There is a wide choice of extra sensors and accessories that can be added to Vantage Pro stations to allow the design of sophisticated environmental monitoring systems. These include:

• Solar radiation and UV sensors;
• Supplementary stations to measure additional parameters including soil moisture and leaf wetness;
• Additional data display units;
• Installation accessories, including:
  • Ancillary wireless units;
  • Fan-assisted radiation shields;
  • Mounting accessories;

Each of these types of accessories is introduced below. Please contact us for advice on how best to include these items in a system configuration.

Solar radiation and UV sensors

All Vantage Pro stations - cabled and wireless - will accept either or both of these two sensors, which are mounted on a small shelf assembly that sits alongside the rain gauge and that needs to be bought as a separate accessory item. Both sensors, together with the mounting shelf, are included pre-assembled in the VP Plus models.

The UV sensor in particular is a relatively expensive item to make and this accounts for the significantly higher cost of the Plus models. Users interested only in the solar radiation sensor - pictured left though the UV sensor looks similar - can buy this as an accessory (plus mounting shelf) for the standard VP stations at lower cost than buying a VP Plus model. (But for users looking to add both solar and UV sensors soon after buying their initial station, remember that the Plus package price offers a substantial cost saving compared to adding both solar and UV sensors separately).

The solar sensor's purpose is to monitor the sunshine level, obviously an important weather parameter in its own right, but especially relevant also to stations for agricultural applications, for example to allow the calculation of evapotranspiration (ET), which the VP console can display directly. The UV sensor's main application is in monitoring of UV intensity.

Note that the solar sensor measures global solar irradiance levels. This is the sun's strength in units of watts/square metre and the best objective measure of the sunshine's power. The VP console has no direct ‘hours of sunshine’ readout, although this can be calculated, to a first approximation, by the Weatherlink software from logged solar radiation data. More sophisticated algorithms for conversion of logged solar data to sunshine hours are under development.

Measuring additional temperature/humidity values, soil moisture and leaf wetness

The extra sensors necessary to measure additional temperatures, humidity, soil moisture and leaf wetness are termed 'supplementary stations' by Davis - a term we find a little confusing though we use it here for consistency with the Davis catalogue. These so called stations are a small range of wireless-only units consisting of a wireless transmitter in a weatherproof shelter plus various attached sensor elements.  But these are not standalone units - a console is also still required to display the data. Typically, each supplementary station is mounted completely independently of the main ISS and relays data back to the standard VP wireless console via its own separate wireless data channel.

There are certain details to bear in mind when considering supplementary stations:

• Supplementary temperature sensors read to a resolution of ±1°F rather than the 0.1°C of the ISS temperature sensor. (This is a result of how the supplementary data streams are handled rather than of poorer intrinsic temperature accuracy);
• Only certain combinations of supplementary stations can be used to report data back to a single VP console. Data from all permitted combinations can be viewed on the VP console - read how;
• Data from supplementary stations can be logged and handled by the standard Weatherlink logger and software, but there are different constraints on the permitted combinations of numbers and types of sensor as compared to the VP console display;

Wireless temperature and temperature/humidity stations

The 6370 Temperature Station (left) and 6380 Temperature/Humidity station (right) have related but distinct applications. The 6380 Temp/Hum station is similar to an ISS unit in monitoring air temperature and humidity and is supplied complete with radiation shield. The 6370 Temperature station measures just temperature, but it has a sealed stainless steel sensor on a 12' (3.6m) cable that can be used to measure air, soil or water temperatures. (NB Accurate measurements of unshaded air temperature would require purchase of a separate radiation shield.)

A maximum total of eight stations can report back to a single VP console. (Remember though that eight would use all available wireless channels and therefore no other station, not even an ISS, could be used in this configuration.) Each 6370 or 6380 station accepts only a single temperature sensor and therefore one station is required for each additional temperature reading that is to be measured. These units run on a single lithium battery only, that is without solar panel assistance. Each battery should last at least one year,

Wireless soil moisture, leaf moisture and temperature stations

These stations offer several variations on a theme, but all are intended for measurements of soil moisture (potentially at different soil depths), and/or of leaf wetness, plus temperature

There are two types of station; one for measuring soil moisture and temperature only (the 6361) and one for measuring soil moisture and leaf wetness as well as temperature (the 6343)

There are three types of sensor which can be fitted to these stations ; soil moisture, leaf wetness (shown right) and temperature. These can be used in various combinations. The temperature sensor is of the same air/soil/water type as the 6370 station above.

The 6343 is shown to the left (mounting pole not included), but the 6361 is identical. The greater power demand of the 6343 and 6361 stations require that a small solar panel is used to supplement the standard lithium battery.

The 6361 soil moisture/temperature station. For soil moisture measurements in particular, the moisture reading varies with temperature at the probe depth. These Davis stations are therefore designed to temperature-correct each moisture reading individually, which is achieved most accurately if a moisture probe is accompanied by a temperature sensor close by and at the same soil depth. The 6361 station is therefore supplied with one moisture and one temperature probe. Up to three additional moisture and temperature probes can be added, for example to assess moisture at different depths at the same location. So for best results, each extra moisture probe should be accompanied by its own temperature probe. Each probe is supplied with 15' (4.6m) attached cable.

