Description of the 310MHz RFXSensor Type-3.

The RFXSensor unit is a wireless battery powered temperature sensing transmitter with one hard-wired temperature sensor and optional wired external sensors.
This RFXSensor Type-3 can have up to 7 external wired sensors connected. All RFXSensor units are available with a 310MHz or 433.92MHz transmitter.
The RFXSensor unit transmits a 32 bit RF data packet (three times for redundancy) with each temperature change as described below. This data format can be received by the RFXCOM X10 receivers or a W800RF32 receiver. When used with the proper software the temperature and optional sensor data can be remotely decoded and displayed or used to control other devices.
The software to interpret the data packet can be user written or standard home automation software like Homeseer and the RFXCOM or ACRF plug-in can be used.
The RFXSensor unit uses one of two user-selectable sensitivity and transmission rates; high and low.
When the high rate setting is used the RFXSensor unit will measure the temperature for each attached sensor every minute and report any changes of .5 degrees C or higher. If a change of .5 degrees or higher has not been detected for 40 minutes the current temperature will be transmitted as a keep-alive or heartbeat signal. This setting allows for frequent temperature updates but will consume more power and result in a shorter battery life.
When the low rate setting is used the RFXSensor unit will measure the temperature for each attached sensor every 5 minutes and report any changes of 1 degree C or higher. If a change of 1 degree or more has not been detected for 80 minutes the current temperature will be transmitted as a keep-alive or heartbeat signal. This setting provides less frequent temperature updates but will provide the longest battery life.
The RFXSensor Type-3 uses a DS2438 temperature sensor which is able to measure temperatures from -40˚C to +85˚C (-40˚F to +185˚F) with an accuracy of van ±2˚C between -10˚C to +85˚C.
The RFXSensor units have an operating temperature of -10˚C tot +45˚C. For external sensors the operating temperature of the sensor counts.
The RFXSensor Type-3 units are powered by a 9 Volt battery. It is also possible to connect an external 9 volt DC adaptor to the battery clip. If a large number of external sensors is connected it is advised to power the RFXSensor Type-3 by a 9V DC adaptor.
The wired external sensors can be connected to the unit with a standard 3.5mm - 3 pole jack connector.
Each RFXSensor unit has an address allowing to use more RFXSensors at the same time within range of each other.

The A/D input of each DS2438 can be used for a humidity sensor, a barometer pressure sensor or can be used to measure a DC voltage within the range 0 - 10Volts.

Capabilities:

• Standard one temperature sensor connected.

• Additional Temperature, Humidity and Barometer pressure sensors available.

• External wired sensors can be connected using a standard 3-pole connector.

• External sensors of type DS18B20 and DS2438 are supported.

• Each sensors is seen by software as an individual one.

• The cable of the additional sensors can be extended up to 10 meter.

• All sensors use the 1-Wire® interface. (3 wires and long distance)

• Automatic sensor detection during initialization.

• Temperature measurement from -55˚C to +125˚C (-67˚F to +257˚F)

• Accuracy up to 0.5˚C

• The A/D input of each DS2438 can be used for your own requirements

• Transmitter range > 100ft

• Transmit frequency 310MHz

• 1 RFXSensor can have internal and up to 7 external sensor

• Up to 8 RFXSensor devices can be active in one configuration.

• So, a total of 64 sensors can be active in one configuration.

• Battery powered or with an external 9V DC power adapter.

Firmware revision history:

Version 2

• first production version RFXTemp using the DS1821

Version 3

• 32 bits format

• sample every minute temperature and transmit if different from previous reading

• 0.5 degrees accuracy

• transmit at least ones per 40 minutes

• sampling time changed from 108 to 126ms

• inter packet gap changed from 40 to 36ms

Version 4

• only DS18B20 multi supported

• address generated by RFXtemp

• selectable sample time

Version 5

• transmit serial numbers of each sensor found during reset

Version 6

• name changed to RFXSensor

• message format changed

Version 7

• power to 1-wire 18ms before start new temp sampling

Version 8

• support for DS2438 added

Version 9

• error corrected in 9 bits temp check

Version 10

• error corrected in parity generation for info packets