1 Wire Temperature - Hooking up to multiple devices

[Teken]

I have an existing 1 wire temperature network that is currently live and working great. I have a secondary 1 wire sensing unit that arrived last week.

 

My question to those who have such devices is. Have you ever tried to connect the two system together to capture the same 1 wire temperature readings?

 

I ask because my intent was to reduce the amount of time and wiring that essentially would be duplicated in this environment.   I would really like to avoid running another 1000 feet of Ethernet CAT6 cable through out my home if I can. 

 

My initial experiment did not seem to work as I would expect.

 

Essentially, I removed from the one unit the signal (data) cable and the ground, while leaving the power attached to the other. Upon trying to enroll the sensor it came on line but registered a value of 80 plus degree's and would not move.

 

I have seen this problem on the other device but that is when you first apply power to the sensor and then it settles down.

 

1. What is the best method to share the data line between two devices?

 

2. Has anyone ever seen a problem tying in the ground wire to two different devices causing a issue?

 

 

[arw01]

Teken, if the secondary device can control one of their switch units (1 wire that is) (and I forget the part numbers) which can literally turn on or off large networks from a third network.  That sounds confusing, but it's no different than a switch instead of a hub, it literally can segment networks into manageable pieces for just this situation.

 

You can use your reading controller to turn on it's access to the network, do all it's IO and then switch it back to the other network for it to do it work, visa versa.  Just have to get your timing down so they don't try to access at the same time as one won't see it.

 

Alan's

[Teken]

Teken, if the secondary device can control one of their switch units (1 wire that is) (and I forget the part numbers) which can literally turn on or off large networks from a third network.  That sounds confusing, but it's no different than a switch instead of a hub, it literally can segment networks into manageable pieces for just this situation.

 

You can use your reading controller to turn on it's access to the network, do all it's IO and then switch it back to the other network for it to do it work, visa versa.  Just have to get your timing down so they don't try to access at the same time as one won't see it.

 

Alan's

 

Hello Alan's

 

I never really thought about it that way to be honest. But, I am unsure if I could get the two vendors to implement such a switching program behavior. Perhaps I was thinking about this problem the wrong way in that I thought I could simply tap into the sensors data line running both systems in parallel and thus capture the readings but with two separate monitoring devices.

 

I will need to ask a few more questions from the vendor get their feed back as to if this is even doable vs doing any harm to the devices in question. 

[Xathros]

I have only basic experience with these sensors myself but my belief is that it was designed for 1 host supporting many sensors not a sensor(s) supporting multiple hosts.

 

-Xathros

[Teken]

I have only basic experience with these sensors myself but my belief is that it was designed for 1 host supporting many sensors not a sensor(s) supporting multiple hosts.

 

-Xathros

 

Hello Xathros,

 

I believe you're correct with respect to the problem at hand. Maybe I just wanted my cake and eat it too!   On a very basic level their is only three wires that operate these sensors: Power, Ground, Data.

 

The 1 wire network simply relies on the fact each sensor is embedded and burned in with a unique numbered identifier. Once a monitoring device has enrolled the 1 wire sensor probe into its data base.

 

It really should not care how its being powered or grounded, so long as the data is flowing to them, no? I realized that some of the systems required the ground / data to be present. 

 

I am unsure if the problem lies with the fact one device maybe powering the 1 wire network with 3X power vs the other is using 5 volts, but don't see that being a problem. Since dozens of sensors can be powered by a host machine.

 

All I am trying to do is intercept the data from the existing 8 sensor nodes and skip rewiring the entire house again! Perhaps I will use my fall back plan and simply use the spare CAT6 wires in the existing cable and attach the new sensors into place for the new monitoring device.

 

That solution will be fine for six of the sensors but the other two I already used up the pairs for something else.   

[jsu1995]

. . . Perhaps I will use my fall back plan and simply use the spare CAT6 wires in the existing cable and attach the new sensors into place for the new monitoring device.

 

That solution will be fine for six of the sensors but the other two I already used up the pairs for something else.   

 

That was going to be my suggestion -- sensors are cheap and you should have enough conductors since you used Cat-6 cable.

 

As far as the two locations with the pairs used up; is there at least one conductor spare there?  if so, you should be able to get by with powering all of the sensors from the same voltage source and only having the two data lines separate.  You'll likely have to reference the ground to both hosts, but that shouldn't cause any issues.

[Xathros]

If it is possible, I would think that both systems would need to have the data and ground in common.

