Sensor installation and maintenance

Read this guide before you install or use the unit. It is based on the CropWatch Sensor Series User Guide (CW-UG-001, Rev A).

You can carry out the maintenance described here yourself: replacing the battery, the sensor module, the base magnets and the sensor mesh filter. For any other repair, disassembly or part replacement, contact CropWatch.

Every model in the Sensor Series uses the same enclosure.

• Base: holds the battery holder and the main board.
• Sensor chamber: the sensor module sits in its own chamber at the vent end, behind the vent slots.
• Top cover: held on by eight screws. The radio antenna is inside it.

You can mount the unit with its magnets, with a bracket, or stand it on a table. Whichever you choose, these rules apply:

• Keep plenty of clear space around the top cover. The antenna is inside it. Metal, concrete and anything holding a lot of water block or absorb radio waves and shorten the range.
• On a wall or pole, point the sensor vent down. Dust and water droplets then cannot collect in it.
• Keep it away from vibration and knocks. Not on machinery or near fans that shake continuously, not above doors, and not where people or objects can bump into it.
• On a wall or pole, keep the unit upright, at a height that represents the space you are monitoring.

The four magnets on the base hold the unit to any magnetic surface: racks, machine frames, steel columns, cold-room panels, door frames.

1. Choose a flat, clean surface that does not vibrate.
2. Wipe off dust, rust, water or ice.
3. Put the unit in place and check it does not wobble.

Where magnets cannot be used, use a bracket or strap. Afterwards, check that the unit is held securely and cannot slip or fall.

Do not mount it where it cannot be held firmly, such as on slippery or wet surfaces or on tapered poles. A loose strap or a slippery pole lets the unit slide out of place or fall.

On a desk, shelf or other flat surface, make sure that:

• No water or condensation collects on the surface. Avoid spots where condensation drips, where water splashes during cleaning, and cold-room floors.
• Nothing is placed on top of the unit. It would block the antenna or the vent slots and affect both the radio and the readings.

On a table the vent faces sideways. Keep the vent end well away from walls and objects so air reaches the sensor freely.

Readings can differ with position and height, even in the same room. The unit measures the air right around it, so choose a spot that represents what you are monitoring.

• Air stratifies: temperature and humidity can differ with height.
• CO₂ depends on ventilation, sources, airflow and the shape of the room. Mount the unit at the height that matters, such as where people or animals breathe.
• Avoid spots dominated by local airflow: doors, vents and air inlets.
• For temperature and humidity, mount it at the position and height of what you care about: the crop, the product or the stored goods.
• Keep it out of direct sunlight and away from heater and cooler outlets, fans, misters and cleaning water.

• A No. 2 Phillips screwdriver
• Tweezers
• The replacement battery, sensor module or filter
• A clean, dry work surface

Have the new battery ready before you open the unit. Use the type, voltage and size given on the product label or datasheet. The pictures show a D-size 3.6 V lithium battery.

Remove the eight screws on the top cover and lift it off. You do not need to remove the magnets.

1. Remove the old battery: push its + end toward the − end of the holder until the spring is fully compressed.
2. Keeping the spring compressed, lift the + end up. Once it clears the fixed contact, take the battery out.
3. Fit the new battery: hold it with − toward the spring and + toward the fixed contact.
4. Press the − end against the spring to compress it, then lower the + end and seat it under the fixed contact.
5. Check the battery lies flat in the holder, + at the fixed contact and − at the spring, and that the spring is not bent sideways. A battery fitted backwards will not start the unit.

The unit restarts by itself and rejoins the network. The first reading can take from a few minutes to several tens of minutes to appear on the dashboard. Dispose of the used lithium battery according to local rules.

The sensor module is a small board that plugs into the holder at the vent end and connects to the main board with a 4-wire cable. Hold it by the edges of the board; do not touch the components or contacts.

Remove the three screws of the sensor cover and lift it off. You do not need to remove the main board cover or the magnets.

1. Find the sensor module in the sensor chamber, and the cable running to the main board.
2. Pull the module straight up out of the holder. Do not twist it or pry against the board.
3. Pull the wire connector straight out of the socket on the old sensor.
4. Take the new sensor. The connector fits only one way: keep its flat face up.
5. Wrong way round: the keyed face with the contact windows must not be on top. If the connector is hard to push in, do not force it; turn it over.
6. Push the connector fully into the new module, push the module all the way into the holder, and check it is seated. Route the cable so the cover will not pinch it.

The new module starts reporting within 10 minutes. A CO₂ sensor can take longer before its readings settle; see Connecting to the network.

The four mounting magnets are countersunk ring magnets, each held in a recess on the base by one screw. Replace a magnet if it is cracked or chipped, or no longer holds firmly. You do not need to remove either cover.

1. Turn the unit over. Remove the center screw of each magnet you are replacing and lift the magnet out of its recess.
2. Fit the new magnet with its recessed, countersunk side facing out from the enclosure.
3. Put the screw in from the countersunk side and check that the screw head sits in the countersink.
4. Line the magnet up with its recess and screw it in, checking it sits flat. Tighten until the magnet no longer moves, and no further: the screw goes straight into the enclosure, so overtightening can damage it.