Troubleshooting; Hmt140 Operation Mode; Signal Strength; Indicator Lights - Vaisala HMT140 User Manual

Chapter 6 – Troubleshooting
6. Troubleshooting
Use HMT140 Utility to help troubleshoot issues that may occur while connecting the HMT140
to a wireless network.
6.1 HMT140 Operation Mode
When the Configuration Cable is connected to the HMT140, it enters Config mode. In this
mode, the HMT140 continuously attempts to connect to the wireless network and stays
connected until the Configuration Cable is disconnected or the setup has changed.
The HMT140 is in Transmitter mode when the Configuration Cable is not connected, and the
HMT140 power switch is turned on. When in Transmitter mode, the HMT140 remains in a low
power state, but will turn on, connect, transmit a UDP packet, and then go back to the low
power state when it is ready to transmit.
6.2 Signal Strength
The HMT140 works best with signal strengths above -63 dBm (for 802.11b mode) and -75 dBm
(for 802.11g mode). If the signal strength is less, the HMT140 may work marginally or not at all.
Stronger signal strength improves transmission performance.
Since the signal strength will vary from sample to sample, you should take multiple samples to
determine the signal strength. View signal strength on the Status tab and in the Available
Networks window (click the Find Networks button on the Setup tab).
6.3 Indicator Lights
The red LED on the main board (Center, or below LCD) indicates that a transmit attempt has
just started. The LED on the radio module indicates that radio module is connected to the
network. When in Transmitter mode the LED will flash when a connection is made. When in
Config mode (the programming cable is connected to the HMT140) the LED will remain on
continuously when a connection is established.
6.4 Access Points
Some access points have a mode called Auto Channel mode where it will move between up to
11 channels. If the access point is using this feature the HMT140 may work properly in Config
mode, but could fail or work very marginally in Transmitter mode. If the access point is using
Auto Channel mode, make sure the HMT140 has "Auto Find" for the channel and the right
channels have been selected for "Auto Find" channels.
Some access points will move between three channels (typically 1, 6, and 11). The HMT140
Utility will work with these access points with the Channel Auto Find feature but the channels
that are used must match the channels for which the HMT140 is configured.
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