 

-Xathros

[arw01]

http://www.ibuttonlink.com/products/linkhube

 

Not exactly what you want, but the terminology should let you get to what you want.  A Hub is apparently what 1-wire uses that I called a switch, this particular device unifies different networks.  

[Teken]

http://www.ibuttonlink.com/products/linkhube

 

Not exactly what you want, but the terminology should let you get to what you want.  A Hub is apparently what 1-wire uses that I called a switch, this particular device unifies different networks.  

 

I saw that device a few years ago but that is way too much for this little project. One of the attributes for this install has been to do it on a shoe string budget that anyone could follow.

 

I never had a problem throwing money at a problem when its the only solution or is in fact the very best solution that offers great features / value.

 

I will know more what to do once I receive information from Brultech (GEM) and Autelis (ISY Bridge) makers. I did not envision more than three years ago when the 1 wire network was deployed that there would be something like the Autelis ISY Bridge that would allow me to use sensors to help control and automate my home.

 

I should have run a few more lines  .  .  .   

 

Will reply back once I know more and hope this information proves helpful to the next person.

[larryllix]

You didn't say what the two devices were but is there a way to transmit the data from the 1wire host to the other device?

 

A CAI Webcontrol board with a string of 1wire probes on it could send readings to two ISY units.

[apostolakisl]

You didn't say what the two devices were but is there a way to transmit the data from the 1wire host to the other device?

 

A CAI Webcontrol board with a string of 1wire probes on it could send readings to two ISY units.

 

This is how I would do it.  I do have a lot of experience with CAI boards and 1-wire.  CAI boards can push the 1-wire temp readings directly to ISY upon criteria of your choice within the cai programming.  The cai can handle 8 1-wire sensors at a time.  I just assumed you want the temp readings in ISY, but I don't know what the other thing(s) is/are and thus can't say if CAI would be able to provide that(ose) devices with the values as well . . . at least directly.

[Teken]

You didn't say what the two devices were but is there a way to transmit the data from the 1wire host to the other device?

 

A CAI Webcontrol board with a string of 1wire probes on it could send readings to two ISY units.

 

 

This is how I would do it.  I do have a lot of experience with CAI boards and 1-wire.  CAI boards can push the 1-wire temp readings directly to ISY upon criteria of your choice within the cai programming.  The cai can handle 8 1-wire sensors at a time.  I just assumed you want the temp readings in ISY, but I don't know what the other thing(s) is/are and thus can't say if CAI would be able to provide that(ose) devices with the values as well . . . at least directly.

 

The CAI board was one of the first devices I was going to use for my 1 wire expansion. From what I have seen and read on this forum and many others is this device is very powerful in its own right and has lots of capability in many areas. Unfortunately, as stated the CAI only supports eight 1 wire temperature sensors.

 

Therefor I opted to go with the Autelis Bridge as it supports 32 channels and humidity. It is also a serial bridge adapter for any related 3rd party devices which allows ISY integration all in one box. After a marathon install this past week end, I ran another mile of CAT6 Ethernet cable through out my home to prep and ready all 32 sensors.  

 

The only saving grace was having the spare (pairs of CAT6) wires in place and this allowed me to measure the same areas / zones with out running duplicate wiring!

 

Below is a quick (temporary) set up of the current system in place. The initial ten 1 wire sensors I received from China were simply perfect and accurate (all on a shoe string budget)! Testing all of the sensors at the same time showed the largest variance between any two sensors was 0.1 to 0.3 degrees. 

 

From -30'C all the way to 125'C all showed 0.1 to 0.3 variance which is simply stellar in any book!

 

After receiving feed back from Autelis / Brultech I decided to go with duplicating the wire runs to avoid any possible damage to either systems. It took a lot of sweat equity during the last three days but it will pay off in spades once I am able to pump the data into the ISY and then control the Insteon network!.

 

My five year dream of fully automating my home based on local environmental data is finally coming true, and have Autelis, Brultech, Insteon, and UDI, to thank! Many more updates in my install thread with lots of photos, video's, and trials and tribulations of success / failures in my install.

 

Thank you all for your insight, feed back, and endless support in my endeavors!

[io_guy]

Another option is a Raspberry Pi and a Sheepwalk module.

http://www.sheepwalkelectronics.co.uk/index.php?cPath=22

These are hardware based, not bit bangers.

A lot of use use the RPI2, but the RPI3 is also available for massive networks.

[Teken]

Another option is a Raspberry Pi and a Sheepwalk module.

http://www.sheepwalkelectronics.co.uk/index.php?cPath=22

These are hardware based, not bit bangers.

