Emerson Rosemount 8782 Reference Manual page 73

Reference Manual
00809-0100-8782
Figure 8-1: Pulse Output
A. Open
B. Pulse width
C. Period
D. Closed
Example
If pulse width is set to 100 ms, the maximum output is 5Hz; for a pulse width of 0.5 ms, the
maximum output would be 1000Hz (at the maximum frequency output there is a 50%
duty cycle).
Pulse width
100 ms
0.5 ms
To achieve the greatest maximum frequency output, set the pulse width to the lowest
value that is consistent with the requirements of the pulse output power source, pulse
driven external totalizer, or other peripheral equipment.
The maximum flow rate is 10,000 gpm. Set the pulse output scaling such that the
transmitter outputs 10,000 Hz at 10,000 gpm.
Note
Changes to pulse width are only required when there is a minimum pulse width required
for external counters, relays, etc.
The external counter is ranged for 350 gpm and pulse is set for one gallon. Assuming the
pulse width is 0.5 ms, the maximum frequency output is 5.833Hz.
Reference Manual
A
B
C
Minimum period (50% duty
cycle)
200 ms
1.0 ms
Pulse Scaling =
Frequency =
Pulse Scaling =
Advanced Configuration Functionality
D
Maximum frequency
1 cycle
200 ms
1 cycle
1.0 ms
Flow Rate (gpm)
sec
(frequency)
(60 ) ×
min
Flow Rate (gpm)
sec gal
(60 × ) ( pulse scaling )
min pulse
350 gpm
sec gal
(60 ) × 1
min pulse
November 2019
= 5 Hz
= 1000 Hz
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