Posts made by pavel.cernocky

So the 1 wire stopped working again. I tried running the mbpoll command from Stefan, but it's not working.

Not sure whether the $ on the end of the line is some typo, it seems not valid, mbpoll complains about.

As I understand it, the command tries to set modbus coil 1001, which is named 'Enable/Disable 1Wire Bus' in Neuron documentation.
It seems the Mervis variable OW_off_1 is mapped to the same modbus coil, so turning it on/off should do the same thing. (UPDATE: confirmed by updating the variable in Mervis and watching by mbpoll)

Any other ideas?

OK, seems promising. I'll try it on next failure and will reply back.
Thanks a lot!

I have several temperature sensors connected via 1-wire to Neuron and occasionally all of them stops working. Sometimes they work for one day, sometimes for several months.

In Mervis in variables in debug mode I see Communication error True and the temperature is zero.

On the status screen I see:
Sent packets 2746181
Received packets 2441053
Wrong packets 4
Packet error ration 0.0%
Don't know why is the difference between sent/received packets that big and how it corresponds with wrong packets and error ratio.
(Wanted to paste image here, but it doesn't work)

I tried restarting Raspberry, but not sure whether it could help. Is the 1-wire bus connected directly to PLC or is it connected through Raspberry and then to PLC?

I also tried setting OW_off_1 to true and then back to false (as found elsewhere on the forum), but it didn't help. Is this switching to true and false the right approach?

The only thing which helps is powering off and on the whole Neuron and that's really not what I can use in practice.

I have shielded cables and serial topology, but it's possible there are some communication errors anyway. I think that the controller should be able to recover from that errors and not stuck forever.

I have found several posts in forum complaining about similar behavior, so it seems it's quite common problem.

Could you please guide me to some solution? Or is it necessary to make a fix on Unipi side?

Hi,
is there way to persist some variables through neuron restarts (power outages)?
There is a property "Write on change" on each variable, but I haven't found anything in doc and I'm not sure whether it could be useful.
Thanks.

@tomas_hora OK, I see, that makes sense.
Thanks a lot for your support.

@tomas_hora OK, I got it. I was only deploying solution, but didn't uploaded configuration. It's a bit misleading to have 2 "upload" options on two different places. What each of these actions exactly does?

Now I can see my data on https://db.unipi.technology/viewer, but it's strange, that there are missing points from one or other thermometer, only rarely there are both values at one time.

What can cause this behaviour?

@tomas_hora Runtime identifier is also set, should it be set to something specific or should it match something?
What about Trigger variable name in history properties, should it be filled? I haven't found any doc about this.
I'll check the system status as soon as I'll reach the PLC.

I've set up History like this:

And I have these variables in History:

MervisDB parameters:

If I debug the PLC I can see how the variables are stored in history. (Don't know why every 3 seconds, given that save period is one minute).

But I can't see anything on https://db.unipi.technology/viewer.
All I get is this message in bottom left:

If I enter wrong credentials, then I get different message, so credentials should be ok.

What I'm doing wrong?
Also, is there any way to debug it on Neuron side? Eg. to see whether it is sending some data at all? I've tried "Download system log" in Mervis, but there is no mention about success or failure.

Thank you.

@tomas_hora OK, thanks for hints.

What do you mean by "similar solution"?
If it's not priority, what's preferred way to connect multiple thermometers to Neuron?
Thank you.

Hi,
will there be any 1-wire extension module for Neuron?
I mean something like "8channel 1Wire" https://www.unipi.technology/cs/8channel-1wire-rozsireni-p47?categoryId=14
Thanks,
Pavel

OK, thanks for the answer, now it makes more sense :-)
The link you sent explains a lot. Maybe you could add it to your wiki.
So the key point is, that your hub is replacing star topology with linear topology, which should be better for 1-wire network.

Thanks for reply and clarification.

1. I'll try it on one channel and I'll see
3. The wiki states:

... we are not trying to connect as many 1Wire devices as possible but to have maximum reliability. To achieve this we are trying to minimize the length of DQ line between the end point and the 1Wire bus. So we are using not 1Wire but rather 2Wire topology.
This means that at the end device you have to connect the DQ line to both 6 and 7 pins of the RJ45 connector in order not to split the topology.

And that's what I don't understand.. How do you minimize the length of DQ line with 2-wire topology, how does the topology look like? What's the point of connecting booth pins 6 and 7 to DQ?

4. Thanks for clarification

Hi, I would like to connect 20 temperature sensors via 1-wire bus. Wiring to sensors is shielded STP with length from 4 to 25 meters in star topology.

1. Do I need some expansion module (8channel 1Wire expander?) or is the Neuron 1-wire port sufficient?
2. What's the limitation of cable length/number of sensors?
3. Is somewhere described how your 2-wire topology works (I found only this http://unipi.technology/wiki/1Wire_topology) compared to classical 1-wire bus as shown here http://www.jon00.me.uk/images/1wirebus.gif.
4. Why does the 1-wire Neuron connector has two DQ pins? Pin 6: Data (DQ) transmission, pin 7: Data (DQ) reception