When several devices need to be accurately sequenced in a machine vision system, the usual solution was to program a PLC to generate the necessary signals. However, a PLC is a significant investment and requires specialist knowledge to program the Relay Ladder Logic. A dedicated timing controller can save significant engineering effort by performing the same high-performance logic via an easy-to-use interface. Configuration is greatly simplified and this dedicated control technology allows sophisticated and innovative imaging sequences to be created with response times far exceeding the performance of standard PLCs.
Automated machine vision production line inspection solutions can require high speed synchronization and sequencing of machine vision components through flexible triggering of lights, lighting controllers, cameras, proximity sensors, switches, encoders and reject gates. Events must occur within a prescribed latency and determinism. The basic requirement for conveyor belt imaging is that the system senses when the product is underneath the camera, the camera exposure is triggered to record an image, the image is processed accordingly and a pass/fail decision made, and any product that fails is removed from the line at a reject gate. For accurate timing of component sensing, camera triggering and reject gates, timing can be based on precise delays or on exact conveyor belt travel using an encoder. Triggers can be based on timed delays, if the movement of the conveyor belt is uniform, or according to the speed of the conveyor via an encoder input.