Accurate, Local Home Energy Monitoring: Part 2 – Network Config

This entry is part 2 of 5 in the series Home Energy Monitoring

This post continues from the previous post in the series where I walked through the decision process on what energy monitor system to use and how to install Brultech GEM Monitor. I ended with the hardware physically installed and all Current Transformers (CTs) connected.

In this post, I continue from that point and walk through the network and software configuration defining each circuit size.

Network Configuration

First, connect the device to the network (I’m using Ethernet) and ensure it’s turned on. Then discover the IP address of the monitor. I found it by logging in to the router’s config web page and checking for the DHCP lease from the device. Brultech has a few different tools that help you discover the device, but they didn’t really work for me and looked like they were written a decade ago.

To configure how to control the device, I port scanned it and found it listens on several different ports:

23/tcp   open  telnet?
80/tcp   open  http
1025/tcp open  NFS-or-IIS?
8000/tcp open  http-alt    GEM ver1

Port 80 and port 8000 are both HTTP services that control different aspects of the monitor.

The default credentials for port 80 are username:admin and password:admin.

Disabling Wi-Fi

This GEM monitor includes both Wi-Fi and Ethernet connections. By default, it broadcasts a Wi-Fi network (SSID: GreenEye_XYZ) that you can connect to, however if you’re connecting via Ethernet, an extra Wi-Fi network just adds noise to the RF channel. Removing the antenna doesn’t fully stop it. Luckily in COM firmware version v4.17+, you can explicitly disable it (reference.) To disable it, navigate to:


and click the “Adv” tab at the top., then scroll down to near the bottom where it has a button for “AP off”

The GEM monitor should reboot and the Wi-Fi network will be gone. The first time I did this, the monitor failed to come back (possibly because I modified Wi-Fi settings on the port 80 before trying to disable it.) If that happens, reset it by holding the network reset button for 5 seconds and going directly to this page and disabling the AP.

Configuring the CTs

Since CTs can come in different sizes (30amps all the way to 200 amps,) the GEM device needs to know exactly what CT is installed on each channel. Otherwise it won’t know how to translate the signals it receives into the correct current measurement.

To assign the channels, download the GEM Network Utility from BrulTech download page. Switch to TCP Client mode, set Port: 8000, and enter the IP address of the device, then click Open on the right side.

If it succeeds, it should show Status: Connected. In the menu bar, click CT and PT Settings. In the window that opens, configure the CT types for each channel then click Save.

After that, check out the Live Data tab to verify everything looks right. Below, we tested turning on several heaters and verified that the values of each channel sum up approximately to the total in channel 1. Before changing the models in the previous steps, the channels were not adding up. After the change, I saw that the individual values didn’t sum up to be exactly equal to the total in channel 1, but it was pretty close and I imagine there’s some measurement tolerances because each channel is being measured independently.

GEM Utility showing lots of energy usage from several different devices confirming that it works.

Next Steps

Now everything should be measured correctly. The next step will be to connect it to HomeAssistant. This will come in the next blog post.

Series Navigation<< Accurate, Local Home Energy Monitoring: Part 1 – HardwareAccurate, Local Home Energy Monitoring: Part 3 – Software Config >>

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