DS2438 sensor support

[CAI_Support]

We are releasing this new firmware for hw rev 2.2.2 board to add support for DS2438 sensor.  Once DS2438 sensor is attached to the 1-wire bus and configured through temp sensor configuration screen, it will have voltage and current reading stored in AIP5,6,7,8 for up to two DS2438 sensors.

For wc8 hardware rev 2.2.2 board, please update with this firmware
http://www.cainetworks.com/support/download/wc8plc030230-update.zip

This update included DS2438 sensor support. In addition, two PLC commands are added.
V2RH a b c #where a is ADC output, can be AIP5, for example; b is supply voltage to Honeywell humidity sensor, can be 497 == 4.97V, c is result
RH2RHT a b c # where a is humidity reading, b is temperature reading 0.1 degree, 20.1c = 201. c is the temperature calibrated humidity result.


Please provide your feedback.  This support will be added to newer WC8 hw rev 2.3.8 board also, but as a user update firmware. Default shipping will still be current 3.03.27 firmware.

 

[CAI_Support]

Example for those two commands usage:

START    
	V2RH AIP5 497 VAR1 
	RH2RHT VAR1 T1 VAR2 
END

 

[rossw]

Can you explain what is "temperature calibrated humidity" in this context?
Or is this fine-tuning the HIH4000 series sensors? (Is their temperature compensation inadequate?)
 
I stopped using the HIH-5000 sensors because of their cost and difficulty to get, and been using the AM2320 series. They're more accurate and combine both functions in one chip. If there was an inexpensive source of HIH-5000 I would consider going back to them if these new commands provide similar results.

 

[CAI_Support]

If you look the Honeywell HIH4000 data sheet, it stated that relative humidity and calculation for the temperature impact. Relative Humidity is already considered temperature impact at certain degree of its measurement. But that is not totally compensate over whole temperature range. Honeywell provides a formula to better calculate the real relative humidity affected by temperature change.
 
Not know if AM2320 provides similar formula. If so, it can be used, too.

 

[CAI_Support]

We are seeking feedback on the hw rev 2.2.2 boards running the 3.02.30 firmware, to see how people using the DS2438 sensor on their 1-wire bus. If the demand is not high, we may not port that feature to other rev boards.