Dwyer DLI - Manual (Page 92)

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one of the copies will be received even when the other is lost due to interference. (Each packet always contains error
detection, to ensure that invalid data is not displayed.)
Custom Transmit Interval
By default, the transmitter module will transmit a data packet with each internally recorded data
point, or if it is not recording, at the reading rate specified for the data logger. This option allows the
user to specify a custom transmit interval that will be used only by the transmitter. Like the data
logger reading rate, this interval is limited to a minimum of 30 seconds and a maximum of 12 hours,
but unlike the reading rate it may be set to any multiple of 10 seconds. Additionally, the device can
be configured to return new data every interval, or to repeatedly send the data from the most recent
internally recorded reading. This option can be useful for the following reasons:
1. Real-time monitoring – Some applications may require relatively quick feedback of trend data to
the user, but only need to be recorded at longer intervals. With this option, for example, an operator
could check the trend of a system every 10 minutes and make necessary adjustments to keep the
system within specifications, but the official logger record of the data only needs to indicate the value
on an hourly basis.
2. Increasing system reliability – In applications where the operating environment is unfriendly to
RF, this option can be used to repeat the same data multiple times to increase the probability of
successful reception. If the logger is recording every 5 minutes, the transmitter can be configured to
send the data from the last reading every 30 seconds, allowing for 10 transmissions per logger
reading. If the Operations Manual for RF Series Data Loggers Dwyer Instruments, Inc. Revised
5/20/08 Page 8 of 31 environment sees a burst of RF interference a few times per minute, it is highly
probable that one or more transmissions will be received properly.
3. Staggering transmissions from multiple devices – If several devices need to record data at the
same time while transmitting the output in real time, this option can be used to ensure that at least
one transmission from each device is sent without interference from the other devices. This is similar
to the randomization option provided above, but is better suited to some applications. See “Using
Multiple Devices” later in this manual. In the screenshot below, this particular wireless data logger is
set to “delay start” at 1:00PM; since the sample interval is 30 seconds, the next data logger should be
started at 1:00:30, and the next logger should be started at 1:01:00, and so on.