ICP DAS USA PCI-1202 Series Hardware User Manual page 77

The A/D conversion data in FIFO are in the same sampling rate (refer to (1), (2), (3)).
For example,
* the scan channel is 1
* the pacer sampling rate is 330 k
* the expected sampling rate for channel 1 is 110 k
* the expected sampling rate for channel 2 is 55 k
* the expected sampling rate for channel 3 is 11 k
The hardware will scan the analog data into FIFO as follows:
1,2,3,1,2,3,1,2,3,1,2,3,1,2,3,1,2,3......
total 330 k
every 1,1,1,1,1 is 110 k
every 2,2,2,2,2 is 110 k
every 3,3,3,3,3 is 110 k
The software has to fetch the 2,2,2,2,2 in 55 k, therefore the software average the
continue two 2 into one 2 to get 55 k as follows:
2,2, 2,2 2,2, 2,2
2, 2, 2,
The software has to fetch the 3,3,3,3,3 in 11 k, therefore the software average the
continue ten 3 into one 3 to get 11 k.
There are very heavy computation load for the X86 to execute the MagicScan function.
These computation loads are given as follows:
1. average the continue N data into one data to get different sampling rate data
2. compare each A/D data with the HI/LO alarm limit
3. save the A/D data into memory if the save flag is enable
The MagicScan function described in this section can be realized in Pentium-120 &
Windows 95.
Refer to Sec. 4.8.6 for driver source.
Refer to Chapter 8 for demo program.
Refer to Chapter 10 for performance evaluation.
PCI-1202/1602/1800/1802 Hardware User's Manual
2 3
2, 55 k
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