Master slave configuration (control of multiple charging stations)

The cFos EVSE is able to control other EVSEs (also from other manufacturers) including load management. For this purpose, one cFos EVSE is designated as the master and the other EVSEs are connected to the master as slaves. It is possible to link other EVSEs to a cFos EVSE using WLAN (Modbus TCP/IP) or a two-wire connection (Modbus RTU).

What do i need this for?

If several EVSEs are used at the same time, the maximum possible network connection power is often exceeded. This saves you the costs of upgrading your power connection. For single-family houses, the available mains connection power is usually 14.5 kW, and 34 kW if electrical hot water is available.

What do I need for this?

  • cFos Power Brain Wallbox and the cFos Charging Manager, which is already included in the EVSE
  • Second wallbox supported. List of supported wallboxes
  • WLAN network (only for the master box, the slave EVSEs 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 WiFi reception or do not want to connect all EVSEs with WiFi to the network, you can use Modbus RTU at these points instead. To do this, connect the EVSEs without WLAN coverage to a Power Brain Wallbox via Modbus RTU and then set up the proxy. The Masterbox then addresses all EVSE 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 of the cFos Power Brain Wallbox
  2. Register the slave wallbox via WLAN. Please use the manufacturer's instructions for this if it is not a cFos Power Brain Wallbox.
  3. Open the user interface of the Master Wallbox, 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 wallboxes are supplied, you can limit the maximum output of the wallboxes under "Max. Total wallbox output". Save settings.
  4. The cFos Power Brain Master Wallbox is already entered as an "Internal Wallbox". 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:
    6. Example slave wallbox
    • Device type: cFos Power Brain
    • Address: the corresponding address in the form of IP Address: Port, example: 192.168.2.151:4701
    • ID: 1 (with 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 wallboxes on the start page.

Configuration for two-wire connection with Modbus RTU

  1. Set up the cFos Power Brain Master Wallbox and the Charging Manager as described above under Modbus/TCP
  2. Ask your electrician to wire the slave wallbox with a twisted two-wire connection to the connection of the cFos Power Brain Controller, wire 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: Example Modbus
    • 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 wallbox must match the parameters in the slave wallbox.
    • ID: A unique ID must be assigned here for each wallbox (and, if applicable, for each added meter), e.g. for wallboxes 1, 2, 3, etc. for counters 20,21,22, etc.
    • Optional: Attached electricity meter
    • Open the user interface for the slave wallbox (e.g. by entering its IP address in the browser) and configure the following under "Slave/Standalone Settings": Load activated, Modbus activated, the uniquely assigned Modbus slave ID and as TCP Port / COM Settings, the same settings as you specified as the address for this slave wallbox in the master wallbox, 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 wallboxes on the start page.

Configuration of the slaves

You must set the charge management mode under "Settings" to "Monitoring" in all slaves. The same TCP ports or COM parameters and the same Modbus ID must be stored under the settings for the wallbox and meter as you have set in the master for the respective slave.

Questions and hints

Is it possible to create a master-slave configuration completely without WLAN?
Yes. However, we do not recommend this because of the following disadvantages: An internet connection is required for software updates (once the master / slave configuration has been set up, it no longer needs an internet connection to operate). The Master Box can only be accessed without an Internet connection via the cFos Power Brain Wallbox's own access point. You have to 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 the 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 for this. Here is a list of supported counters.
Ways to use the electricity meter. If you have added meters to the configuration for each wallbox, as described above, and these are attached to the wallbox, the cFos Charging Manager can determine the power consumption and the currently drawn power of each wallbox and use it for load management. Without a meter, the cFos Charging Manager assumes that the car will always use the charging current allocated to the wallbox to the maximum (static load management).

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

What will this cost me?
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 external boxes as slave boxes, you need additional licenses. cFos Charging Manager