Campbell Scientific SDM-INT8 8-Channel Interval Timer - Manual (Page 36)

Appendix B. Processing Time Limitations
If the Tt for Output Option XXXX is greater than the specified interval, the
extra time will be added to the execution time of Instruction 101.
Example 1
Given:
Output Option = XXXX
Specified interval = S = 500 ms
Function = frequency (Function 2)
Number of channels measured = N = 6
Average input frequency = F = 1kHz
Find: Total Processing Time, Tt
Solution:
Tt = To+ΣTi = To+T2
= 0.511*S+Et*(.034+.010*N) +0.015*E2
= 583 ms
S = 500 ms
N = 6
Et = N * S * F = 3000
E2 = Et = 3000
In this case 83 ms is added to the execution time of Instruction 101.
Example 2
Given:
N = number of channels measured
F = Frequency of input signal, kHz
Function = frequency (Function 2)
Output Option = 0 or 0--
Find: Maximum average frequency, F, at which the processing time is ≤ the
measuring/storing time.
Solution:
Tt must be ≤ to S;
To+T2≤S
0.511*S +Et*(.034+.010*N) + 0.015*E2 ≤ S
Note: Et = E2 = N*F*S
0.511*S+N*F*S*(.034+.010*N)+
0.015*N*F*S
≤S
F<.489/(N*(.049+.01*N))
Results for the above example using all Functions is presented in TABLE 2,
Section 5.4.1
B-2