A lot of use use the RPI2, but the RPI3 is also available for massive networks.

 

Hello io_guy,

 

The Raspberry Pi was one of the first products that caught my attention from the onset. I may still purchase one as it offers lots of flexibility for me in the not too distant future.

 

The vendor at the sheep walk electronics is actually where I intended to purchase the 1 wire humidity sensors!  Once I am able to complete the remaining temperature sensor install that will be my next purchase and project goal. Just trying to figure out what is going on with my ISY / Autelis Bridge first before I commit to another task.

 

I really do wish someone in North America sold the same 1 wire humidity sensor kit!   The exchange rate is simply killing me and is out of this world, given the low dollar exchange. 

[larryllix]

The SWE3 module is based on the DS2438z which will  give you temperature as well as humidity. This was an unexpected bonus for me and eliminated some extra wiring connections at the top on my weather pole.

[Teken]

The SWE3 module is based on the DS2438z which will  give you temperature as well as humidity. This was an unexpected bonus for me and eliminated some extra wiring connections at the top on my weather pole.

 

Hello Larryllix,

 

Yes, that was something that caught my eye from the onset! It will be a perfect solution for the two bathrooms, basement, central home, and outside. Can you share with me what type of enclosure you placed the unit in? Also, which of the three package options did you buy and what was the total costs from shipping, exchange, duties / tax's to Ontario?

[larryllix]

Hello Larryllix,

 

Yes, that was something that caught my eye from the onset! It will be a perfect solution for the two bathrooms, basement, central home, and outside. Can you share with me what type of enclosure you placed the unit in? Also, which of the three package options did you buy and what was the total costs from shipping, exchange, duties / tax's to Ontario?

The CAI board came with a case and with shipping came to about $70

http://www.ebay.com/itm/WebControl-timer-temperature-humidity-I-O-controller-HW-2-2-2-/260849255154?pt=LH_DefaultDomain_0&hash=item3cbbd3c2f2

 

I ordered the SWE3 and the RPi 1wire adapter, just in case I switch to the Rpi later. With shipping and all that came to about $105.

 

Note: There is no duty charged coming into Canada, under $200 they will not even bother to stop packages. Don't fall for the latest eBay, "Worldwide Shipping" money grab scam.

[Teken]

Larryllix,

 

How are you going to power the SWE3 to obtain the required 5 volts? Are you powering it externally or via the CAI board? I believe in my environment I will need to power the SWE3 board externally as the Autelis Bridge only outputs 3+ volts on the power line. If anyone has a suggestion or a link to the following it would be most helpful.

 

Looking for a 9 volt to 5 volt converter so I can use a standard 9 volt battery (must be small form factor). Or a actual 5 volt battery pack power supply. The one I found on EBAY was a little expensive considering I need to power four of these once I am all done. Unless one of these can power all four then its all good.

 

Looking for something small I can place all into one small project box and has long battery life. This whole temperature / humidity project is starting to go a little over budget! 

[larryllix]

The CAI board has three terminals for 1wire, 5V, data,and common. These feed the CAI board and any other 1wire devices on that 3wire bus.

 

The CAI board has a recommended 9v power supply to a 7805 regulator. I am told I can just wire into the interface (1wire or humidity sensor terminal) with a 5v power supply like a getting to be standard microUSB / USB power supply. I haven't tried this and to be in parallel with a regulator chip output, I am not too sure about. At 9v the regulator runs hot but tolerable. I recommend gluing a heat sink onto it, especially if over 9v. I run 9-10v and it's hot without the sink. 7.5 may have worked better but harder to get and if the whole thing gets scrapped the 9v adapter works for the Insteon MSs.

 

The SWE3 contains two chips, ie. humidity sensor (optional in purchase) and battery monitor chip. I think the spec says these chips will operate at very low voltages. Not sure about 3v without researching chip specs. BTW: this battery monitor contains a temp. sensor (0.1c resolution), voltage A/D for the humidity chip or other  input via terminals provided, and a current accumulator A/D input that is designed for keeping track of current charging and draining in a battery. Thus the battery monitor name.

 

The CAI board is well suited to these small jobs as a peripheral to the ISY. I have some reboot problems with mine so far but the CAI_support is working on it and has done some mods in the firmware. I may have a noisy PS but I have been too lazy to get the scope out, so far, and expecting a better switching wallwart replacement soon.

