damage
Senior Member
you can do anything w/ rrdtool (samples http://oss.oetiker.ch/rrdtool/gallery/index.en.html ) takes some learning
Temprature Monitoring
- Thread starter rnichols430
- Start date
toymaster458
Active Member
The Analog Voltage output range is 0-5 volts. Here is the Standard Curve Lookup
BraveSirRobbin
Moderator
So it appears that the output is not linear (i.e. no way to establish a linear slope/intercept equation).
rnichols430
Member
So what would I need for this Homeseer setup?
hult
Active Member
As with all such simple (non-linearized) thermistors, the relationship between temperature is non-linear so as Kirk suggests, a lookup table is a straightforward, useful approach.
Alternatively, given adequate computing resources, the temperature value can be computed 'on-the-fly' using the Steinhart-Hart relationship (Google: Steinhart-Hart) which can be truncated to the three terms:
T= 1/( A + B*ln( R ) +C*(ln( R ))**3)
ABIK, Kanak Solutions doesn't provide the user/purchaser of the DATANAB devices the required three S-H coefficients (A, B, C) but they can be calculated from three well-spaced, accurately known temperature-resistance pairs. And the DATANAB'S 10K THERMISTOR appears to be a house-branded Betatherm 10K3A1B device. See http://www.betatherm.com/datasheets/datasheet.php?p_id=66# . Betatherm has already calculated the coefficients for us, so armed with knowlege that the DATANAB parts are in fact Betatherm 10K3A1B's, we can refer to Betatherm's table at http://www.betatherm.com/steincoeff.htm for the required constants.
HTH ... Marc
BraveSirRobbin
Moderator
Thanks for the reply Marc;
I guess you could use the listed equations you show above, but I was hoping for a simpler setup. I was looking at THIS Phidgets temp sensor (as suggested above) as it uses voltage output in the range of five volts. I was hoping this would minimize line/noise problems when connecting these sensors over long wire lengths. I'm not sure what they use for the sensor itself (maybe LM35 solid state amplified with circuitry on that board??) but it seems of comparable accuracy to the thermistors, and linear.
Interested in your opinion!
I guess you could use the listed equations you show above, but I was hoping for a simpler setup. I was looking at THIS Phidgets temp sensor (as suggested above) as it uses voltage output in the range of five volts. I was hoping this would minimize line/noise problems when connecting these sensors over long wire lengths. I'm not sure what they use for the sensor itself (maybe LM35 solid state amplified with circuitry on that board??) but it seems of comparable accuracy to the thermistors, and linear.
Interested in your opinion!
hult
Active Member
Thanks for the reply Marc;
I guess you could use the listed equations you show above, but I was hoping for a simpler setup. I was looking at THIS Phidgets temp sensor (as suggested above) as it uses voltage output in the range of five volts. I was hoping this would minimize line/noise problems when connecting these sensors over long wire lengths. I'm not sure what they use for the sensor itself (maybe LM35 solid state amplified with circuitry on that board??) but it seems of comparable accuracy to the thermistors, and linear.
Interested in your opinion!
The 1140 Precision Temperature Sensor from Phidget you reference uses an Analog Devices AD22100K "Voltage Output Temperature Sensor
with Signal Conditioning" IC. Data sheet here
IIRC, this IC has been available for about 15 years. It is the built-in amplification and level-shift of the built-in band-gap temperature sensor and output buffer ("conditioning") that functionally distinguishes it from National's even older LM34 and LM35 devices. AD also claims an intrinsic ratiometric "nature" which consists in using the same power supply for the device as is used for the Analog-to-Digital converter (ADC) voltage reference.
The -K suffix device used by Phidget is a spec'd at initial error of +/-0.5 C (typical ) to +/-2.0C (max) which accords with data sheet you cite. Accuracy in actual use will also depend on the errors associated with the ADC.
As long as the device(s) is/are stable with time, one can calibrate out initial errors if one has access to the y=mx +b constants in software ( Temperature = Voltage * Gain + Offset) where Gain = "slope" = m and Offset = "y-intercept" = b ).
The Phidget device puts the SOIC package of the IC, two capacitors, a resistor and connector on a PCB at the moderate cost of $15 + $2 cable = $17 per sensor. One can solder up the equivalent thing with no PCB and no connector for about $4 using a TO-92 package device (from www.digikey.com part AD22100KTZ-ND at $3.31 each) and caps and resistor. I'm not revealing anything proprietary here: Phidget's sensor is a no-frills direct implementation of Analog Devices's product.
FWIW, I've developed a (preliminary, not tested) multi-channel input PCB that alllows for general purpose mx+b ("linear") scaling, signal buffering and local conversion of the sensor data to 1-wire as well as conditioned (eg 0-5 vdc) analog output. See description and schematic and PCB layout
... Marc
Visit my ongoing Home Automation and Electronic Internet Porch Sale at www.ECOntrol.org/porch_sale.htm
toymaster458
Active Member
For the DataNab 10k thermistor the three required parameters are:
A=1.1292x10-3
B=2.3412x10-5
C=8.7674x10-8
I can also email you the Equations PDF on the thermistor that is used if needed.
hult
Active Member
Kirk,
Thanks for that information. It agrees as-close-as-makes-no difference with the Betatherm reference I cited in my previous post. Perhaps (I'm guessing) yours are calculated from other than 0C, 25C and 50C values.
And thanks too for making available a broad range of thermistor-based sensors at affordable prices !
Just the breadth of mounting options shown should be iuseful to many Cocooners in selecting a long-lasting probe that doesn't cause maintenace problems and has a thermal time constant appropriate to the data objective and environment.
... Marc
ginigma
Active Member
Take a look at the Fusion Brain. It has 10 analog inputs, USB connectivity to a PC, they have temp sensors (and others).
I built a very simple UI and have it displaying temp for a few sensors.
It will log to an XML file format, so you can bring it into Excel real easy and create graphs.
The site: http://www.fusioncontrolcentre.com/FusionS...talog/index.php
Huge forum with more info than you can digest: http://www.mp3car.com/vbulletin/fusion-brain/
I haven't completed all my integration yet, but here's my simple interface:
I built a very simple UI and have it displaying temp for a few sensors.
It will log to an XML file format, so you can bring it into Excel real easy and create graphs.
The site: http://www.fusioncontrolcentre.com/FusionS...talog/index.php
Huge forum with more info than you can digest: http://www.mp3car.com/vbulletin/fusion-brain/
I haven't completed all my integration yet, but here's my simple interface:
I would like to start using some temp sensors also. But I'm still a little confused. What do I buy that hooks up to the computer? Is one wire accually one wire or one cat5 per sensor? Is there a plug in play system that doesn't require some of the tech. stuff discussed in this thread. How about wireless sensors?
thanks
Lance
thanks
Lance
damage
Senior Member
there are "wireless" 1 wire sensors http://www.rfxcom.com/sensors.htm#RFXSensor
they talk to the rfxcom or wgl 800 receivers
they talk to the rfxcom or wgl 800 receivers
toymaster458
Active Member
Are you looking at integrating into a current system or is this going to be a stand alone application. If you are looking to integrate, you may want to look and see what options are currently available for the controller you have and then go from there.
