Yokogawa Standalone MW100 - Manual (Page 299)

App-25
IM MW100-01E
Appendix
1
2
3
4
5
App
Index
Write Count
When data is saved to the CF card, the data is written several times in sections.
The write count can be calculated in advance.
Equation
The relationship between the data length and write count is as follows:
Data length = write length × write count
Because the write length is designed not to exceed the storage time (one-half the time
that can be stored in the internal memory), write length is less than the storage time.
Here, the storage time is derived from the storage data size and recording interval as
follows:
Storage time =
One-half the internal memory size
Storage data size
× recording interval
The storage data size is given by
Storage data size = measured data + MATH data + thinned data
Measured data: Time information 16 bytes + measured data 4 bytes × number of
recorded measurement channels
MATH data: Time 16 bytes + MATH data 6 bytes × number of recorded MATH
channels
Thinned data: Time 16 bytes + thinned data 6 bytes × number of thinning recording
channels
Thus, the write count N is given by
Write Count N >
× recording interval [s]
Data length [s]
One-half the internal memory size [byte]
Storage data size [byte]
However, the write count N is a number that divide the data length evenly.
Calculation of the Write Count
Given a recording interval of 100 ms, 60 measurement channels, and 30 minute data
length, the write count is calculated as follows:
The storage data size is given by
Storage data size [byte] = 16 + 4 × 60 [ch] = 256
Because the write length is designed to be less than a half the internal memory size of 1.25
Mbyte (when not using multi interval), the write count N is given by
Write Count N > = 7.03
× 100 ms
30 min × 60
1.25 Mbyte / 2
256 bytes
In this example, data is written 8 times (30 minutes/8 = 3 minutes 45 seconds).
Appendix 8 Saving Data to the CF Card