Splitting the RJ11/P1 cable

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Splitting the RJ11/P1 cable

Postby Plantje » Wed Oct 26, 2016 7:21 am

Ever since Eneco had such issues with their Service Center I want to bypass the Toon and the Service Center in getting the metering data into Domoticz. Still I want to use both. So I want to put an old tablet near the meters and attach a cable directly from the smart meter to my tablet running Domoticz.

Now, I understood it is not safe to just split the RJ11 cable and attach the Toon meteradapter to one end and a RJ11 to USB cable into the tablet on the other end of the splitter. How can I connect both the USB cable and the Toon meteradapter to my P1 connector in a safe way?
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Re: Splitting the RJ11/P1 cable

Postby hvxl » Fri Oct 28, 2016 2:32 pm

I suspect the part that is considered unsafe is for two devices to drive the request line. Connecting any two outputs together can lead to excessive currents. So, just make sure that only one device drives the request line. You can do that by only connecting the request line to one device, or by adding diodes to the request output of each device.

I originally had a device hooked up to my smart meter that got its power from the 5V provided on the P1 connector. The device connected pins 1&2 together as well as pins 3&6. When I went to hook up the toon, I simply used an ISDN splitter that only contains 4 of the 6 pins. That way the +5V from the smart meter doesn't make it to my device anymore. Instead the toon meteradapter now drives the request line and also powers my device. This setup has worked like charm for almost a year now.
Schelte
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Re: Splitting the RJ11/P1 cable

Postby Plantje » Tue Nov 01, 2016 11:45 am

Thank you for responding! I hadn't seen it yet, because for some reason all contributions here must be approved...

So, it is current that may be the issue...not voltage. Sounds logical. In the meantime I have figured out what that request line is and I think I will be good there.
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Re: Splitting the RJ11/P1 cable

Postby marcelr » Tue Nov 01, 2016 10:36 pm

I simply use an RJ11 splitter from the DIY-store to connect two devices to my P1 port. Has been working for the last four years, never had any issues.

best,

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Re: Splitting the RJ11/P1 cable

Postby eDsuB » Fri Nov 17, 2017 4:58 pm

Best is to cust the 5V line in one of the two, otherwise you are connecting two powersources of 5V. You might be lucky, but you also might be unlucky.....
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Re: Splitting the RJ11/P1 cable

Postby Plantje » Fri Nov 17, 2017 9:57 pm

That's what I did. I cut one of the 5V lines, but it was not very easy to find.
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