Analog Inputs
- Thread starter Mark42
- Start date
I had hoped to avoid this but I have indeed ordered the parts required to build a general purpose analog input card. The DS2450 is still available but only as an surface mount device making fabrication somewhat more difficult.
It will be interesting to see how well it actually performs; the DS2450 appears to only have a single ground for both 1-Wire and the common sensor return. I will be hooking up some copper clad thermistors which will be attached to the furnace hot water supply and return lines.
On reflection, the HVAC card would not have worked for me anyway, looking at the ADC input circuitry, the card is specifically designed for 24VAC input (as you might expect from the name I suppose
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It will be interesting to see how well it actually performs; the DS2450 appears to only have a single ground for both 1-Wire and the common sensor return. I will be hooking up some copper clad thermistors which will be attached to the furnace hot water supply and return lines.
On reflection, the HVAC card would not have worked for me anyway, looking at the ADC input circuitry, the card is specifically designed for 24VAC input (as you might expect from the name I suppose
.apostolakisl
Senior Member
I was talking to the guys at cai. They tell me the latest firmware supports the ds2450 (adding more analog inputs to the unit) but also confirmed that there were issues with noise requiring a fair amount of tinkering to clean it up.
Thanks for the responses. I have successfully built and added a DS2450 circuit to my existing Midon TEMP08 1-Wire system. I currently have 4 thermistors being monitored in HomeSeer via this link. The readings are a bit coarse as the TEMP08 only operates the DS2450 in 8 bit / 5.12V mode but it's adequate for my current needs. Noise does not appear to be a problem at this resolution .
.<<DS2450 is very sensitive to noise. Make sure use a lot of capacitors to filter the power and input lines.>>
I now understand your comment. I assumed you were referring to noise in the ADC results, I now see you were referring to the communications to the DS2450? I'm seeing errors about 30-50% of the time only on the DS2450, all the other 1-Wire sensors are fine. If the DS2450 is that sensitive, I wonder if the fact my circuit is on a wireless breadboard makes it more susceptible? I have tries various capacitors (and a 100 Ohm resistor in series on the DQ line) but nothing so far seems to decrease the reported error rate.
Any suggestions as to what size/type capacitors and where? TIA.
I now understand your comment. I assumed you were referring to noise in the ADC results, I now see you were referring to the communications to the DS2450? I'm seeing errors about 30-50% of the time only on the DS2450, all the other 1-Wire sensors are fine. If the DS2450 is that sensitive, I wonder if the fact my circuit is on a wireless breadboard makes it more susceptible? I have tries various capacitors (and a 100 Ohm resistor in series on the DQ line) but nothing so far seems to decrease the reported error rate.
Any suggestions as to what size/type capacitors and where? TIA.
Like Lou said, CAI's WebControl now supports DS2450, according to WebControl 3.2.9 document, 100PF disc capacitor from any pin to ground, plus 1K input resistor on each ADC channel. You can read their document on their site. Which controller do you use to talk to DS2450 chip?
That document URL is here:
http://www.cainetworks.com/manuals/webcontrol/WebControlPLCUserGuide3-02-09.pdf
On its last page, it talks about DS2450
http://www.cainetworks.com/manuals/webcontrol/WebControlPLCUserGuide3-02-09.pdf
On its last page, it talks about DS2450
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