The 6343 soil/leaf moisture/temperature station can be configured as a soil moisture only, leaf wetness only or combined soil moisture/leaf wetness station. Essentially the 6343 will accept combinations of up to three soil moisture sensors, two leaf wetness sensors and up to two or three (depending on configuration) temperature sensors, and again passing all its data back over a single wireless channel. Note though that there are no sensors supplied with the 6343 unit; all sensors must be specified separately.

In fact, both 6343 and 6361 stations can be fitted with temperature sensors only and therefore become specialist temperature sensing stations, with the 6361 accommodating up to four such sensors. Although only one 6361 can be linked to a single VP console, it can pass readings from all four sensors to the console across a single wireless channel.

Secondary Displays

Sometimes you may need additional data displays so that for example weather readings can be seen in two different rooms. Of course, if the Weatherlink data logger is installed then the PC display, which doesn't necessarily need to be in the same place as the VP console, can effectively function as a repeater display. (Read more about PC-based repeater displays.) But often a smaller, always-on display will be preferred, for which Davis provide two options: a second VP main console or a Weather Echo unit. Note that both of these are wireless-only options - it is not straightforward to add non-PC secondary displays to cabled VP stations.

Additional main VP console

The standard VP wireless console can be bought as a separate item, so adding this to a standard wireless VP station will provide a second display. The secondary display can receive its data from one of two sources:

• It can listen to the same (eg ISS) transmitter as the primary display and thereby receive the same primary data stream;
• The primary console can be set to retransmit mode, where it will rebroadcast the data it receives but on a different wireless channel. The secondary display will be set to receive the data stream on the rebroadcast channel;

In both cases, all the usual comments for ensuring good wireless reception will apply equally to the secondary console; in other words it will need to be in good wireless range of either the primary transmitter(s) or of rebroadcast signal from the primary console.

Weather Echo units (NOT available for VP2 stations)

The Weather Echo (7602) and Weather Echo Plus (7603) units are small (5" x 2") desktop units that, as their name suggests, echo a subset of readings rebroadcast from the main wireless VP console. The Plus is identical to the standard Echo other than having a backlight to the display and possessing a humidity sensor for the room in which it is located. (The Plus unit is also supplied with a mains adapter because of the extra power consumed by the backlight).

The Echo units are excellent for providing an inexpensive repeater display of key readings at close hand but the small display is less easy to read at a distance.

Installation Accessories

Wireless Repeaters

Wireless repeaters extend the range possible between primary transmitter (eg the ISS unit) and the main VP console, by receiving the wireless data and retransmitting again at full power and thereby acting as a staging post for the signal. Each repeater can extend range by 40-80m in clear line-of-sight conditions and repeaters may be daisy-chained to cover longer distances. One repeater is able to handle signals from multiple transmitters on different channels.

There are two types of repeater: 7625 (pictured left) is the Solar-Powered variant and will operate in a completely isolated location. 7624 is an AC-powered version and lacks the solar panel; this is the cheaper version but is only suitable for use when a mains supply is close at hand.

Wireless anemometer transmitter

The 6330 wireless anemometer transmitter looks similar to the wireless repeater above and is specially designed to accept the input cable from a standard VP anemometer and to broadcast the wind speed and direction data on a separate wireless channel. With this transmitter, the anemometer can be completely separated from the main ISS sensor assembly and anemometer and ISS mounted in quite different locations. (Normally, the anemometer can be mounted separately from the main assembly, but the two must be connected by cable in order for the anemometer readings to be transmitted back to the console by the single ISS transmitter).

Fan-assisted radiation shield

The standard versions of all VP stations are fitted with a passive radiation shield to prevent sunlight falling directly on the temperature sensor and hence giving erroneously high readings. This passive shield works well for the great majority of days in the year but, inevitably, on the hottest/brightest/calmest days the air temperature inside the shield may be up to 1-2°C above the outside air temperature. For users seeking ultimate temperature accuracy, all VP stations can be specified with a fan-assisted radiation shield (FARS) rather than the standard passive type. A fan actively draws a steady flow of air over the temperature sensor and hence reduces any disparity between temperatures inside the shield and outside.

The FARS shield adds significantly to the cost of a VP station and many customers conclude that it is an unnecessary luxury for the few days a year in the UK when it might make a material difference to temperature readings. However, there is a newly-introduced 7745 Daytime FARS kit (see above right) that may be of interest to some users. This is a simplified and therefore cheaper FARS version that runs off solar power only. It obviously runs only during the day time, but this is of course the only time when shield heating effects are likely to be of any concern. The 7745 unit is a user-fitted kit that may be specified with a new station or bought subsequently.

Mounting accessories

Vantage Pro stations are supplied complete with fixings to attach the outside sensors either to any tubular mast of 32-44mm diameter or to any screwable flat surface such as a wooden post. But there may be circumstances where no suitable fixing point is available. Davis offer two accessories to help out here.

One is a sturdy galvanised tripod (7716 - shown left ) carrying a central mast reaching up to 6' in height, which forms an ideal mounting point for the ISS unit and/or for attaching a further extension pole, for example to carry the anemometer.

The second is a Mounting Pole Kit (7717), containing two pieces of galvanised tube which fit together to form a 3' extension pole.