TEMES 1.0

The fast sample rate should not be slower than 10 ms (due to the timestamp synchronization).

 

The CAN messages are sampled during the fast recording cycle. Four CAN messages are buffered. A fast sample frequency of 10 kHz (= sample rate of 0.1 ms) should allow the recording of all CAN messages of a fully loaded CAN at 1 Mbit/s (assuming that both the CPU and the USB stick access is fast enough). If there are no 0-data-byte-messages, then the sample frequency can also be reduced to 5 kHz (= sample rate of 0.2 ms). If additionally the CAN bit rate is 500 kbit/s, then the sample frequency can be reduced to 2.5 kHz (= sample rate of 0.4 ms). If additionally the CAN messages are with 8 data bytes only, then the sample frequency can be reduced to 1.2 kHz (= sample rate of 0.8 ms).

 

CAN message size ≥ 47 bits (for any CAN message)

CAN message size ≥ 55 bits (for CAN messages with at least 1 data byte)

CAN message size ≥ 111 bits (for CAN messages with 8 data bytes only)

 

For maximal CAN bit rate of 1 Mbit/s:

fCAN message < 22 kHz (for any CAN message)

fCAN message < 19 kHz (for CAN messages with at least 1 data byte)

fCAN message < 9.1 kHz (for CAN messages with 8 data bytes only)

 

For CAN bit rate of 500 kbit/s:

fCAN message < 11 kHz (for any CAN message)

fCAN message < 9.1 kHz (for CAN messages with at least 1 data byte)

fCAN message < 4.6 kHz (for CAN messages with 8 data bytes only)

 

Recommendation:

Sample rate T ≤ 4 / fCAN message