Codes & Standards - Purchase
The synchronization scheme described herein may be fully implemented within each reader, and such readers when attached to the synchronization bus create a peer-to-peer network (all readers are equal ? there is no dedicated master). Additionally, a cluster of readers, which could be in a master/slave configuration, may also be added to the bus using a dedicated, manufacturer specific Synchronization Interface. The Synchronization Interface presents to the synchronization bus electrical characteristics identical to those of a single peer-to-peer reader.
The transceiver conformance standard ISO 24631-2 permits activation on/off timing tolerances of −0/+1 ms and therefore gives reader manufacturers options as to their preferred method for detecting the HDX header; partial or full. However, when synchronizing readers, irrespective of which header detection method is used, it is critical that all readers adhere strictly to the specific timings and timing tolerances as given in the timing diagrams.
Particular attention should also be given to fault diagnostics which becomes more important when a reader network comprises products from different manufacturers. The obvious case is where a reader which is part of a network has become detached e.g. sync cable break, and it considers it's self to be now standalone and thus permitted to operate asynchronously to the detriment of all other readers.