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# Redundancy vs Resiliency Star

#### **Situation:**

In my current role, I work on a large automated structure with hundreds of field devices, where any failure in the system—such as a misconfigured safety fortress door interlock—can cause the entire site to shut down, halting hundreds of Symbots. Given the complexity and critical nature of the system, it’s essential that we have redundancy built into our PLCs to ensure continuous operation.

#### **Task:**

I was tasked with ensuring that the structure’s operations could continue even when one of the PLCs was unavailable. Normally, each PLC manages specific zones, but we had to repurpose one of the phase two PLCs to handle operations in zones 1, 2, and 3 due to a missing power supply in the phase two cabinet. This PLC had to cover driveways beyond its typical capacity while maintaining reliability.

#### **Action:**

I configured one of the phase two PLCs to handle the last five driveways across zones 1, 2, and 3, ensuring that despite missing components in the phase two system, the structure could continue running without any interruptions. This required careful planning and testing to ensure that the PLC could manage the additional load, as the phase one PLCs typically only manage up to 60 driveways each, but the structure had 65 driveways built. I also continuously monitored the system to verify that the PLC was functioning smoothly without overloading or causing downtime.

#### **Result:**

By implementing this redundancy, I ensured that operations continued without any interruptions, even with the power supply issue in the phase two PLC cabinet. This not only prevented downtime but also allowed the project to stay on track, benefiting the customer by maintaining full operational capacity. My actions demonstrated the importance of planning for contingencies and ensuring that critical systems are backed up and prepared for potential failures.

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