PlC of cpu module

plc cpu modules is the control center PLC is the core of the PLC from the nerve center of the action, each PLC has at least one CPU. It functions in accordance with the procedures given PLC system receives and stores from the programmer type of user programs and data; check the power supply, memory, I / O and watchdog timer status, and diagnose user program syntax error. When the PLC into operation, the first of its way to scan each site receiving state and data input device, and are stored in the I / O image area, then one by one to read the user program from the user program memory, after the command interpreter Press the results of the implementation of the provisions of the instruction of a logical or arithmetic fed into the I / O image area or a data register. And so after all of the user program is finished, the final transfer of data I / O image area of each output state or output register to the appropriate output device, so the cycle run until it stops running.

What is the definition of PLC, programmable logic controller

Programmable logic controller, said the English Programmable Controller, called PC. However, due to the personal computer PC is easy and (Personal Computer) confused, so people are still accustomed to using plc communication modules as an abbreviation. Electronic digital computing device operating system, it is a microprocessor core, specifically designed for applications in the industrial field, for it uses programmable memory for storage in its internal implementation of logical, sequential control, timer / counting and arithmetic operations such as operating instructions, and digital or analog input through output interface, control of all types of machinery or production processes. PLC is the product of computer technology with traditional relay contactor control technology, which overcomes the wiring relay contactor control system complex mechanical contact, low reliability, high power, versatility and flexibility shortcomings of the poor, full advantage of the microprocessor, and take care of operation and maintenance personnel to the site electrical skills and habits, especially PLC programming does not require specialized knowledge of computer programming languages, but with a set of relay ladder based simple instruction form, so that the image of the user programming, intuitive and easy to learn; debugging and troubleshooting is also very convenient. After the user to purchase the desired PLC, just follow the prompts manual, do a small amount of wiring and easy user programming work, it can flexibly and easily be applied to production practice PLC.

Programmable Logic Controller (PLC) features

Industrial control equipment reliability requirements:
① MTBF long time
② time to repair (MTTR) Short
Any failure electronic devices, usually two:
① sporadic fault. Due to the harsh external environment, such as electromagnetic interference, ultra-high temperature, ultra-low temperature, over voltage, under voltage failure caused by vibration and so on. Such failures, they do not cause damage to system components, once the environmental conditions return to normal, the system also will return to normal. But for PLC, the rear outside influence, the information stored inside may be damaged.
② permanent failure. Since the components can not be restored and the destruction caused by the fault.
If we can limit the occurrence of sporadic fault condition, the consequences will not be affected if the PLC or able to make impact in harsh environments is limited to a minimum, make programmable logic controller (plc) suppliers automatically disappear after the harsh conditions return to normal, so that we can improve MTBF time; if we can increase the number of diagnostic measures and appropriate means of protection in the PLC, when a permanent failure, can quickly find the point of failure and faults locally, can reduce mean time to repair the PLC. To this end, each PLC manufacturer has taken various measures in terms of hardware and software, so that PLC in addition to their strong self-diagnostic capabilities, in time with an error message, stop waiting for repair, but also make the PLC has a very strong anti-jamming capability.

Micro & Nano programmable control system

Our micro and nano-PLC can provide an economical solution to meet the basic needs of a simple mechanical control, including relay replacement, and simple control timing and logic. The controller uses a compact package, integrated plc IO module and communication, and easy to use, ideal for conveyor automation, security systems and building and parking lot lighting applications projects.

PLC basic instruction Overview

FX series Plc logic controllers basic logic instructions 20 or 27, stepping instruction 2, features more than 100 instructions (different series vary).
FX2N plc temperature control module  a total of 27 basic logic instructions, which contains 20 basic logic instructions some sub-series plc input output modules.
Instruction fetch and output instruction (LD / LDI / LDP / LDF / OUT)
(1) LD (instruction fetch) a normally open contact and left instruction bus connection, a normally open contact each logical row starting with this directive.
(2) LDI (negated instruction) a normally closed contact and left the bus connection instruction, a normally closed contact each logical row starting with this directive.
(3) LDP (transition instruction fetch) normally open contact with the left leading edge detection instruction bus connected only at the rising edge of the specified bit device is turned on when a scan cycle (from the OFF → ON).
(4) LDF (falling instruction fetch) normally closed contacts of falling edge detection instruction and left the bus connection.
(5) OUT (output command) coil for driving instruction, also known as output instruction.

Programmable Logic Controller (PLC) of the workload of the design and

construction of the control system
Since the digital output plc using a relay control system software to replace a large number of intermediate relay, time relays, counters and other devices, the control cabinet design and installation of wiring workload greatly reduced. Meanwhile, plc controller manufacturer user program can simulate debugging in laboratory, but also reduce the workload of site commissioning. Also, due to the low failure rate micro smart plc and strong monitoring, modular, etc., so maintenance is also very convenient.

Programmable Logic Controller (PLC) software measures:

We have a strong self-test and protection.
① fault detection - software periodically to detect the external environment, such as a power failure, under voltage, battery voltage is too low and strong interference signals. So that timely treatment.
② Information Protection and Recovery - When sporadic fault condition occurs, does not destroy the plc cpu modules's internal information. Once the fault condition is removed, you can return to normal, continue the original program of work. Therefore, intelligent plc when the fault condition is detected, immediately put the current state stored in the memory, software with the memory is closed to the memory of any action to prevent the storage of information is obliterated.
③ Set the Watchdog WDT (Watchdog) - If the program execution time per cycle than the WDT specified time, indicating the program into an infinite loop, call the police.
④ strengthen inspection and verification procedures - once the program is wrong, call the police, and stops executing.
⑤ the program and dynamic data backup battery - after a power outage, use battery-powered back-up, and information about the status will not be lost.
Plc modules factory pilot project, there is an immunity test. It is required to withstand the amplitude of 1000V, the rise time 1nS, a pulse width of the pulse 1μS of interference. In general, the average time between failures of up to hundreds of thousands - tens of millions of hours; the system can be made up to 4 to 50,000 hours or longer.