*Tiny* RS232 temp sensors!

jarcher said:
Wow, 1-wire is very cool! With a CAT 5e cable, I could have 7 seperate busses and probably run it a good distance...
Click to expand...

You have to watch running too many busses in the same Cat5 cable, but you can have multiple 1-Wire devices on the same bus so the need for multiple busses running to the same location is diminished.

Eric
 
ericvic said:
jarcher said:
Wow, 1-wire is very cool! With a CAT 5e cable, I could have 7 seperate busses and probably run it a good distance...
Click to expand...

You have to watch running too many busses in the same Cat5 cable, but you can have multiple 1-Wire devices on the same bus so the need for multiple busses running to the same location is diminished.
Click to expand...

From reading the Wikipedia entry, it seems there is plenty of room on a single bus for these devices. Cat 5e almost seems like a waste of wire. The article didn;t mention a maximum practical limit for a bus though. I assume cat 5e or 6 will be better than the older stuff, but what's a good rule of thumb for these?
 
The normal maximum bus length is 300m. You don't need to use Cat6 since standard old Cat5 will work just as good. The 1-Wire bus is not very fast but is very picky about the capacitance of the line.
 
ericvic said:
The normal maximum bus length is 300m. You don't need to use Cat6 since standard old Cat5 will work just as good. The 1-Wire bus is not very fast but is very picky about the capacitance of the line.
Click to expand...

Thanks. 300m is plenty long enough for anything I would be doing. What's the best way to interface a 1-wire bus to a PC? Is there something like a USB to 1-wire converter, or serial?
 
midon said:
What's the best way to interface a 1-wire bus to a PC? Is there something like a USB to 1-wire converter, or serial?
Click to expand...

There are all sorts of devices to do this. For serial to 1-Wire, try our TEMP08 http://www.midondesign.com/TEMP08/TEMP08.html.

USB converters are available from Maxim (DS9490).

Mitch
Click to expand...
Like Mitch said, there are many adapters available to connect these to a PC (including the one in the first post). I thought I'd add that I've been using a TEMP05 (the older "version" of the TEMP08) from Midon Design and have been very happy with it.
 
Someone please correct me if I am wrong here, but one big advantage to the product that IVB purchased is you can "star" the temp sensors without the need for an additional board and power supply (as opposed to the one-wire solution which requires you to "series" the sensors).

With the one wire approach wouldn't you have to purchase a data base hub type board (to get this same "star" capability), plus additional power supplys/injectors?? I would like to see an "apples to apples" comparison/pricing with ALL one-wire equipment needed to duplicate the product mentioned by the OP! :)
 
BraveSirRobbin said:
Someone please correct me if I am wrong here, but one big advantage to the product that IVB purchased is you can "star" the temp sensors without the need for an additional board and power supply (as opposed to the one-wire solution which requires you to "series" the sensors).

With the one wire approach wouldn't you have to purchase a data base hub type board (to get this same "star" capability), plus additional power supplys/injectors?? I would like to see an "apples to apples" comparison/pricing with ALL one-wire equipment needed to duplicate the product mentioned by the OP! :)
Click to expand...

The board that IVB purchased does allow you to homerun (or star) the sensors directly. The only limitation is that you can only have one sensor for each run (as opposed to the 1-wire standards which do allow for multiple sensors on a single run - if your interface supports it). So, you are limited to four sensors but the wiring is simplified.

Other interface boards will work with multiple sensors on a single run, daisy chained, but may only have a single connection at the root. Some may have more than one connection. There are also hubs that are available (to split the daisy chain into a star pattern) as BSR mentions. In order for these to work, your interface and/or software needs to understand the hub. Again, some do and some don't.

If you want to, you can wire multiple sensors in a star pattern to a single connection (again, if the interface supports multiple sensors). However this is usually not recommended (especially for long runs) and violates the practices prescribed by Dallas Semiconductor / Maxim IC.

