Scalextric Sport Digital Console

C7042 RS485 Interface

In the spirit of openness, and to encourage 3rd party development of software that interacts with the C7042 powerbase, Hornby Hobbies Ltd have agreed to make the C7042 interface documentation generally available.

Please be aware that Hornby Hobbies will not support the use of this interface, nor will they endorse any of the subsequntly developed 3rd party products. So feel free to download and make use of the documentation, but also understand that you will be operating on your own. If you are not familiar with both software and hardware components of a RS485 interface, you are well advised to make use of existing products to achieve your objectives.

With all of that said, the documentation is available here.

Amendments to the C7042 SNC protocol

Firmware version 0.82 (and all subsequent versions) introduced an additional byte to the incoming packet identifying if a button had been pressed on the powerbase. This additional byte extends the incoming packet to 15 bytes, with the button status byte at byte 14 (after the timer and before the CRC check). The button status bits are set as follows:

Firmware version 1.05 (and all subsequent versions) introduced the support the transmission of AUX data, which can be used by the InCar-Pro decoder. This AUX data takes the form of a single byte for each car, and so the overall packet length remains the same as normal.

In order for the powerbase to recognise that the incoming data is AUX data, the operation (first) byte is adjusted as follows:

Each car byte in the AUX data takes the following format:

MS Bit1 bitLights on/off
1 bitSP on/off
1 bitRC1 on/off
5 bitsreserved, must be $1F

The C7042 powerbase will retain the last transmitted AUX data and send it out on the track every 30 packets. As a result, there is no need to transmit AUX data over SNC unless it requires changing. The C7042 powerbase will also respond to an AUX packet transmission in the same way as it would to a normal DRIVE packet.

Additional information regarding the InCar-Pro firmware is available at ElectricImages.

Firmware version 1.07 (and all subsequent versions) introduced the ability to ID cars and control powerbase settings. This is achieved in the following ways:

To ID a car you send a standard drive packet (operation byte, bit 6 set) and then make use of the LED status byte in the following way:

To set powerbase settings you send a standard AUX packet (operation byte, bit 6 unset) and then make use of the LED status byte in the following way: