Michael McSharry
Active Member
Marc,
I think you did a good summary of the state of what we know about the WebControl ability to do temperature measurements. I though it would be difficult to do much evaluation independent of CAI so I am curious and anxious to see what you do discover.
The only hardware interface that I have where I can control the software is the DS9097U and that is not a good unit to evaluate the WebControl because the interface is different in a critical area that allows the sensor to used without external power. If the WebControl is going to be used to interface the sensor under test then there is a lack of visibility in the timing as viewed by the firmware.
In the past when I scoped my 1-wire I saw that is was quite tolerant of variation due to line capacitance, but easily disturbed with reflected signals when branches were added. I was observing in a worst-case capacitance scenario a sawtooth-like waveform and was still able to make temperature measurements. Even with this evidence I still ran my wiring to minimze the capacitance.
It is nice that CAI has been very willing to interact on a engineering level, however they do seem to have a mindset that there is nothing wrong with their 1-wire interface design and the problems are all introduced by the user because of poor quality sensors or power.
I had sent CAI a sensor where the ROM code could not be detected and one where the sensor would lock up after awhile when powered externally. Never got any feedback on the first and they returned the second one after a short amout of testing where it did not lock up for them. They just attributed it my 5v regulated/filtered power vs their bench power. The sensor that locked up was a known Dallas-produced sensor circa early 2000's when Maxim-ic's pricing structure did not distinguish middle-men vs. end user. I though this would have been a very valuable test resource to help them isolate the issues with their firmware. I kind of gave up interacting with them after that.
I think you did a good summary of the state of what we know about the WebControl ability to do temperature measurements. I though it would be difficult to do much evaluation independent of CAI so I am curious and anxious to see what you do discover.
The only hardware interface that I have where I can control the software is the DS9097U and that is not a good unit to evaluate the WebControl because the interface is different in a critical area that allows the sensor to used without external power. If the WebControl is going to be used to interface the sensor under test then there is a lack of visibility in the timing as viewed by the firmware.
In the past when I scoped my 1-wire I saw that is was quite tolerant of variation due to line capacitance, but easily disturbed with reflected signals when branches were added. I was observing in a worst-case capacitance scenario a sawtooth-like waveform and was still able to make temperature measurements. Even with this evidence I still ran my wiring to minimze the capacitance.
It is nice that CAI has been very willing to interact on a engineering level, however they do seem to have a mindset that there is nothing wrong with their 1-wire interface design and the problems are all introduced by the user because of poor quality sensors or power.
I had sent CAI a sensor where the ROM code could not be detected and one where the sensor would lock up after awhile when powered externally. Never got any feedback on the first and they returned the second one after a short amout of testing where it did not lock up for them. They just attributed it my 5v regulated/filtered power vs their bench power. The sensor that locked up was a known Dallas-produced sensor circa early 2000's when Maxim-ic's pricing structure did not distinguish middle-men vs. end user. I though this would have been a very valuable test resource to help them isolate the issues with their firmware. I kind of gave up interacting with them after that.
