Symptoms: Readings from some or all of the outside sensors are missing, but the console display still works in general and inside readings such as temperature. humidity, pressure, time/date etc are all still present. (If both inside and outside readings are missing then see the topic titled Console seems dead or unresponsive.)

On a cabled station, or on a wireless station with just a single wireless transmitter (e.g. just the standard ISS), all of the outside data is missing. On a wireless station with two or more transmitters then all data from one transmitter is missing.

However, if only one sensor reading is missing (and with other sensors attached to the same transmitter reporting normally) then this is of course likely to be a sensor fault rather than a transmitter fault and troubleshooting should continue with the Sensors topic. (If there is only one sensor attached to a given transmitter such as a 6372 Temperature Station then it may not be obvious whether this is a sensor or transmitter fault and both options will need to be investigated.)

Overall, this topic is concerned with troubleshooting apparent transmitter and console faults rather than individual sensor faults, which are dealt with elsewhere.


Cabled stations

It is rare for cabled stations to develop communication problems between SIM board and console, but if a fault does occur it will usually have one of three causes, for which quick checks are as follows:

  • Cable fault: Check the cable and connections between ISS and console for integrity;
  • SIM board locked up: Turn the console off for 5-10 minutes and then reboot. See Rebooting the console for more details;
  • Misconfigured data channels: Check that the console data channel is still correctly configured;

See below for more detailed comments on each of these possibilities:

Cable fault: The ISS-to-console cable, especially if it has been extended, can be vulnerable to damage over time so a through check of cable integrity should be made. Any joints in the cable need inspecting carefully, as also should the RJ11 plugs at either end of the cable in case one of the four conductors is no longer tightly crimped into its plug. If there’s any residual doubt about the cable then it’s always worth testing with a substitute cable, but preferably a genuine Davis extension cable. (The Davis cables are wired straight-through and while a US-style telephone extension cable may look similar, in practice these are usually crossed over and will not work with a cabled VP2 station.)

SIM board locked up: It is possible for the cabled ISS SIM board to become locked up so that it becomes unresponsive and will not transmit data. This typically happens as a result of an electrical surge, eg a nearby lightning strike, but has been known to happen very occasionally for other reasons. This can be tested for by unplugging the console cable, initially for eg 5-10 minutes and then retrying the connection. If this is unsuccessful then try again for a period of an hour or two and if still unsuccessful then for a still longer period, eg overnight or 24 hours. SIM boards have been known to come back to life after quite extended periods of outage and thereafter to continue to operate correctly for extended periods once they have revived after being powered down for a long period.

Cabled AND wireless stations

Misconfigured data channels: Wireless consoles obviously allow different transmitter types to be set for any of the eight wireless channels. It is not impossible for these channel settings to be mis-set or inadvertently changed and so an important check is to confirm that the channels are still set as expected. And in fact cabled VP2 consoles still retain a similar channel-setting functionality. This is despite the fact that a cabled console can only receive the ISS transmitter type and only on channel #1. It is therefore possible for the cabled console to be configured so as to be set to receive some other transmitter type on #1 or for other channels (ie #2 to #8) to be activated. (This could happen by accident if for example an uninformed user has been playing with the console settings.) While this cause of missing outside data is very rare on a cabled console it’s always worth doing the simple check that #1 is set to ON ISS and all other channels (ie #2 to #8) are all set to OFF.

For wireless consoles, these settings obviously need to be checked against the channel IDs of other active transmitters in the station. See the topic Setting and checking data channels for further details.

Wireless station with wireless repeater(s)

If the station has one or more repeaters in use then the first step is to investigate whether a repeater has stopped retransmitting. See the repeaters topic for further advice. Resume troubleshooting here only if you’re sure that the repeater(s) are functioning normally.

Wireless stations – general troubleshooting

New stations:

If the console appears not to be receiving outside data in a brand new installation (and assuming of course that the transmitter battery has been correctly installed and that the console is within wireless range of the transmitter) then one important initial check is that the transmitter channels have been correctly configured. See the topic Setting and checking data channels for further details.

Existing stations

Data loss may be intermittent or constant, but in either case the first step is always to check the transmitter battery. Battery life is typically 18-24 months, but can be longer or shorter depending on circumstances. With a new loss-of-signal problem it’s always worth replacing the battery as an initial check – this will often resolve the problem. See the Station – low battery warnings topic for further information about the battery and how it works. If the battery has already been recently replaced then double-check that it was inserted with the correct polarity. It’s also not unknown for even new batteries to be faulty, although this is rare. Check also that the battery is tightly in place and that the terminal connections have not become dirty or corroded.

On wireless Vue and VP2 stations,with constant loss of data persisting over many hours or days, the fault is likely to be a supoercap fault on the SIM board of the ISS and troubleshooting that has reached this stage should continue with the SIM board faults topic. But before concluding that the SIM board is at fault, it is always worth checking for misconfigured data channels, as described for the cabled console. This is only rarely an issue but is simple to check and so well worth doing. Corrupted channel settings can be caused by mains-borne interference or eg nearby lightning strikes. Another potential cause can be where some unauthorised individual has been playing with console buttons and has managed to change some of the configuration settings.

Intermittent loss of data is often a sign that the transmitter battery is low – usually this will be accompanied by a warning of ‘Low battery on station X’ visible on the console ticker. Typically the loss of signal from a fading battery will occur overnight when there is no compensating power from the solar panel. Intermittent data loss at other times, especially well into daylight hours, may well have other causes, for example:

  • If there could be another Davis wireless transmitter operating in the same area and on the same channel (typically the default channel #1) then mutual interference can occur, one symptom being intermittent loss of data. If this is suspected as a possible cause then it will be worth setting the ISS and console to a different channel to check whether the problem disappears. NB If you have multiple transmitters, especially having just replaced an old one, or have other transmitters that are not yet set up but which have batteries installed or are simply exposed to daylight then do check that these aren’t the cause of the problem if they may be transmitting data on the same channel as the one in use;
  • If the wireless range being used is close to the maximum such that the signal strength is marginal then changes in weather conditions (fog or rain) or e.g. seasonal growth of vegetation in the signal path can cause the signal strength to drop below an acceptable level leading to loss of readings. It’s worth checking the received signal strength (RSSI) under such circumstances. Parking of large vehicles directly in the straight-line signal path can also have a similar effect.
Last modified: Nov 17, 2021


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