WebControl: $35 Web- and email-enabled data acquisition and control

[sic0048]

So with the modification is the device reading temps more accurately? I haven't followed the progress too closely, but it seems the device wasn't too accurate in the beginning. Have those issues been worked out?

 

[pete_c]

Better - I am testing with a Midon combo temp/humidity 1-wire sensor about 20 feet from the CAI webcontrol sensor at this time. The webcontrol sensor is near the basement floor and the combo is in the ceiling rafters.

CAI temp is 68.9 and combo is 66.0F / CAI humidity is 68.9% and combo is 66% on web captures shown in pictures. I have the current combo temp/humidity Midon sensor connected to a 9097-1wire network.

Adjacent to the CAI webcontrol device I have another "test" Temp08. Will get getting another HB combo temp/humidity sensor shortly and will connect it to the adjacent Temp08 device so that the two sensors are literally inches from each other.

 

[Michael McSharry]

I have tried a number of solutions for temperature measurement and found the only thing that makes a consistent difference is the specific DS18B20 that is being used. This ranges from some that the WebControl cannot even read, others where it reads for awile and then the value freezes, others where there is several degrees of error. The DS18B20 probe from ebay that is encapsulated in a small stainless bullett and has a few feet cable with connector has worked very well for both that I obtained. It looks like the encapsulation it is waterproof also so good for a variety of applications.

The chart shows in pink the WebControl reporting and the green shows a DS9097U interfaced DS182B0. Variance is within the published specs of the DS18B20.

My take on it at this time is that you need specific versions of the DS18B20 that willl work with the firmware that the WebControl implements. While CAI is making changes to the firmware I never had any positive indication that they will redesign to use parasitic power.

I never had any issue with the humidity so I did not do as much evaluation. Once the humidity sensor stabalized it tracked pretty well with other sensors I had. This was both for desert 20% level and more humid 50%. I did not have an exterior Honeywell sensor to try outside. I was also happy with the A/D when using a moisture sensor as an input. Similiar good results with DI and DO.

 

[FrankMc]

Hi Guys

Just thought i would mention that there,s now an xPL Plugin for the web control board...

http://www.doghouselabs.com/software/index...p=xPLWebControl

HTH
Frank

 

[RonX]

Is there a way with this board to check if voltage is going to a LED without interfering to the LED operation? How do I need to wire it? I'm planning to check the status of an APC surge protection device.

 

[FrankMc]

Make yourself an Led Probe....Consists of an LDR and a 741 op amp (and some resistors)...bit of googling should help...I designed my own led + video probe...see link...completey isolated from the led its monitoring...You just need to encapsulate the ldr in a housing and stick it over the led you need to monitor ..(hope that makes sense)....
http://www.hobby.armaghelectrical.com.au/page56.html

HTH
Frank

 

[fabriziojoe]

I just ordered one of the WebControl units from Amazon to monitor several IDF rooms.
Could someone point me in the right direction as far as temperature sensors and how to power them at the remote location?

Thanks!

 

[Michael McSharry]

I just ordered one of the WebControl units from Amazon to monitor several IDF rooms.
Could someone point me in the right direction as far as temperature sensors and how to power them at the remote location?

Thanks!

The ones I found that work with the Web Control are http://cgi.ebay.com/Digital-Thermal-probe-...=item35a7edfb6e

Power can be be from the WebControl directly for short distances. For long distances where the voltage drop is excessive then a stable source of a litle under 5VDC can be used.

The DS18B20 interface on the WebControl is its weak point. I would recommend the WebConrol for just about any local control application, but not a great unit just to interface temperature sensors.

 

[pete_c]

I bought one of these for one very small server room (combo MDF - 25X100) a couple of years ago on a shoestring budget.

It was cheap - utilized all the ports with sensors everywhere.

NTI

 

[tparvais]

Hello

Wat could be the advantages of the webcontroller board vs. HA7Net box ?

Thomas

 

[pete_c]

The self contained I/O possibilities are greater on the $35 Webcontroller and the $155.95 HA7Net box.

I'm impressed though with the HA7Net box and their new Thermocron server.

With some firmware "adjustments" the Webcontroller would be an every better "deal" at $35 than its higher priced competitors right now. Some improvements I would for now like to see (maybe providing the source code for the firmware to use at your own risk):

1 - the ability to utilize any 1-wire parasitic temp modules and "built" in power supplied multiple external power 1-wire humidity sensors.
2 - NTP fixes

An ultimate "do all" 1-wire box would provide (my wish list):

1 - Both RS-232 and ethernet connectivity (with some basic intelligence)
2 - be able to work with a wide range of 1-wire devices / multiple voltage / parasitic or non parasitic
3 - hub style (HB like) connectivity
4 - both star and daisy chain topology
5 - the weather (environmental) station box (wind, wind direction, rain, humidity, barometer, moisture sensor, temperature, lightning sensor, light sensor, etc sensors) - say like a new 1-wire sensor - what do you want to get from said sensor GUI.
6 - digital / analogue I/O
7 - an easy basic gui for rudimentary functions and an interface into some detailed modifications of OS.
8 - ability to store some data
This box would be worth $155 or even $200 or even $250 if it provided an "all in one" solution.

