What is the difference between safety PLC and ordinary PLC?

1) The fail-safe PLC is different from the ordinary PLC in the design of the hardware template.
For example, both input and output modules are designed with dual channels, which can compare and verify the collected signals; in addition, more diagnostic functions have been added to the module, which can detect external faults such as short circuit or disconnection. Make a diagnosis. In addition, a safe CPU can ensure that the transmission and processing of signals in the PLC are accurate through a certain verification mechanism, while ordinary CPUs cannot process safe signals.
2) The fail-safe PLC is safety-certified and can be used in both safety systems and ordinary systems; but ordinary PLCs cannot be used in safety systems.
3) The function blocks of the standard safety functions in the safety program are also certified for safety, and the function blocks of the common program are not certified.
4) The communication between safety-type PLCs ensures data safety through the PROFIsafe protocol. The data exchange between ordinary PLCs is through PROFIBUS or PROFINET protocol to ensure data security. However, the PROFIsafe protocol is loaded on the PROFIBUS or PROFINET protocol layer, and more verification mechanisms are added to the data, so the reliability is higher.
In addition, safety templates can be mixed with standard templates in the fail-safe system, and standard PROFIBUS or PROFINET networks can also be used for safe data transmission.