Vaisala HMT140 - Manual (Page 42)

HMT140 Function Modes
34 VAISALA
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). 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.
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.
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.