Henny Penny KFC Velocity Series Service Manual page 106

6 6 . . 1 1 . . 2 2 . . 1 1 . . 1 1 D D i i g g i i R R a a d d i i o o
The Velocity control board communicates directly with the Digi radio module. The
radio modules are manufactured by Digi with firmware customized for Henny Penny,
to support operator requirements.
The radio module speaks the standard ZigBee protocol on the wireless side, and
speaks RS-485 Modbus protocol on the hard-wired side to communicate with the
fryer's control board. The radio module basically asks the control for a status update
about every 5 seconds, and we send a reply message back to the radio module with
the requested information. The radio module then takes care of converting this
information to the ZigBee wireless format and broadcasts it on to the ZigBee wireless
network.
6 6 . . 1 1 . . 2 2 . . 1 1 . . 2 2 Z Z i i g g B B e e e e P P r r o o t t o o c c o o l l
ZigBee is the name of a type of wireless communications technology and protocol,
just as WiFi and BlueTooth are names for other types of wireless network
technologies.
The advantage of a ZigBee network—particularly in a commercial kitchen where large
panels of stainless steel may obstruct other technologies—is that ZigBee can form a
wireless mesh network, where the various radios that have joined the network are
able to forward messages from one device to another. If a piece of equipment is out of
range or is blocked from communicating directly with some other piece of equipment
at the other end of the building, the radio modules in between can receive and forward
messages as needed. That is, if equipment A cannot talk directly to equipment C, but
A can talk to B and B can talk to C, then A will send the message to B, and B will pass
it on to C.
The ZigBee protocol operates in the 2.4 GHz range and is therefore approved for
operation worldwide. The data rate in the 2.4 GHz band is about 250 kilobits a
second, which is acceptable performance for in-store monitoring of equipment status.
6 6 . . 1 1 . . 2 2 . . 2 2 M M e e s s h h N N e e t t w w o o r r k k
A mesh network is a network topology in which each node relays data for the network.
All mesh nodes cooperate in the distribution of data in the network. Mesh networks
can relay messages using either a flooding technique or a routing technique. The
flooding technique releases the data packets on to the network without specific
routing instructions. The routing technique is more sophisticated and requires a table
of addresses, which is used to route the data packets from point to point.
6 6 . . 1 1 . . 2 2 . . 2 2 . . 1 1 P P r r a a c c t t i i c c a a l l A A p p p p l l i i c c a a t t i i o o n n
In a Smart Kitchen application a ZigBee (wireless) signal can travel through ZigBee
(wireless) enabled appliances regardless of which appliance the signal originates
from. Each ZigBee (wireless) enabled appliance becomes a node on the network.
Eventually the signal reaches a local or virtual (over the Internet) server which
contains the Operator's Smart Kitchen software. The upside is the signal from the
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