You can connect the WSC11 or WSP21 weather stations directly to the Compass controller via an RS485 connection. This article describes these different ways that that weather stations can be connected.

1. Connecting a WSC11 weather station to a Compass.
2. Connecting a WSC11 weather station to a Compass using using an extension cable.
3. Connecting a WSC11 weather station with an additional WSP21 light sensor to a Compass.
4. Connecting a WSC11 weather station with an additional WSP21 rain sensor to a Compass.
5. Connecting a WSP21 weather station to a Compass.

When the drawings show the need for an extension cable, these are the specifications for the extension cable and the required RS485 biasing and termination circuit. This is essential in RS485 networks to ensure reliable communication by preventing data errors when communicating over long distances or with multiple devices. 

1. Cable specifations - For the extension cable, make sure you use the correct wire. It must have at least the following specifications.
   1.  Wire thickness - The wire must be at least Ø 1,0 mm (0,8 mm²) or AWG18. 
   2. Twisted pairs - The wire must be at least a 6 pair twisted cable.(twelve wires total)
   3. Shielding - Each pair of cables must have their own shield.
   4. Length - The cable must be under 90 meters / 300 feet. 
   5. UV protection - The cable jacket must be UV resistant.
2. Junction box - For the junction box where the sensor cable is connected to the extension cable, make sure that it is a water tight junction box with an IP code of at least IP65.
3. RS485 termination resistor - At the junction box connect a 120 ohm ½ Watt termination resistor between the Data+ and the Data- wires as seen in the drawing above.
4. Power connections - In the drawing, you will notice that the 24 VDC power conductor and the power ground conducter are each connected to four wires. Also, in the cable specifications, you will notice that the minimum wire thickness is  Ø 1,0 mm (0,8 mm²) or AWG18. This is done to protect against voltage drop that will occur when the rain heater is on and the current load of the sensor is high.  Make sure that the power comes from the 24 VDC Compass field equipment power supply in the Compass panel.  If the required cable length is greater than 90 meters / 300 feet, it is recommended to mount a separate 24 VDC power supply close to the weather station. 
5. RS485 biasing and termination - At the Compass, include a network terminator.   Priva recommends a Loytec LT-B4 that provides biasing and the second termination resistor.  Wire the network terminator as seen in the drawing above.

Connecting a WSC11 weather station to a Compass

If you are using the 15 meter / 50 foot cable that comes with the WSC11 and do not need to extend it, you can connect the WSC11 directly to the Priva Compass and to a 24 VDC power supply.  The WSC11 comes with either a 5 conductor or 8 conductor cable. The two drawings show the wiring color of each of the cables.

Wiring colors for a WSC11 sensor with a 5 conductor cable

Wiring colors for WSC11 sensor with a 8 conductor cable

1.  
   1. Connect the supplied sensor cable with the screw coupling to the weather station.
   2. The WCS11 draws 120 milliamps. Ensure that  the 24 VDC power supply for Compass field equipment has sufficient capacity to also power the weather station. Add an extra power supply if the capacity is insufficient.
   3. Connect the wires for the power supply to the 24 VDC power supply for Compass field equipment.
   4. Connect the data wires to the RS485 port of the C4.

These components are available from Priva.

Connecting a WSC11 weather station to a Compass using using an extension cable

For distances greater than 15 metres / 50 feet, you must extend the communication cable. See notes in the introduction of the article for cable specifications. The WSC11 comes with either a 5 conductor or 8 conductor cable. The two drawings show the wiring color of each of the cables.

Wiring colors for a WSC11 sensor with a 5 conductor cable

Wiring colors for a WSC11 sensor with a 8 conductor cable

These components are available from Priva.

Connecting multiple weather station sensors to a Compass

When connecting multiple weather station sensors to a Compass, you will need a weather station connection box.  The individual sensors are wired to that connection box.  You will also need to add the biasing and termination at the Compass. You do not need to add a 120 ohm termination resistor at the weather station end of the cable since it is already integrated in the weather station connection box. Make sure you use multiple conductors for the power supply cables since there are multiple heaters in the WSP21 sensors.

Wiring colors for a connecting the weather station connection box to a Compass 

These components are available from Priva.

Commissioning multiple weather station sensors on a Priva Compass

If you have multiple weather sensors connected, you need to identify which one you will use for measurement and control. For instance if you have WSC11 weather station and you also connect a WSP21 PAR sensor, you will need to identify whether the reading from the WSC11 pyranometer or the reading from the WSP21 PAR sensor will be used for the light readings.

To select this, you will need to go to the Weather -> Configuration page. When multiple sensors are configured in the input/output configuration screen, an option will show up on the configuration screen giving you a choice as to which sensor to use. Simply choose which sensor you wish to use and Compass will configure itself for that particular sensor.

Adjusting the rain heater on the WSC11 weather station

The WSC11 has an adjustable rain heater.  You can increase the heater level if you find that the WSC11 rain detection is triggered by dew at night. You can decrease the heater level if you find that the WSC11 does not detect a light mist as rain.  

The rain heater adjustment is not available in earlier versions of the Compass. To adjust the rain heater, you need to ensure that your Compass software is at least at version 121240205 released on April 15, 2024.

In the Weather -> Configuration page, you will find a setting labeled 'WSC11 rain sensor heat level'. There are five heat levels that can be set.  VERY_HIGH_HEAT is the highest level. This will ensure that dew is not detected as rain but it may also not detect a light mist.  Also the rain heater is is close proximity to the outside temperature sensor and it may affect the outside temperature if there is no wind to dissapate teh heat. 

VERY_LOW_HEAT is the lowest level but this may not be able to differentiate between dew and rain.

There are also three intermediate levels. You can try the different levels to determine what works best in your geographic region.