Master Slave configuration (control of multiple charging stations)

The cFos Power Brain Wallbox is able to control other EVSEes (also from other manufacturers) including load management. To do this, a cFos Power Brain Wallbox is designated as the master and the other EVSEes are connected to the master as slaves. Linking other EVSEs to a cFos Power Brain Wallbox is possible via WLAN (Modbus TCP/IP) or two-wire connection (Modbus RTU).

Why do I need this?

When using several EVSEs at the same time, the maximum possible grid connection power is often exceeded. This can save you the costs of upgrading your power connection. For single-family homes, the callable grid connection power is usually 14.5kW, if there is an electric water heating system, 34 kW.

What do I need for this?

• cFos Power Brain Wallbox and the cFos Charging Manager already included in the wallbox
• Supported second wallbox. List of supported wallboxes
• WLAN network (only for the master box, the slave wallboxes can be connected via Modbus RTU)
• One USB RS485 adapter (FTDI, virtual COM port) per Modbus RTU
  The cFos Power Brain Wallbox also has a Modbus proxy. If you have limited WLAN reception or do not want to connect all wallboxes to the network via WLAN, you can use Modbus RTU at these points instead. To do this, connect the wallboxes without WLAN coverage to a Power Brain wallbox via Modbus RTU and then set up the proxy. The master box then addresses all wallboxes via the cFos Power Brain as if they were connected via WLAN or Modbus TCP/IP.
• General material list

Configuration via WLAN with Modbus TCP/IP (recommended)

1. Register the cFos Power Brain Wallbox via WLAN. Commissioning the cFos Power Brain Wallbox
2. Register the slave EVSE via WLAN. Please use the manufacturer's instructions if the EVSE is not a cFos Power Brain Wallbox
3. Open the user interface of the master EVSE, Charging Manager settings. Activate the load management, enter the house connection power provided in your house connection under "Max. total power". Depending on how your EVSEs are supplied, you can still limit the maximum power of the EVSEs under "Max. total EVSE power". Save settings.
4. The cFos Master EVSE is already entered as an "Internal EVSE". Use the following parameters for the Master Box:
• Device type: cFos Power Brain
• ID: 1 (leave unchanged for Master)
• Optional: Attached (electricity) meter Electricity meter
5. Add the "slave" cFos Power Brain Wallbox to the settings. Use the following parameters for the slave box:

• Device type: cFos Power Brain
• Address: the corresponding address in the form IP address:port, example: 192.168.2.151:4701
• ID: 1 (for Modbus TCP/IP)
• Optional: Attached electricity meter
6. If you want to add more Slave Boxes, you can repeat this process until all Slave Boxes are connected.
7. The configuration is now complete and your boxes are controlled by an intelligent load management system. You can track the status of the EVSEs on the start page.

Configuration for two-wire connection with Modbus RTU

1. Set up the cFos Master EVSE and the Charging Manager as described above under Modbus/TCP
2. Ask your electrician to wire the slave EVSE with a twisted pair connection to the connection of the cFos Power Brain Controller, Modbus A to A, B to B as a bus.
3. Add the "Slave" cFos Power Brain Wallbox to the settings. Use the following parameters for the slave box:
   • Device type: cFos Power Brain
   • Address: COM port, for example: COM1,9600,8,n,1 (the COM parameters in the Charging Manager of the Master EVSE must match the parameters in the Slave EVSE.
   • ID: A unique ID must be assigned here for each EVSE (and, if applicable, for each meter added), e.g. for EVSEs 1,2,3,etc. for meters 20,21,22,etc.
   • Optional: Attached electricity meter
   • Open the user interface for the EVSE (e.g. by entering its IP address in the browser) and configure the following under "Slave/Standalone Settings": Charge enabled, Modbus enabled, the uniquely assigned Modbus slave ID and as TCP port / COM settings, the same settings as you have specified as the address for this EVSE in the master EVSE, e.g. COM1,9600,8,n,1.
4. If you want to add more slave boxes, you can repeat this process until all slave boxes are connected.
5. The configuration is now complete and your boxes are controlled by an intelligent load management system. cFos Charging Manager. You can track the status of the EVSEs on the start page.

Questions and hints

Is it possible to create a master-slave configuration completely without WLAN?
Yes. However, we do not recommend this due to the following disadvantages: An Internet connection is required for software updates (once the Master Slave configuration has been set up, it no longer requires an Internet connection to operate). Access to the Master Box without an Internet connection is only possible via the cFos Power Brain Wallbox's own access point. You must manually set the time in the Master Wallbox and update it if necessary.

What happens without load management and simultaneous charging of several wallboxes?
Without load management, the fuse could blow.

How do I find out the network address of my wallbox?
As soon as you have connected your cFos Power Brain Wallbox to your home network, you can read out the network address in the router menu.

Can I count the power consumption of each individual box?
Yes, you can use the supplied S0 meter or a Modbus energy meter. You can find a list of supported meters here.
Options for using the electricity meter. If you have added meters to the configuration of each wallbox as described above and these are attached to the wallbox, the cFos Charging Manager can determine the power consumption and the current power drawn by each wallbox and use it for load management. Without meters, the cFos Charging Manager assumes that the car always uses the maximum charging current allocated to the wallbox (static load management).

How many slave boxes can I connect?
A cFos Power Brain Master can manage up to 25 slave boxes.

What costs will I incur?
With a cFos Power Brain Wallbox, you can manage up to 3 third-party boxes and any number of cFos Power Brain Wallboxes using the Charging Manager. If you want to connect more than 3 third-party boxes as slave boxes, you will need additional licences. cFos Charging Manager