A zoological park in the northwestern region of the United States was in need of updated controls for its large animal (rhino and elephant) enclosure gates. The current gates were manually operated and very heavy for the keepers to operate. Additionally, the keepers had to know the status of the gates (open or closed) so the location of the animals were known. The requirements were that the gates needed to be remotely operated and safe for both the animals and the keepers.


After assessing the needs of the customer and the area, it was determined that a PLC with 6 HMIs would be needed to control 15 remote digital I/O points. The I/O points were to be operated with a remote radio transmitter and receiver. Solid-state relays were used to control the hydraulic solenoids that were used to move the gates.