Frequently asked questions - HMT140

HMT140 User Guide
Document code
M211488EN
Revision
J
Language
English
Product
HMT140
Document type
User guide

Is the connect time too long?

If the connect time to the network is consistently long (over 5 seconds), HMT140 may not be able to connect to the network. If you suspect the connect time to the network is long:

  1. Use the Test Connect Time tool (see Determining connection problems), or,
  2. Use a PC to connect to the network and then measure the time it takes to connect.
  3. If the network consistently takes longer than 5 seconds to connect, you may need to adjust the settings:
    • Set the Connect Window to a longer value (use the Connect Time tool to help determine this value) or,
    • Change a connection component like channel Auto Find or DHCP.
Extending the connect time may decrease battery life.

Why can't I connect to the wireless network?

  1. Verify that the network exists.
  2. Verify signal strength. Use the built-in signal strength meter. Determine if adequate signal strength exists at that location. See Signal strength.
  3. Verify your network settings.
  4. Make sure the router or Access Point accepts connections of 1 Mbps. Some access points may be set up to exclude certain WLAN data rates. You may have to change the WLAN data rate setting in HMT140.
  5. If HMT140 was previously connected at one location, but will not connect at the new location, temporarily move it to the previous location and verify operation. It is also possible that a setting on the network has changed.

I can connect to the network, but cannot obtain a dynamic IP address

  1. Verify your network settings.
  2. Verify that you are connected to the right network.
  3. Use the Ping from PC function in HMT140 Utility software to see if your PC can ping an address on that network (your PC must be connected to that network).
  4. Use the Ping from PC function in HMT140 Utility (if this PC is connected) and see if you can ping HMT140 when it is in Config mode. Go to the Status tab to determine the IP address.
  5. Use a static IP address temporarily and connect to the network to determine if HMT140 transmissions are being received by the host.
  6. Make sure the DHCP Server has not exhausted the number of assignable IP addresses.
  7. Check if the DHCP Server needs to be configured to accept this type of device (it is possible the DHCP Server is taking too long to respond to the request).

I can connect to the network, but host is not receiving UDP packets

  1. Verify your network settings.
  2. Verify that you are connected to the right network.
  3. Verify that the Destination IP address is correct.
  4. If using the broadcast address, verify that the network can support broadcasts. Most routers by default will not route broadcast traffic.
  5. Use the Ping from PC feature if this PC is connected or a PC on the network and ping the host. Also try pinging HMT140 when it is in Config mode.
  6. Check the following:
    • Is the host ready to receive the transmit packets?
    • Is the host configured to listen for the UDP packets?
    • Is the host software running?
    • Is firewall software installed at the host that would prevent the UDP traffic?
    • Is there anything on the network that would restrict packets from being routed (like MAC filtering)?
  7. Perform a destination test (use the Contact Destination Host function from the Tools tab).
  8. If using a hostname for the destination address, make sure the DNS address is correct (whether set as static or obtained through the DHCP server).
  9. Check if the hostname is being resolved in Config mode (go to the HMT140 Utility Status tab and examine the Resolved Destination field).

I can connect to the network and Contact Destination using HMT140 Utility software, but host is not receiving UDP packets in Transmitter mode

  1. Verify your network settings.
  2. Check if the access point using Auto Channel mode is switching between channels. The access point may have switched to a different channel than is set up in HMT140.
  3. Use the Test Connect Time tool in HMT140 Utility to verify how long HMT140 takes to connect to the network.

    If the network consistently takes longer than 5 seconds to connect to the network, you may need to make adjustments to the settings. Set the connect time window to a longer value (use the Test Connect Time tool to help determine this value) or change a connection component like channel Auto Find or DHCP.

    Extending the connect time may decrease battery life. The battery meter cannot be used to verify battery life remaining if connect times are set longer than the default.
  4. Verify the signal strength where HMT140 is located. Also check how HMT140 is mounted and oriented at this location with respect to the access point. For example, HMT140 is mounted at the back of a refrigerator but may work better being mounted near the top of the refrigerator.
  5. Change batteries.

HMT140 Utility cannot find HMT140

  1. Make sure HMT140 Configuration Cable is connected to HMT140.
  2. Disconnect the cable, power HMT140 off, power back on, wait 5 seconds, connect the cable and try again.
  3. If the red LED in HMT140 Configuration Cable flashes when doing an operation, disconnect the cable from HMT140 and connect again.
  4. Disconnect the cable from HMT140 and then disconnect the cable from the PC. Wait 30 seconds. Insert cable back into PC and into HMT140.
  5. Reboot your computer.
  6. Use an externally powered USB Hub. Your computer may not be supplying enough power through the USB port.

HMT140 Utility network compatibility issue: Data is not reaching destination in Transmitter mode

While in Config mode, HMT140 can connect (associate/authenticate) to the network and Contact Destination is successful, but while in Transmitter mode, the data never reaches the destination. The UDP data packet from HMT140 is not forwarded by the router.

Workaround:

  1. Use Dynamic IP and have DCHP Caching turned off. If the IP address is static or the DHCP Caching is enabled, these routers will not forward the UDP data packet of HMT140.
  2. Replace the router (contact Vaisala Technical Support).

Why does the battery meter indicate a lower battery life than expected?

  1. Confirm whether the battery meter was reset when the batteries were last changed. (See Battery usage.)
  2. Set a longer transmit period.
  3. Check HMT140. Was the SERVICE button pressed frequently?
  4. Check alarm history. Were there a large number of alarms initiating more frequent transmission attempts?
  5. Check transmission attempts. Is the setting for number of tries too high?
  6. Check network quality. Is the connect time for HMT140 greater than 5 seconds? Use the Test Connect Time tool in HMT140 Utility software.
  7. Check the signal strength.