The SPEEDBOX can output a variety of CAN messages, using Race Technology’s CAN data
message format. The rate at which each message is output is configurable, at up to 200Hz for
inertial-based messages, such as accelerations, combined speed and all INS measurements, and at up to 20Hz for
GPS-based messages. Additionally, there is a trigger timestamp message, which is output in
response to detected trigger events, and can be either enabled or disabled. Until GPS lock is
achieved, all GPS-based messages are output at only 1Hz, and are output at the full
configured rates once GPS lock has been obtained, and thereafter even if GPS lock is lost.
A detailed description of the Race Technology CAN data format, including the message
contents and the default addressing scheme, can be found on the knowledge base on the Race Technology web site here. A CANdb (.dbc) file is
available to aid message decoding, and can be downloaded from our website here. If the CAN addresses are changed from the default
settings, the supplied CANdb file will no longer decode the messages. The SPEEDBOX
supports both 11 and 29bit addressing, Bitrates are configurable to 125kbps, 250kbps,
500kbps or 1mbps.
In the case of the CAN output, the latency depends on both the presence of other traffic on the
CAN network, the bit rate that has been selected, and how many CAN messages have been
configured for output, and at what rate. This means that it cannot be considered deterministic.
The SPEEDBOX will output queued inertial messages before queued GPS messages, in order
to minimise the latency of the inertial messages. The remaining CAN messages, outputting
the GPS data, typically have a latency of between 50 to 100ms after the point to which the
data refers. The messages may be aligned with the GPS time to which they pertain with
reference to the GPS time field in CAN message RT_GPS_Time, if that message has been
configured for output.
A list of the available CAN messages from the SPEEDBOX is shown below. Note that for the SPEEDBOX-INS it is possible to output either the INS measurement or the raw GPS measurement for many of the parameters (e.g. position) so it is important to select the correct message for your requirement.