How do I use the RJ45_Multi_Breakout board?

Getting Started
1

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:

2

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):

IMG_5193__36054.1424864401.1280.1280.JPG1280×668 136 KB

3

Ah, think I have a different breakout board:

https://shop.openenergymonitor.com/rj45-expander-for-ds18b20-pulse-sensors/

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?

4

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

5

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?

6

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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7

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

2016-06-14 13.40.48.jpg703×800 161 KB

8

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.

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9

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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