You can also create a star topology by using daisy-chained sensors - if you run out and back to each sensor. Run two pairs of wires from your home location to each sensor. One pair is signal and ground out to the sensor; the other is signal and ground back from the sensor. Technically, you only need the signal wire coming back, but with twisted pair it's easier/better to run both. At the sensor, you connect the signal out and signal back lines. So, your signal goes out to the sensor and then comes back along another wire. Then, you connect the "back signal" to the outgoing signal for the next sensor. You are creating much longer runs, but electrically it remains a daisy-chain instead of a star. I don't do this with my 1-wire stuff, but I do do it for my RS-485 network.

I've ignored the third wire for power here - assuming that you will be running parasitically. If you want to run power to each sensor (and some 1-wire sensors will require it), that will add another wire - but you don't have to return that to the home location if you are creating the star/daisy-chain configuration described above.
 
So there IS a CQC driver for the Qkits VK011 board that IVB got? I am will be using Elk/CQC, and want to integrate temp sensors, but like IVB's wife, I hate the Elk ones. Also, I would prefer to home-run, as the temp sensors will be in many different locations in the house.

Also, does Qkits make a humidity sensor for the same board? If not, is there a better solution that integrates both?
 
yes, there is a driver. I haven't actually mounted mine yet, but about 10ish folks went in on a group buy for these. Zaccari wrote the driver, he's been using it just fine.

I'm blanking on who, but someone is writing a 1wire driver for CQC that'll handle humidity/temp/etc. Probably best to ask over on the CQC forum about who it was & status.
 
Hi Guys

I have recently started playing with 1 wire devices and im using a ethernet based device called OPN ONE ....It talks native xPL and xAP and i have just connected a couple of Hobby Boards moisture sensors to it as well as some ds18s20 temp sensors.....Also trying to get a Hobby boards LCD to work with it....
Heres a link to opn one if interested.......

http://www.opnode.org/dokuwiki/doku.php?id=home

HTH
Frank
 
I finally put in the VK011 mini-temp sensor board. Great advantage of that is that since it was so cheap, I got 4 sensors for $75 shipped. I actually learned something too after mounting them:

I put 2 sensors in: my basement server room, and the crawlspace. Turns out those rooms aren't nearly as cold as I thought. The server room wasn't that surprising, but the 70degree temp in the crawlspace at 11:00pm at night surprised me. Now I realize why the media closet isn't getting that cool - it's drawing 70deg temp in.

I'm going to hunt down an old style thermometer to verify those temps, it certainly feels colder than 70deg down there, but i've been known to be vastly off temp wise before. If it really is 70, I may start thinking about how to pull in outside air - it's 54 deg outside right now.
 
IVB said:
I finally put in the VK011 mini-temp sensor board. Great advantage of that is that since it was so cheap, I got 4 sensors for $75 shipped. I actually learned something too after mounting them:

I put 2 sensors in: my basement server room, and the crawlspace. Turns out those rooms aren't nearly as cold as I thought. The server room wasn't that surprising, but the 70degree temp in the crawlspace at 11:00pm at night surprised me. Now I realize why the media closet isn't getting that cool - it's drawing 70deg temp in.

I'm going to hunt down an old style thermometer to verify those temps, it certainly feels colder than 70deg down there, but i've been known to be vastly off temp wise before. If it really is 70, I may start thinking about how to pull in outside air - it's 54 deg outside right now.
Click to expand...

IVB:

The quickest test will be to either swap two sensors and see if the read the same, or put two in the same room at the same location (my computer room has a 10F delta between the floor and ceiling). I have 10 1-wire sensors and they are all within 1F. I *might* calibrate them but I'm not really sure I care.
 
Cinemar just released to Beta our ML1WirePro plugin so that 1-Wire devices can be implemented within MainLobby Suite. This uses a SQLExpress database as a backend for tremendous data handling and response time to querys.

http://www.cinemaronlineforums.com/wiki/in...1WirePro_Plugin

Querys can be done via the also just released to Beta MLDatabase plugin.

http://www.cinemaronlineforums.com/wiki/in...Database_Plugin

I am looking forward to the innovative uses of 1-Wire technology that MainLobby users come up with!

One is using 1-Wire to monitor his geothermal heating system (air temps, water temps, outdoor temps, room temps, air pressure differentials, etc) and has tweeked some of the settings for energy efficiency. Hopefully he will write up some info that might help others with his analysis findings and methodologies.
 
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