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The following QuickMode example shows how to calculate the approximate amount of time from powering
on an MNU IS sensor until the first reading is reading is written in Input Register 30300.
Register settings for this QuickMode example:
•
Max Distance
(40405): 4572 mm
•
Pulses
(40409): 5 (pulses per sample)
•
QuickMode Delay
(40422): 0 (milliseconds)
•
QuickMode samples
(40421): 5
Total Time = Base Time + Distance Adju Effective QuickMode Delay
Base Time = (
QuickMode Samples
x 100) + 150
Base Time = (5 x 100) + 150 = 500 + 150 = 650 ms
Distance Adjustment = (
QuickMode Samples
x 10) x ( (
Max Distance
/ 1829) - 1)
Distance Adjustment = (5 x 10) x ( (4572 / 1829) - 1) = 50 x (2.5 - 1) = 50 x 1.5 = 75 ms
Effective QuickMode Delay =
QuickMode Delay
- 250
Since
QuickMode Delay
counting begins at Power On, the 250 ms of Start up time must be subtracted
from any value over 250.
QuickMode Delay
values between 0 and 250 have no effect on the timing.
Total Time = 650 ms + 75 ms + 0 ms = 725 ms
If the target is closer than the maximum distance, the Travel Time will lessen accordingly, thus bringing
down the Total Time.
For MNU IS sensors used in a redundant configuration, figure the Total Time for the first sensor, add at least
250 ms (a quarter second) for time between the two sensors, and use the sum as the
QuickMode Delay
for
the second sensor.
Using the example set up above, a redundant sensor should have a
QuickMode Delay
of at least 975 (725 +
250).
•
QuickMode Timing Example
NOTE
: A Modbus Master with only one MNU IS operating in QuickMode can be set to
be ready to receive the response packet immediately after sending the QuickMode Sam-
ple/Resample instruction in order to avoid making the timing calculations.
NOTE
: Sound waves are affected by the physical environment, including temperature
and elevation. These calculations are based on observations at ~4550’ and 21
°
C.