 

The main reason I went CAI is the 2MHz counter in hardware on the board, that works excellent for my anemometer, and 1wire I/f.

[io_guy]

You need 5V to supply the 1-wire interface, 3 won't cut it.

When I used a CAI I added an external 5V supply because it was quite unstable pulling off the terminal.

I also had to add pull resistors at each sensor location - the bit-banging is a little fussier for signal quality than the hardware 1-wire chips.

[Teken]

The CAI board has three terminals for 1wire, 5V, data,and common. These feed the CAI board and any other 1wire devices on that 3wire bus.

 

The CAI board has a recommended 9v power supply to a 7805 regulator. I am told I can just wire into the interface (1wire or humidity sensor terminal) with a 5v power supply like a getting to be standard microUSB / USB power supply. I haven't tried this and to be in parallel with a regulator chip output, I am not too sure about. At 9v the regulator runs hot but tolerable. I recommend gluing a heat sink onto it, especially if over 9v. I run 9-10v and it's hot without the sink. 7.5 may have worked better but harder to get and if the whole thing gets scrapped the 9v adapter works for the Insteon MSs.

 

The SWE3 contains two chips, ie. humidity sensor (optional in purchase) and battery monitor chip. I think the spec says these chips will operate at very low voltages. Not sure about 3v without researching chip specs. BTW: this battery monitor contains a temp. sensor (0.1c resolution), voltage A/D for the humidity chip or other  input via terminals provided, and a current accumulator A/D input that is designed for keeping track of current charging and draining in a battery. Thus the battery monitor name.

 

The CAI board is well suited to these small jobs as a peripheral to the ISY. I have some reboot problems with mine so far but the CAI_support is working on it and has done some mods in the firmware. I may have a noisy PS but I have been too lazy to get the scope out, so far, and expecting a better switching wallwart replacement soon.

 

The main reason I went CAI is the 2MHz counter in hardware on the board, that works excellent for my anemometer, and 1wire I/f.

 

 

You need 5V to supply the 1-wire interface, 3 won't cut it.

When I used a CAI I added an external 5V supply because it was quite unstable pulling off the terminal.

I also had to add pull resistors at each sensor location - the bit-banging is a little fussier for signal quality than the hardware 1-wire chips.

 

 

Thanks guys for the quick follow up and insight. I believe I am going with a something like this for the external powering of the SWE3 device(s):  http://www.ebay.com/itm/310670105406?ssPageName=STRK:MESINDXX:IT&_trksid=p3984.m1436.l2649

 

This is just one example of PSU's I have been looking into. I will try one out and place it on the bench for a few weeks before I commit to anymore. For $3.45 can a guy really go wrong? 

 

Any other input is greatly appreciated!

[larryllix]

That units looks good if you wanted to have 12v battery backup.

 

My CAI board puts out 5vdc on the 1wire terminals.

 

Make sure you get hardware 2.2.2 (current) and v2.03.17 or newer. The firmware is updatable without returning the board. Shipping costs are the prohibitive factor in this game.

[io_guy]

Yea, I saw you were mentioning a 9V battery for power.

I'm doubting it will last very long, they typically are rated around 500 mAh.  You're likely pulling a couple watts with the CAI and sensors.

[Teken]

Yea, I saw you were mentioning a 9V battery for power.

I'm doubting it will last very long, they typically are rated around 500 mAh.  You're likely pulling a couple watts with the CAI and sensors.

 

This device indicates it can provide 2 amps  continuous at 15 watts. I believe that is more than enough to power one SWE3 unit never mind four. I am always about over kill so worst case four of these will power the 4 SWE2 sensors externally and it costs me no more than $13.80 USD.

 

That won't break the bank in this project!   

[larryllix]

This device indicates it can provide 2 amps  continuous at 15 watts. I believe that is more than enough to power one SWE3 unit never mind four. I am always about over kill so worst case four of these will power the 4 SWE2 sensors externally and it costs me no more than $13.80 USD.

 

That won't break the bank in this project!   

The energy still has to come from somewhere and the device linked to doesn't store or produce power.  Again if you are considering running the CAI off a 9v battery it should last about an hour. We haven't touched the Peukert factor.

 

The main SWE3 sensor chip is the DS2438z chip rated at 50-100uA but even a 10K pullup is going to draw 0.9mA not to mention the HIH-40xx humidity sensor. With a 2mA draw you could expect about 250 hours= 10 days out of a 9v battery rated at 500mAh

 

.http://datasheets.maximintegrated.com/en/ds/DS2438.pdf