 

[fabriziojoe]

I just setup my new WebControl and cannot send emails.
I configured the appropriate output and setup my email server with the correct credentials.
Where am I going wrong?

Do I need to configure the following under the "Select Trigger Configuration" and if so what do I set it to?

Boolean Rule to set output TRUE max characters 32
Boolean Rule to set output FALSE max characters 32

Thanks

 

[tparvais]

Hello

If I understand well, the webcontrol is able to read only DS1820 ? And not any other Hobby-board sensors (hummidity, barometer, rain, wind....)

Thomas

 

[pete_c]

Yes and one humidity sensor.

 

[hult]

WebControl by CAI Networks is a $35 TCP/IP-based (web) device that I've used for about a year and can recommend... [snip]
.. I also tested various 1-wire temperature devices for them and based on that they added the more accurate DS18B20 1-wire device than the "econo" DS1822 device which was the only device they previously supported.

The DS18B20 looks to be sensitive to the input voltage when used in the simple interface mode that CAI is using. This means that one needs to be concerned about the voltage drop over the length of wire between the 5V source and the sensor. I have four different production lots of DS18B20's that I have tried. The most recent one I obtained on a recent ebay purchase does not work at all and I suspectg it is actually a -PAR device. I have one lot that tracks very nicely with other sensors that use a DS9097U interface in parasitic mode. I have two lots that produce unreliable results. Typically too high of a reading unless locally injected and then sometimes locks up when injected. I have tried both mods to increase the DQ midpoint and the Vdd and these did not make as much difference as changing the sensor. I suspect that a redesign to accomodate the parasitic power mode is not being planned by CAI so one's success will depend upon the DS18B20 they happen to have.

The ones I found that work with the Web Control are http://cgi.ebay.com/Digital-Thermal-probe-...=item35a7edfb6e

Power can be be from the WebControl directly for short distances. For long distances where the voltage drop is excessive then a stable source of a litle under 5VDC can be used.

The DS18B20 interface on the WebControl is its weak point. I would recommend the WebConrol for just about any local control application, but not a great unit just to interface temperature sensors.

Several observations and some planned actions:

1) As I understood it, the initial problem with migrating from the ' "econo" DS1822 device which was the only device they previously supported' to the more accurate DS18B20 was a timing issue. (More bits need to be received from the DS18B20 than frm the "econo" version). For this and other reasons I am sceptical of the problem being fundamentally a power-supply issue.

2) I initially tested the Webcontrol with a full array of DS18xxx devices obtained directly from www.Maxim-IC.com. Two individual DS18B20's worked with the new fimware. But (as several others have also) noted, it doesn't with the pile of DS18B20's I purchased at low prices from various eBay distributors.

Without claiming to have reached any conclusions, I would suggest folks read Maxim's discussion about the rampant problem of substandard, off-spec and counterfeit ICs here:

www.maxim-ic.com/sales/counterfeit_parts.cfm

I note that the only ebay-purchased DS18B20 device that Michael and others have found works (Is this assertion correct? Any one else have other observations/data?) is the "Digital-thermal probe" referenced above and that it is the only one on eBay that explicitly describes the provenance of the IC (" Maxim-made"). Make of that what you will ...

3) It seem likely (to me at least)that the sensitivity that others have found with cable length is not (barring outright component failure) primarily power-supply related, but timing related owing in part to the increase in capacitance with increasing cable length. This has long been a bug-a-boo with 1-wire devices, in part because timing and signal waveform strongly depend on transmitter design as well as load capacitance. Maxim has a discussion and a variety of fixes here and elsewhere.

http://www.maxim-ic.com/app-notes/index.mvp/id/4104
http://www.maxim-ic.com/app-notes/index.mvp/id/148

Quote: A proper match among network components (i.e., master, network cabling, and 1-Wire slave devices, "slaves") is the precondition for reliable 1-Wire operation. A 1-Wire network is a complex arrangement of 1-Wire devices, communication lines, and connections. Every 1-Wire network is different, often both in topology (layout) and hardware.

4) I've ordered a fresh batch of known-authentic DS18B20's and will scope the output pf these and known problematic eBay ICs to assess whether there is an obvious timing/rise-time signal error. I may also see whether an output buffer and/or RC filter helps as described in the second Maxim Ap Note cited above help.

( Why I continue spend time on fixing/dealing with 1-wire performance issues after a decade+ of grief is something that maybe only a shrink can explain ....)

HTH ... Marc