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.
cpu modules is the heart of the PLC system. It executes the control instructions of the control logic program. It also communicates with other devices, which can include I/O Devices, Programming Devices, computers, Networks, and even other plcs and also performs diagnostics tasks.
2015年7月28日星期二
2015年7月24日星期五
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.
2015年7月20日星期一
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.
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.
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