MoTeC ACL VIM - Manual (Page 21)

MoTeC Operation 17
Start and Stop Logging Conditions
To avoid logging data unnecessarily, logging can be started and stopped by
user definable conditions. For example, logging might start when the vehicle
exceeds 50 km/h, and stop when the engine RPM is below 500 RPM for 10
seconds.
Note The Start Condition must be true and the Stop Condition must be false
before logging will start.
Memory Filling Options
When the logging memory is full the ACL will stop logging. However there is
an option to cycle through the available memory.
Logging Rate
The logging rate sets how often each channel is logged and can be set
individually for each channel.
The rate at which the values are logged is very important – the value must be
logged fast enough to record all variations in the reading. If the value is
logged too slowly, the readings can be totally meaningless. For example,
suspension position normally needs to be logged at 200 times per second or
more.
However, if a value is logged faster than necessary it will not improve the
accuracy of the logged data, it will just reduce the total logging time available
and increase the logging unload time. For example, the engine temperature
only needs to be logged once per second.
CAN Bus Bandwidth Limit
High logging rates also increase the amount of data that is being
received from the measurement devices which increases the amount of
data on the CAN bus. This can lead to exceeding the CAN bus
bandwidth limit. Refer to Appendix F: CAN Bus Bandwidth Limit.
Note The ACL Manager will warn if the bandwidth is likely to be
exceeded.
Maximum Logging Rate
The maximum logging rate is limited to the update rate of the particular
channel. This varies significantly depending on the source of the
channel. For example, some VIM inputs update at 5000 Hz, whereas
some communications devices may only update at 50 Hz. Also some
internal calculations may be limited to 100 Hz.