© Microhard Systems Inc. Confidential 52
3.0 Mesh Configuration
Attempts before Re-Routing
Once a route is entered into the routing table, it is assumed that the route exists and can be used for
data transfer. To ensure that the information in the routing table is up to date and accurate, each time a
packet is sent to a destination the register S126 tracks the number of consecutive failed attempts to
send data before route discovery is triggered. Since all unicast data is acknowledged, the unit will know
if the packet was delivered successfully or not.
S126 = 9 - Number of Attempts before starting route discovery (1-255)
Configuration of S126 must consider multiple factors, the first is the number of retransmissions (S113)
set in the system. The value of S126 must be set higher than the total number of retransmissions.
The next consideration is the collision rate of the system. If an occasional collision is expected, this may
result in a number of unsuccessful attempts to deliver data, but it does not mean that the path is not
valid. Setting the value of S126 lower than the initial transmission + retransmissions + collisions or
packet lose due to noise or interference, may result not only in unneeded route discovery, which has a
large amount of overhead, but it could also result in a system that will never retain a route and become
completely unusable.
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