4-9
Transmitter Functions
Pulse Width Pulse Width, or duration, of the frequency output pulse can be
adjusted to match the requirements of different counters
or controllers (See Figure 4-1). The pulse width adjusts the
time that the switch is closed.
FIGURE 4-1. Pulse Output.
Example
For example, if pulse width is set to 100 ms, the maximum output is 5
Hz; for a pulse width of 0.5 ms, the maximum output would be 1000 Hz.
(At the maximum frequency output there is a 50 percent duty cycle.)
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.
HART Fast Keys
1, 4, 3, 3, 2
LOI
Detailed Setup
Pulse
Width
Period
OPEN
CLOSED
PULSE WIDTH MINIMUM PERIOD
(50% duty cycle)
MAXIMUM FREQUENCY
100 ms 200 ms
0.5 ms 1.0 ms
1 Cycle
200 ms
----------------
5Hz=
1 Cycle
1.0 ms
---------------
1000 Hz=
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