20
ESL User Manual
5.4.1 Associate interval
When an ESL is not connected to any base station it will automatically start looking for nearby
base stations. Since searching for base station consumes a relative large amount of power it
will not continuously search, but only once every couple of seconds. The associate interval
determines the time (in seconds) between two associating attempts of an ESL. The default
associate interval is currently 15 seconds.
Please note that ESLs consume much more power while not being connected to a base
station than when they
ʼ
re connected, so it
ʼ
s strongly recommended to never turn off the base
stations once a network of ESL
ʼ
s is operating. If ESLs are not being used for a long period of
time the associate interval can best be set to a much longer interval like 300 seconds. For an
even longer period of time, removing the batteries might be the best option.
The amount of power that is being consumed by the ESL, when it
ʼ
s not connected to any base
station is also strongly related to the number of RF channels it is configured for. More
information about the configuration of the
ʻ
Scan Channels
ʼ
can be found in section 5.4.5, below.
5.4.2 Poll Info Ratio
The poll info ratio determines how often ESLs will automatically send their current status and
settings to the base stations. By default the ESLs will transmit this information once every 40
polls, so a ratio of 1:39.
The status and information of an ESL is also requested immediately by opening the settings
dialog of an ESL by right clicking on the ESL. This will cause the base station to request the
settings the next time this ESL polls for data.
The poll info ratio is set to a relative high value, because settings and status usually don
ʼ
t vary
a lot and because sending settings and status information uses more bandwidth and
consumes more power than regular polls for data.
5.4.3 Poll Interval
The poll interval specifies the interval (in seconds) for the ESL to poll the base station for data.
This parameter is the most significant configuration of an ESL since it strongly determines the
response time of an ESL (how fast is an image displayed) as well as battery life.
By default the ESLs poll every 15 seconds once they
ʼ
re connected to a base station. This
means that to response time of an ESL can be anywhere in between 0 to 15 seconds (unless
the poll doesn
ʼ
t arrive at the base station due to interference).
The poll interval greatly influences battery life, so lowering it is not recommended. For example,
changing the poll interval from 15 seconds to 5 seconds will roughly double the power
consumption and thereby shorten the battery life by a factor of 2.
An advantage of making the poll interval bigger is the reduction of the used bandwidth per ESL,
