How do I use the RJ45_Multi_Breakout board?

I’m trying to connect two DS18B20 temperature sensors to an EmonTx V3.4 using a RJ45_Multi_Breakout boad. The Tx is running the standard Discrete Sampling SW v. 2.3

If I connect just one DS18 sensor I have no problem and get good data.

When I try to connect two DS18 sensors using the RJ45_Multi_Breakout board the Tx does not find any temperature sensors. My hook-up is to plug in the two sensors and run a LAN cable from the board to the Tx.

What am I doing wrong? Do I need to use a different type og RS45 cable. Thanks in advance :slight_smile:

It sounds like you are doing everything correct. Please double check the Ethernet cable you are using to connect to the emonTx is not a crossover cable, just a standard ‘patch’ cable.

See photo (emonPi is shown but same works for emonTx V3.4):

Ah, think I have a different breakout board:

Will have a lookat the cable.

Planning to add a hard wire pulse sensor to the screw terminals. Is it correct that the latest Tx already have a pull down resistor?

Your board should work the same as the one in the photo, it just has less inputs :slight_smile:

Pulse sensor and one DS18 works a treat; Add a second DS18 and a little coding and I’m ready to monitor our district heating unit :slight_smile:

I tried two different types of RJ45 cables from the breakout board to the Tx, but the Tx refuses to find any temperature sensors when booting.

Going to make myself a new RJ45 cable. I assume the correct RJ45 cable is of the “straight through” type, i.e. all pins are connected to the same pin in the other end?

Does it matter to which port I connect the board to Tx cable to?

Although the RJ45 connector and Cat5 cable is used, it is not actually an Ethernet connection, so the answer is ‘straight through’. Only 3 wires need be used, gnd, power and data, of which gnd & data are ideally a twisted pair.

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Just tested, I can confirm a standard patch Ethernet cable works fine to connect multiple temperature sensors to the emonTx:

Thank you for the five-star support, impressive! :slight_smile:

Did a fresh “straight through” cable, and everything now works seamlessly. Got to do a little programming to get the MW and m3 heated water consumption, but that should not be too hard.

Next project will be to do a weight and temperature monitor for one or more of our bee hives, hope the RF radio can reach the base station from there.


Excellent! Your welcome. Nice work.

Ah very interesting, a side project is mine is bee hive temperature monitoring with my dad who’s a keen bee keeper. We’ve had a temperature monitoring system up and running for a few years now posting to Emoncms:

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