Logging setup files, Logging rate, Can bus bandwidth limit – MoTeC C185 User Manual

Page 30: Maximum logging rate, Update rate, Anti-alias filter

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MoTeC

Configuration

25

Logging Setup Files

The logging list can be saved and loaded from a file. This allows multiple
logging setups to be used.

Logging Rate

The logging rate sets how often each channel is logged and can be set
individually for each channel. The C185 can store values at up to 1000 times
per second.

The rate at which the values are logged must be 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 may need 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.
For example, the engine temperature only needs to be logged at 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. See
CAN Bus Bandwidth Limit.

Note: The C185 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.

Update Rate

Each input is measured at a maximum rate which is dependent on the
capabilities of the measuring device and may also vary between inputs on that
device. For example the VIM has some inputs that update at 500 Hz and
others that update as fast as 5000 Hz. See Update Rate Summary.

Anti-Alias Filter

If a channel is logged at a rate slower than its specified update rate then an
optional anti-alias filter can be applied.

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