Transmission Of Data; Transmit Attempts; Alarm-Triggered Transmission - Vaisala HMT140 User Manual

HMT140 User Guide
Config Mode
When the HMT140 is powered on, and the HMT140 Configuration Cable is connected to it, the
HMT140 connects to the network for about two seconds and then goes to sleep. When new
activity occurs, the HMT140 will wake again, connect, then go back to sleep after five seconds.
Transmitter Mode
When the HMT140 is powered on and the HMT140 Configuration Cable is not plugged into it,
data is transmitted according to the transmit settings.
In Transmitter mode, the HMT140 spends most of its time in a very low power state (sleep) to
save battery power. When a transmit period is due, it powers up the radio, attempts to link to
the specified wireless network, transmits its data and then goes back to sleep. The HMT140
transmits based on the configured transmit period or when it is entering an alarm state.
4.3.2 Transmission of Data
The HMT140 will go through the following steps in order to connect to a network and deliver
data:
1. Associates with the network.
2. HMT140 authenticated by the network (depends on the type of security).
3. Requests IP from DHCP Server (if set to dynamic IP)
4. HMT140 receives request from Name Server IP address of hostname (if a hostname is
used for the Destination address and DNS Server specified).
5. Sends data.
6. viewLinc returns acknowledgement.
4.3.3 Transmit Attempts
The HMT140 will initiate a Transmit Attempt repeatedly (typically every 30 seconds) until
either an acknowledgement is received from the host, or the number of tries has been
exhausted. It follows this transmission mechanism both when the transmit period arrives and
for alarm attempts.
CAUTION!
it to join. Without a valid network to join, the device will wait for the maximum
allowable period for a response (Transmit Period multiplied by Tries), thereby
rapidly draining its batteries.
4.3.4 Alarm-triggered Transmission
The HMT140 has the ability to initiate a Transmit Attempt based on an alarm, if this
functionality is configured in viewLinc.
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The HMT140 should not be turned on until a network is available for
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