Lacrosse WS3600 Weather Station
Some Technical Details of the Rain Gauge
Thermo-Hygro Cabled vs Wireless Behaviour
The rain gauge cable was lengthened a few metres. The wind sensor cable was lengthened by perhaps around 10 metres.
Outdoor Temperature & Humidity Sensor
Rain Gauge
This shouldn't be on the roof (readings potentially affected by high winds) but I couldn't find anywhere else that I could wire to that wasn't either affected by a rain shadow (from building, fence or bush) or sprinklers.
Wind Sensor
The wind sensor should be much higher (theoretically 10m above ground) but I think this will suffice. There is nothing taller for 40 or 50m, and even then that is only a few thin trees.
Electrical
The reed switch is open circuit at each of the rest positions, and closes as the see-saw tips. This means you cannot use a multi-meter to test the wiring and switch with the rain gauge at rest (because the switch is open-circuit and looks the same as a broken wire).
If you have the cable unplugged and you connect your meter (on the Resistance or Ohms setting) across the outer cores of the plug (or across the reed switch) and dribble water into the gauge, the switch should close long enough to cause the meter to flicker or beep (it closes for between 110 and 150 milliseconds each tip). If it doesn't, remove the cover and position the see-saw mid-way with your fingers and check again. In this position, you should see a few ohms or less. (If not, the reed switch is probably faulty.)
If you have the cable plugged in, you should measure about 3V across the ends of the reed switch with the see-saw at both rest positions. As the see-saw starts to tip, you should measure 0V until it reaches the other rest position. As mentioned above, when it tips normally with water, the switch only closes for a very short period of time. Most meters will not have to time show 0V, but will probably flicker as the see-saw tips.
Mechanical
3.5 cm3 (or 3.5 milli-litres) of water should cause the rain gauge to tip and register 0.51mm of rain.
The reed switch in the rain gauge failed. I replaced it with another switch the same length (14mm) purchased from a local electronics shop but it gave multiple registrations for a single "tip" of the buckets - particularly if water was dribbled into the gauge quite fast.
On investigating, I found that the "see-saw" had a small amount of movement along its axis (the hinge point). If it was slid close to the reed switch, the switch failed to open when the buckets were at rest in one of the 2 rest positions. If the see-saw was slid as far as it could go away from the reed switch, all was well.
I tried re-positioning the reed switch 5mm higher up the PCB. Although this solved the problem of the switch being closed at the rest position, it opened at the mid-point of the movement (which would have resulted in 2 registrations for each tip of the buckets).
I eventually installed a shorter (10mm) reed switch. I was able to install it such that it always opened at the rest position (although when the see-saw was close to the switch, it only just opened).
I recommend that if you replace the reed switch, you carefully check that:
Note there is no need to apply any pressure when moving the see-saw sideways on its axis - just very gentle pressure.
Some technical details of the rain gauge:
Rain gauge with cover removed
View from reed switch PCB side (with wires un-soldered)
Reverse side of the PCB showing the 14mm reed switch
PC Data Cable
Note that although this does look peculiar (no connection to RD for example) - it is correct. The WS3600 does not use an asynchronous serial protocol (ie normal RS232 serial as used by PC serial ports). Instead it uses a synchronous protocol using the handshake lines.
| RS232 Function | DB 9 Female | RJ12 |
| CD | 1 | n/c |
| RD (to PC) | 2 | n/c |
| TD (from PC) | 3 | 2 |
| DTR (from PC) | 4 | 3 |
| 0V | 5 | 1 |
| DSR (to PC) | 6 | 5 |
| RTS (from PC) | 7 | 4 |
| CTS (to PC) | 8 | 6 |
| RI (to PC) | 9 | n/c |
Thermo-Hygro-to-Display Wiring
This cable needs a "cross-over" (ie 1->4, 2<->3, 3->2, 4->1.
Wind & Rain Sensor Wiring
Thermo-Hygro Cabled vs Wireless Behaviour
When the Thermo-Hygro unit is communicating with the base station (display) via wireless, a little icon (perhaps looking like radio waves) appears to the right of the outdoor humidity display when the base station is interrogating the thermo-hygro unit. The icon stays displayed for 5-6 seconds each time it communicates, and display data updates at the end of this time. If the wind speed is below 10kph, the base station transmits every 128 seconds. If the wind speed is above 10kph, it transmits every 32 seconds.
When the thermo-hygro unit is cabled to the base station, the little icon is never displayed. The display updates at the same rate as described above (when communicating via wireless).