Appendix A. Model
CN1100LX Specifications
Doc.#6000-0015 Rev: A
Page 41
Sampling
Sampling Limits
•
The CN1100 will sample, average and trigger detect at a
maximum continuous rate of 100Hz.
•
Between 100 Hz and 500Hz sampling rate, the CN1100 can only
record and transmit data; averaging and trigger detection cannot be
performed with four active SIOs.
•
At 1Khz and four active SIOs the unit can only record data then
transmit after completion of data acquistion. Also, averaging and
trigger detection cannot be enabled. Users need to run in the
following burst mode: (refer to Softsens manual )
o
Issue a "DAQ_OFF" command to stop data acquisition.
o
Set the sampling rate to 1Khz.
o
Issue a "DAQ_ON" command to start data acquisition.
o
To stop acquisition issue a “DAQ_OFF” command
o
Transfer the data.
Data Throughput
The following tables benchmark typical block data transfer times between
the Crossnet node and a PC using a PCMCIA (Bluetooth radio card) or a
serial port BT110. Data requests are made to the Node to transfer all new
data acquired since the last data transfer request. Data is transferred in
blocks; longer transfer times imply larger data block sizes and also greater
latency.
The fastest transfer mode is the Raw mode; scaling to engineering units
(EU) on the local PC. Requesting EU units from the Node requires floating
point conversion and increases the latency; in some cases the system cannot
maintain a continual flow of data.
Applications requiring low latency should use the Raw mode; applications
that log data or don’t care about latency can use the EU modes. Either using
fewer SIOs or decreasing the sampling rate can improve data transfer rates.
For example, in the table below, changing the sampling rate from 500Hz (2
msec) to 333Hz (3 msec) changed the transfer time (EU mode) from 2.2
sec to 0.25 sec.
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