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Additional Sensors, data acquisition (daq) standard needed for WUHU.

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  • wuhu_software
    For those of you that are familiar with PC Daq products, I am looking for some input as to what type of sensors to support in the future. For example, I would
    Message 1 of 1 , Dec 26, 2006
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      For those of you that are familiar with PC Daq products, I am looking for some input as to what type of sensors to support in the future.

      For example, I would like to be able to add solar radiation, leaf wetness, and soil moisture sensors to the program, while keeping the installation of those sensors as simple as possible and the overall costs to a minimum.

      Rather than supporting a bunch of different standards, I would like to write the software to support one or two at most.

      Looking at the 1-Wire stuff, it looks fairly straight forward. Other than adding the power injector ($22) that is need for some of the sensors, there are no surprises and hidden costs.

      The 1-wire stuff also has the benefit of additional sensors that could be used for other home automation projects although I am not sure if the "bus" can be accessed by more than one application at a time (a problem that is similiar to sharing a serial port). Low voltage digital inputs and outputs, and analog inputs seem to be available.

      Here is a good page that shows the variety of sensors that can be added to a 1-Wire bus.

      http://www.hobby-boards.com/catalog/main_page.php

      On the plus side, there does seem to be somewhat of a standard for weather station software supporting 1-Wire devices. Weather Display for example supports 1-Wire add-ons no matter what type of station you are running.

      The only downside I see to the 1-Wire setup is the inability to add specialized sensors. As an example, lets say we want to add a solar radiation detector, or UV-A UV-B detector (5-20ma or maybe 0-5VDC) that is not available in the 1-wire stuff.

      When you go with  1-Wire, you are basically locked in to the product line that they have available. I am not too happy with being limited by the product offerings. Who knows what type of gizmo someone might come up with (Ultrasonic wind sensor, automated snow depth measuring, etc).

      The first alternative that I have considered is some type of generic USB DAQ setup.

      Over the past few years, there have been many new offerings in this area. Some offer a variety of different digital inputs, outputs, and analog channels as well. I have seen several that are less than $100. Although some are closed to software developers (like the HOBO sensors), many have a SDK kit available (cheap or free).

      The main benefit I see to the USB Daq is that you should be able to add any type of sensor to the system. USB can also be extended with self-powered cables that would be similar to the power injectors giving you plenty of flexibility for mounting sensors.

      There are a couple of unknowns when adding a USB Daq. The primary concern I would have is the operating temperature ranges for the end Daq device and the effort required to protect it from the elements (moisture could be a big problem).

      Another downside might be that adding sensors might be a technical challenge. This might not be a big deal if there are user contributions.

      So If you have some ideas about what type of sensor network or field bus that we could standardize on let me know.

      Thanks.

       

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