What is PLC redundancy - Solutions - Huaqiang Electronic Network

SMD aluminum electrolytic capacitor

Photocoupler

Plc redundancy can be divided into software redundancy and hardware redundancy.
Hardware redundancy requires hardware models and connection methods, but there are no special requirements for software.
Always one for the master and the other for the slave.
The slave copies all data from the master for backup.
When the system detects the master abnormality, it automatically realizes the input of the slave without gaps.
The software redundancy investment will not be too large, and the software can be used to read and reserve data, and automatically switch when an abnormality is detected.
In some cases, some people are distinguished by cold redundancy, warm redundancy, and thermal redundancy.

With reference to SIEMENS hardware, there are two models that support redundancy: CPU414H and CPU417H.
In contrast, the latter is faster and has more capacity; but the price is much more expensive! String 7

SIEMENS The above PLC supports the redundancy of two PLCs on the same backplane or two PLCs on different backplanes, which are realized by the daughter card with fiber.
After system configuration, debugging, and input, I tried to manually “stop” the running PLC-master, and the system realized no gap switching. The effect is very good.
In industrial systems, redundant or redundant systems are often used in control sections that are critical to human safety or equipment damage after critical, hazardous or cessation (faults).
According to the experience of using the SIEMENS S7-400, the price of a system using redundant controllers is higher than the price of two independent controllers.
Stable performance and smooth switching.