Digimesh™ is a protocol derived from Zigbee, implemented on an exclusivity basis by the U.S. company Digi. Skipping technical details, Digimesh main characteristic (that’s the reason of the name) is the ability to implement a "mesh" between the different devices; i.e. a grid composed by points that can be added, cancelled, moved without affecting communications. Virtually (see figure), with Digimesh nodes are identical and can implement true peer-to-peer communication. In Zigbee, on the contrary, a hierarchy exists between the nodes. Therefore it is necessary to implement a network permanently connected to power source.

We have an excellent knowledge both of Zigbee and Digimesh (Digi modules, operation and protocol limits). We are ready to implement, according to Customer specs, industrial devices based on this interesting new technology.

Zigbee or Digimesh?

Several parameters must be taken into account and the choice is different from case to case. Here are few suggestions, based on our experience:

• Digimesh is best choice whenever it is impossible to create a network infrastructure; e.g. when trasmitters are assigned to people that frequently move or when installed in vehicles.
• Zigbee is a standard; therefore it assures the compatibility with any other device using the same protocol. For commercial applications this probably is a real plus.
• Digimesh has no network coordinator. This is both an advantage and a disadvantage: it is very simple to activate the network and all nodes are interchangeable. On the other side, the Zigbee co-ordinator guarantees more robust communications because it automatically selects some operative essential parameters (channel and extended PAN)
• Zigbee supports coded communications assuring an excellent secrecy level. At present this feature is not available in Digimesh; may be it will in the future.