Hi,

 I've got some temp sensors that are not registering at the brick.  The wiring is a single bus wire, and in both instances there is currently only one sensor on the wire. I've tested the connection and can see 5v on both blue and brown pairs.

However, when I issue the RT command, or cycle the bricks nothing is happening. Any suggestions ?

thanks

 Paul

UPDATE: I can see a small pulse accross the 5v and data line making me think that sensor is active, however when I try accross one I have working locally the pulse appears to be in the other direction. [Note I only have an analogue meter so not able to get any absolute readings]

Any ideas welcome - at the moment I have wire hanging out of ceilings that I need to wire up, but want to ensure I've got my connections right first. 

 

I've now got a digital meter, and can see the 5v line registering @ ~ 4.96v, but the data line back at the brick is varying between the 4.3 & 4.6. Is there any particular tolerences that I'm overstepping? The RT command isn't pickup this sensor Thanks Paul

The data line is held up to 5V and pulled low to send data. What you will see is a periodic drop in the data voltage when communication is attempted.

Communication starts with a long 0V pulse to reset the sensors and is then followed by the sensors sending a presence signal. If the sensor is duff then there will be no presense detect and the webbrick will not do any more. Sounds like a duff sensor.
 

Hi

I have seen that if I have temp sensors running in a serial run, if I connect one at the end of the line then it seems to pick up, but when I connect one in-line using one of these http://cpc.farnell.com/jsp/search/productdetail.jsp?SKU=CN04645 and punching the connectors for temp sensor and RJ45.

 How do others connect these in-serial temp sensors, it could be the connector quality, but can anyone advise on the connectors that work well, for this and general RJ45 connections

Thanks

 Paul

It would appear that the problem here is that you are connecting them in-line. Even though it is a one wire data bus, a bus network setup does not work. Each sensor requires a separate route back to the webbrick in a star network style. You could share the 5v supply and Ground then use a different colour for each of the data signals. Hope this helps.

Thanks for the response, but that seems to differ from the posting Andy made here http://community.webbricksystems.com/forums/p/222/588.aspx#588 . The maximum number of sensors on a run I have is 5, but for the Dallas sensors on the T1 input, they can connect 5 sensors in a bus design (so I believe). Any suggestions will help.

 Thanks

Paul

 Paul

   They should be wired in a bus network.

Richard

  The returns should be on the orange pair so that bus integrity is maintained (i.e. you use bus wiring but star cabling).

 Regards

 

Andy