Master-Slave Setup

Most public Charging Stations have two connectors.
Building a double Charging Station powered by Bender Charge Controllers requires two Charge Controllers per Charging Station (one for each connector).

The Master-Slave feature allows you to form an interconnected unit out of 2 Charge Controllers within a chassis, that acts as a single Charging Station when interfacing with EV drivers and external systems, such as Backends.
One of the two Charge Controllers will be the Master Charge Controller.

The Master is in charge of most control functions and will serve as the sole interface to the outside world.
To achieve a harmonious system the two Charge Controllers need to be configured to be a Master Charge Controller, and a Slave Charge Controller respectively.

1. Requirements

Make sure that

• Both Charge Controllers have the same controller firmware version. (Check the number at the top right of the Config UI)
• Both Charge Controllers have the Config UI set as the default. See here.

2. Configuration

Step 1: Configuring the Master

1. Connect the Charge Controller that should be the Master to a computer with a micro USB cable through the CONFIG USB port.
2. Log in to the Legacy Config UI using the Manufacturer Login Credentials
3. Under Manufacturer (http://192.168.123.123/legacy/manufacturer/manufacturer), set Master/Slave Mode to Master (the setting can be found near the bottom of the page)
4. At the bottom of the Legacy Config UI, click to apply the changes

Step 2: Configuring the Slave

1. Connect the Charge Controller that should be the Slave to a computer with a micro USB cable through the CONFIG USB port.
2. Log in to the Legacy Config UI using the Manufacturer Login Credentials
3. Under Manufacturer (http://192.168.123.123/legacy/manufacturer/manufacturer), set Master/Slave Mode to Slave (the setting can be found near the bottom of the page)
4. At the bottom of the Legacy Config UI, click to apply the changes

Step 3: Wiring

1. Run a USB cable from the Master Charge Controller's CONFIG USB port to one of the Slave Charge Controller's USB host ports

tip

This is also how an installer would from now on connect to the charging station to access the configuration interface.

2. Run a USB cable from the Slave Charge Controller's CONFIG USB port to your computer

Step 4: Accessing

	Master Charge Controller	Slave Charge Controller
Config UI	http://192.168.123.123:81	http://192.168.123.123
Legacy Config UI	http://192.168.123.123:81/legacy	http://192.168.123.123:82/legacy
Legacy Config UI (manufacturer)	http://192.168.123.123:81/legacy/manufacturer/manufacturer	http://192.168.123.123:82/legacy/manufacturer/manufacturer
SSH	192.168.123.123:23	192.168.123.123:22

3. Accessing the Master and Slave Controllers

Access the Slave and Master Charge Controller like so from now on:

Master Controller	Slave Controller
http://192.168.123.123:81	http://192.168.123.123

4. Port Forwarding Limitations in Master-Slave Setups

In Master-Slave setups, the Slave connects to the Master via an internal, non-routed network. While some ports are forwarded to the Master's network interface, the Slave cannot access other devices on the Master's external network.

This means, for example, that the Slave cannot communicate with Modbus TCP meters connected to the Master’s network. As a result, the Slave cannot use Modbus TCP meters as primary meters.

4.1. When to use Single Feed mode

Single Feed mode applies when a Double Charging Station (e.g. 2×22 kW) is connected using a single supply line that cannot provide the full combined power for both connectors. For example, if the line is rated for only 22 kW:

• A single EV can charge at the full 22 kW when the second point is idle.
• When both connectors are in use, power is shared (e.g. 2×11 kW).

In setups like this, enabling Single Feed is required. Without it, the system assumes each connector has access to full power at all times, which can result in:

• Overloading the supply line, and
• Incorrect application of current limits

4.2. Enabling Single Feed mode

If the Double Charging Station is equipped with a single feed, set the following setting on both the Master Charge Controller and Slave Charge Controller:

1. Log in to the Legacy Config UI using the Manufacturer Login Credentials
2. Under Manufacturer set Charging Station with single feed to On (the setting can be found near the bottom of the page)
3. At the bottom of the Legacy Config UI, click to apply the changes
4. Repeat this for the second Charge Controller of the Double Charging Station

The Double Charging Station will now share the available current Charging Station Installation Current Limit [A] between Master and Slave equally as soon as both are connected to an EV.