OW Problem

[stevendt]

Hi,

I have a problem connecting an additional temperature probe to my OW network and would appreciate some help please . . . .

I have 6 channel hub connected to a few temp/hum probes as follows :-

PC ----> DS18S20 ----> 6 Ch Hub

Hub Ch1 DS18B20
Hub Ch2 HB Hum Sensor (no temp probe on board) with another DS18B20 connected to the screw terminals
Hub Ch3 unused
----------------

I'm trying to add another DS18B20 to the out port of the humidity sensor box. When I do this, I can't read the network anymore and the new temperature probe overheats and burns out. I **think** that the wiring is OK - I can read the new probe "stand-alone".

Does this sound like a cable problem or have I got some jumpers wrong ?
I am using the default jumper settings supplied with the Hub and hum sensors.

Any help would be really appreciated,
Regards
Dave

 

[sda]

"with another DS18B20 connected to the screw terminals"

The screw terminals, according to the schematic, are data, gnd, +12v.

I assume you're using a ds18b20 in the to-92 (transistor type) package.
Are you connecting all 3 pins of the ds18b20 to the screw terminals?
If so, you're putting 12v into it.

If not, give detailed info about the cabling and connections.

 

[stevendt]

"with another DS18B20 connected to the screw terminals"

The screw terminals, according to the schematic, are data, gnd, +12v.

I assume you're using a ds18b20 in the to-92 (transistor type) package.
Are you connecting all 3 pins of the ds18b20 to the screw terminals?
If so, you're putting 12v into it.

If not, give detailed info about the cabling and connections.

Thanks for the reply, I don't think that this the problem though, the probe wired to the screw terminals of the humidity sensors appears to work fine. It's when another temp sensor is connected via cat5 on another HB temperature probe that has the problem. This one also has another probe wired to the screw terminals, I can't see why one would work fine (on the hum board) and one wouldn't (on a temp only board) unless the hum jumper has something to do with it ?

regards
Dave

 

[stevendt]

"with another DS18B20 connected to the screw terminals"

The screw terminals, according to the schematic, are data, gnd, +12v.

I assume you're using a ds18b20 in the to-92 (transistor type) package.
Are you connecting all 3 pins of the ds18b20 to the screw terminals?
If so, you're putting 12v into it.

If not, give detailed info about the cabling and connections.

Thanks for the reply, I don't think that this the problem though, the probe wired to the screw terminals of the humidity sensors appears to work fine. It's when another temp sensor is connected via cat5 on another HB temperature probe that has the problem. This one also has another probe wired to the screw terminals, I can't see why one would work fine (on the hum board) and one wouldn't (on a temp only board) unless the hum jumper has something to do with it ?

regards
Dave

Hi Again,

Apologies, I've looked at the schematics for the Temp/Hum board and hub and can see that you are correct. I can see that I have connected the unregulated hub voltage to VDD input via the screw terminals. When I get home at the weekend I'll try disconnecting the third wire from my end temp/hum board and see if the two DS18B20's can be read without frying one of the sensors !

What I still don't understand though is why I haven't fried another temperature sensor connected this way on the temp/hum board which has a humidity sensor fitted, no on board temperature sensor is installed and a DS18B20 is connected to all three screw terminals in the same way as one the problem board ?

regards
Dave

 

[ericvic]

Hi Again,

Apologies, I've looked at the schematics for the Temp/Hum board and hub and can see that you are correct. I can see that I have connected the unregulated hub voltage to VDD input via the screw terminals. When I get home at the weekend I'll try disconnecting the third wire from my end temp/hum board and see if the two DS18B20's can be read without frying one of the sensors !

What I still don't understand though is why I haven't fried another temperature sensor connected this way on the temp/hum board which has a humidity sensor fitted, no on board temperature sensor is installed and a DS18B20 is connected to all three screw terminals in the same way as one the problem board ?

regards
Dave

I don't see how that is working unless for some reason there is no unregulated voltage being supplied to the RJ45 jacks.

Eric

 

[stevendt]

Hi Again,

Apologies, I've looked at the schematics for the Temp/Hum board and hub and can see that you are correct. I can see that I have connected the unregulated hub voltage to VDD input via the screw terminals. When I get home at the weekend I'll try disconnecting the third wire from my end temp/hum board and see if the two DS18B20's can be read without frying one of the sensors !

What I still don't understand though is why I haven't fried another temperature sensor connected this way on the temp/hum board which has a humidity sensor fitted, no on board temperature sensor is installed and a DS18B20 is connected to all three screw terminals in the same way as one the problem board ?

regards
Dave

I don't see how that is working unless for some reason there is no unregulated voltage being supplied to the RJ45 jacks.

Eric

Hi Eric,

thanks for the comment. Now that I **think** that I see what I've done, then I don't know why it's working either !

You probably don't recall, but you supplied me a temp/humidity pre-built unit with no temp sensor fitted. My plan is to eventually solder a DS18B20 on the board but at the moment, the space is blank and I have cconnected a remote temperature probe to the screw terminals.

Even though I see now that I should not have connected the VDD wire to the 12v terminal, it does work ! The hub is powered by the PSU that you supplied and I have not altered the default hub jumpers or hum board jumper. I assume that the unregulated voltage is required for the hum sensor to work ? GIven that the unregulated voltage seems to be getting to the last device, then it must be going through the previous one in the chain too.

I connected the additional temp board to the outlet jack on the hum module with the results described above, i.e., the last device is not working (as expected I guess), but the previous (humidity0 one is.

Very strange ! Anyway, at the weekend I'll disconnect the wires from the 12v terminal on both and hope that cures the problem.

Regards
Dave

 

[stevendt]

I don't see how that is working unless for some reason there is no unregulated voltage being supplied to the RJ45 jacks.

Eric
[/quote]

Hi Eric,

thanks for the comment. Now that I **think** that I see what I've done, then I don't know why it's working either !

You probably don't recall, but you supplied me a temp/humidity pre-built unit with no temp sensor fitted. My plan is to eventually solder a DS18B20 on the board but at the moment, the space is blank and I have cconnected a remote temperature probe to the screw terminals.

Even though I see now that I should not have connected the VDD wire to the 12v terminal, it does work ! The hub is powered by the PSU that you supplied and I have not altered the default hub jumpers or hum board jumper. I assume that the unregulated voltage is required for the hum sensor to work ? GIven that the unregulated voltage seems to be getting to the last device, then it must be going through the previous one in the chain too.

I connected the additional temp board to the outlet jack on the hum module with the results described above, i.e., the last device is not working (as expected I guess), but the previous (humidity0 one is.

Very strange ! Anyway, at the weekend I'll disconnect the wires from the 12v terminal on both and hope that cures the problem.

Regards
Dave
[/quote]


OK - I'm an idiot !

The unregulated voltage on the VDD pin was the problem. On the one that I thought was working connected up the same way, the VDD connection was broken - how lucky was that !

Thanks for the help folks
Dave