Feedback systems are used to alert operators to conditions that equipment has been or is currently experiencing. The conditions indicated are configured specifically to an application. Many common events that would cause an alert are successful or unsuccessful tag read events, successful or unsuccessful tag write events, improper flow of materials, or items being mishandled. Because a limitless number of events could cause an alert, the parameters that define when an alert occurs must be carefully planned and designed.
The most commonly used feedback devices are the following:
Normally, the lights are connected to a Programmable Logic Controller (PLC) or a general-purpose I/O (GPIO) port of an RFID interrogator. Events and conditions can trigger various lights depending on the programming of the device. For instance, a green light usually means a successful read, while a red light indicates error conditions.
Triggering devices are used to detect the presence of an object in an interrogation zone. Every well-designed RFID system should have triggering devices to ensure the longevity of the equipment, the safety of the system, and the best possible environment in which the system can operate. Without these sensors, interrogators are left to poll constantly, which degrades the equipment over time, floods the area surrounding the interrogation zone with high levels of ambient electromagnetic noise, and can potentially create safety issues due to lengthy exposure to RF for anyone working in the immediate proximity of the interrogation zone.