© Microhard Systems Inc. Confidential 50
3.0 Mesh Configuration
Sync Timeout
Once synchronized to the network the unit does not need to receive sync data often to keep track of
where the system is supposed to be (in time and frequency). The sync Timeout defines the number of
frames where no sync data is received from a coordinator before losing sync. In other words, how long a
unit will remain synchronized with the network without receiving any sync packets before it gives up and
loses sync.
S248 = 100 Sync Timeout (4-65534)
Setting a value too low will cause the unit to lose sync easily and time will be wasted trying to re-sync to
the network. As seen with the Mesh Duty Cycle several frames can go by without receiving a sync
packet, and this is completely normal. If this value is set too high, the unit will assume for a long time
that the network is still out there, when especially in mobile applications, it may not be.
Quick Sync
In a quiet Mesh network it may take some time to synchronize the entire network. To overcome this
problem, Quick Sync is used by coordinators when they first come online to quickly send a number of
sync packets on random frequencies in the current hop table. This allows the network to synchronize
much faster than waiting for the standard sync packets to arrive (which is based on the sync duty cycle
and number of sync slots). The number of sync packets sent upon power up is defined by the S151 reg-
ister.
S151 = 500 Quick Sync Packets (5-65534)
When a Primary Coordinator goes online it will send the configured number of sync packets. Once a
Secondary Coordinator is synchronized, it will also transmit quick sync packets based on their config-
ured S151 value.
No data transmission can occur while the coordinators are sending quick sync packets, even if all units
are synchronized.
When setting the S151 register, selecting a large value may create an unnecessary delay in data trans-
mission on system startup. A value too low, or not sending enough sync packets to cover all the fre-
quencies in the Hop Pattern will result in slower synchronization of the system as any units that did not
hear the quick sync packets will need to wait until they receive a standard sync packet to synchronize.
North America FCC requires that different 50 frequencies(channels) are used to create the hop pattern.
The default value of 500 means that 10 packets are sent on each channel to ensure system wide syn-
chronization. Customers located in other regions or government organizations who allow or require
more or less entries in the hop pattern may decide that the default value is not appropriate for their sys-
tems, and are free to adjust this value.
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