A UK company called Intelligent Distributed Controls (IDC) has developed a simple, low-cost system for cutting maintenance costs on large conveyor installations using low-power wireless communications.

The system is aimed at installations where a central PLC controls a line of several conveyors in sequence. With such systems, it is often difficult to run a single conveyor drive motor independently for maintenance purposes, such as tensioning the conveyor belt.

With IDC’s technology, individual conveyors can be run independently via a handheld barcode reader with a built-in keypad and screen. The reader communicates with the conveyor controls via a wireless gateway, using the low-cost, low-power ZigBee wireless networking technology. The gateway connects to PLCs using Modbus TCP/IP, or to PCs via OPC.

Each conveyor drive motor is marked with a barcode which the reader scans to reveal the motor’s details on its LCD display. Maintenance personnel then confirm the details and select a maintenance mode, allowing them to stop and start the conveyor drive independently.

The ZigBee system can be configured to work with variable speed drives and safety applications, using a wireless “heartbeat” update that stops the drive automatically if the wireless network fails. It can also integrate with wireless beacons and pushbuttons for other duties, such as allowing specific operators to receive system alarms.

For example, maintenance personnel can receive alarms generated by the control system to warn of motor overloads or low air pressure, and take immediate action. Similarly a supervisor can receive an alarm or warning of potential delays, such as conveyor jams or chute-full conditions.