This article describes how to connect the reev EMS to a higher-level energy management system (external EMS). You will learn which network requirements apply and how to set up communication via Modbus TCP.
Prerequisites
Before you begin with the connection, make sure the following prerequisites are met:
A Teltonika router is installed on-site and operational.
A direct LAN connection between the Teltonika router and the external EMS is in place.
The external EMS is configured for data transmission via Modbus TCP.
Note: In this setup, no separate energy meter is required. The reev EMS controls the available power for the charging infrastructure solely based on the power values transmitted by the external EMS.
How It Works
The external EMS transmits the currently available current value (A) or power (kW/W) at the grid connection point via Modbus TCP to the reev EMS. The reev EMS receives this value and controls the connected charging stations accordingly.
Note: The Teltonika router is mandatory. It acts as an IoT gateway: it receives the Modbus registers from the external EMS and securely transmits the data to the reev EMS backend.
Step-by-Step Guide: Establishing the Network Connection
There are two options for connecting the external EMS to the Teltonika router. Follow the steps for the applicable option:
Option 1: Direct Connection
Connect the external EMS directly to the LAN port of the Teltonika router using a LAN cable.
Make sure both devices are on the same network.
Option 2: Connection via a Network Switch
Connect the LAN port of the Teltonika router to the network switch.
Make sure the external EMS is connected to the same switch.
Verify that both devices are on the same network (LAN).
Configuration of the External EMS
The external EMS must be properly programmed for communication via Modbus TCP. Ensure the following:
The external EMS sends the power limit at least every 5 seconds.
The Modbus TCP registers are configured according to the external EMS manufacturer's specifications.
The transmitted value corresponds to the available current (A) or available power (kW/W) at the grid connection point for the charging infrastructure.
Tip: Check the manufacturer documentation of your external EMS for the correct configuration of the Modbus TCP registers and the transmission interval.
Troubleshooting
Problem | Possible Cause | Solution |
No communication between external EMS and reev EMS | Devices are not on the same network | Check the LAN connection and network configuration |
Power values are not received | Modbus TCP registers of the external EMS not correctly configured | Check register configuration according to manufacturer specifications |
Charging stations respond with delay | Transmission interval of the external EMS too long | Ensure the power limit is sent at least every 5 seconds |
No data transmission to the backend | Teltonika router offline or not correctly configured | Check router connection and internet connection |
Frequently Asked Questions
Is a separate energy meter required?
No. When connecting to an external EMS, no separate energy meter is required. The reev EMS uses exclusively the power values transmitted by the external EMS.
Which protocols are supported for communication?
Communication between the external EMS and the reev EMS takes place via Modbus TCP.
Is the Teltonika router mandatory?
Yes. The Teltonika router is always required, as it acts as an IoT gateway that receives the Modbus data from the external EMS and transmits it to the reev EMS backend.
How often must the external EMS send the power value?
The power limit must be sent at least every 5 seconds to ensure reliable control of the charging stations.
Can the reev EMS also control the external EMS?
No. The communication is unidirectional. The external EMS sends the available power value to the reev EMS. Control of the external EMS by the reev EMS is not supported.