Before you start
Before you begin, make sure:
The TQ Energy Manager EM 420 is physically installed and powered on
You have the serial number and device password (located on the identification plate)
If measuring currents above 63A, a current transformer is installed with:
Secondary current: 5A
Accuracy class 1 or better
Step-by-Step Instructions
1. Connect the meter to the network
Connect an Ethernet cable to either Ethernet port on the EM 420
Verify the connection is established by checking the LED indicators on the device
For network infrastructure requirements and troubleshooting, see Infrastructure requirements for the gateway.
2. Access the meter settings
Open a browser on your device
Navigate to the meter's web portal
Log in using the password on the identification plate of the device
3. Enable communication via Modbus
Navigate to
Modbus TCP slaveEnable Activate TCP slave
Save the settings
4. Configure current transformer factor (if applicable)
If the EM 420 is installed with current transformers for currents above 63A, configure the transformer ratio.
Navigate to
Device settingsEnable External current transformers
Set the current transformer factor according to your installed transformer ratio
Save the settings
5. Disable internal data logging
To avoid unnecessary storage usage, disable the internal data logger.
Navigate to
Home → Data store → AppEnsure the Data logging option is
deactivatedSave the settings
6. Discover the meter in the commissioning wizard
The meter is now ready for the commissioning wizard. The gateway will scan the network to find available devices, which may take a few minutes. Once complete, the TQ Energy Manager EM 420 will appear on the results page.
FAQ
Why isn't the meter appearing in the commissioning wizard?
Check that the Ethernet cable is connected and the network LEDs are active. Confirm that Modbus TCP slave mode is enabled under Modbus settings. Restart the gateway and wait for the network scan to complete.
How do I update the firmware of the meter?
Download the latest firmware from the TQ-Systems website and perform the update through the device web portal.
For detailed update instructions, refer to the official TQ-Systems documentation.
What current transformer specifications does the EM 420 require?
If using current transformers, the secondary side must be 5A and accuracy class 1 or better. For larger transformer ratios, use higher accuracy transformers — accuracy directly affects energy management performance.
Why should I disable the internal data logger?
The internal data logger stores measurement data on the device. Disabling it avoids unnecessary storage consumption and keeps the device resources available for real-time communication with the gateway.
Where do I find the device password?
The device password is on the identification plate attached to the EM 420 unit.
What if I cannot find or have lost the password?
Contact the TQ-Systems manufacturer support team. The password is device-specific and cannot be reset without manufacturer assistance.
Supported models
EM 410
EM 420