Wiring options

In the following we show you the cabling options for several EVSEs on our cFos Charging Manager. The cFos Charging Manager is integrated in our cFos EVSE and is available as a standalone version for a one-time fee per charging point. You can then run this on a Raspberry Pi or Windows PC.
If you let the cFos Charging Manager control your boxes, you have the following advantages:

  • Intelligent load management:
    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.
  • Solar excess charging:
    With the cFos Charging Manager and a solar system, you can ensure that your car is only charged when there is excess solar power available. Surplus = generation minus house consumption
  • Compatibility with a large number of supported wall boxes:
    Retrofitting load management and solar surplus charging on your existing wall boxes. These functions are usually only reserved for high-priced wall boxes
  • Terminating resistor 120 Ohm, 1/4W
  • Everything at a glance: monitor and control electricity meters, wall boxes and solar systems with one software

If you want to set up a charging park with more devices, you can use a mix of Modbus TCP/IP (WLAN), Modbus RTU (cable connection) and Modbus proxy without it (see below). Graphic cabling options

Modbus RTU connection

Important: We urgently recommend a twisted two-wire connection for the Modbus RTU connection. Telephone lines and any type of network cable are sufficient for this purpose.

  • Modbus cabling
  • <-> RS485 adapter (FTDI, virtual COM port) per Modbus RTU. You can operate approx. 20 devices on one bus.
  • USB isolator
  • Terminating resistor 120 Ohm, 1/4W
  • Network switches
  • Our optional Modbus kit contains everything you need for cabling

The maximum number of Modbus devices on one cable should not exceed approx. 20. After that, the cycle time increases because the cFos Charging Manager can only query all devices one after the other per bus.

Modbus proxy connection

Our cFos EVSEs support a Modbus proxy. Up to 20 Modbus devices are connected via Modbus RTU (cable) to a cFos EVSE or to a Modbus adapter on the Windows PC or Raspberry Pi. In this case, the Charging Manager communicates with all devices using the Modbus TCP/IP protocol. The proxy then forwards the Modbus requests to the Modbus RTU 2-wire connection.
This feature is particularly helpful for large systems or if you do not want to set up extensive WLAN coverage for your charging infrastructure.

Modbus TCP/IP connection (WLAN)

There are several options for achieving sufficient WiFi network coverage:

  • WLAN repeater: repeat the WLAN signal and must be expanded seamlessly.
  • DLAN: Internet over the power line. The WLAN signal is then sent from a socket near the EVSE.
  • WLAN access points: The access point is connected to the existing network via a network cable. End devices then dial into the access point via WLAN.