Under the Hood

摘要

Industrial controller redundancy improves system availability, but only if it is implemented with the right capabilities. In many cases, conventional wisdom tells us that if one is good then two are better. This concept extends to the design of industrial automation systems. Even though industrial programmable logic controllers (PLCs) are very reliable, they are a single point of failure susceptible to onboard faults, as well as external problems with power or networking. For critical applications, designers must consider how to address this issue, usually by implementing a secondary backup or redundant PLC.