. Simulation debugging, debugging can be segmented approach, and use the programmer's monitoring function.