GDNET: a Specific Approach to Distributed Input/Output Synchronization for Plastic Machinery

This paper introduces a new Ethernet based communication system, called GDNET, that allows isochronous I/O management tailored for high-performance plastic machinery. In the typical application (four slaves) GDNET allows 6000 I/O points to be scanned in 200 mus. GDNET is independent from hardware and software choices regarding the PC-based master (processor, network interface card, switches, RTOS...), avoiding the need of a jitter-free clock source, still keeping remote input output synchronization in the order of microseconds. Experimental results show that delay between an event (threshold crossing of an analog input) and the corresponding logic output is 800 mus with a standard deviation below 3 mus. Effectiveness of the proposed system is proved by more than 1400 installations.