Using A Frequency Counter To Read The Rpr Signal - Emerson Fisher 846 Instruction Manual

Type 846 and Model 3311
POWER
SUPPLY
NOTE:
1
IF A HART COMMUNICATOR IS NOT AVAILABLE, A FREQUENCY COUNTER
CAN BE USED IN ITS PLACE. SEE TEXT TO CONVERT THE FREQUENCY DISPLAY
TO OUTPUT PRESSURE
B2466/IL Figure 5-1. Wiring Connections for the HART
A6646/IL
Figure 5-2. HART Communicator ON/OFF Key
A6647/IL
Figure 5-3. HART Communicator Main Menu
When the HART Communicator is not connected to
a HART compatible device, the first menu to appear
after powering is the Main menu.
From within the Main menu, you can access the
Frequency Device menu (figure 5-4) by pressing
the 4 key.
5–2
CONTROLLER
FREQUENCY
COUNTER
R
Communicator or a Frequency Counter
A6648/IL
Figure 5-4. HART Communicator Frequency Device Menu
Using a Frequency Counter to Read the RPR
Signal
A frequency counter also can be used for Remote
Pressure Reading. The frequency counter displays
the RPR output in the same manner as the HART
communicator, but the output frequency must be
converted to output pressure using a simple
mathematical formula. To determine the output
pressure, subtract 5,000 Hz from the frequency
displayed on the frequency counter, and then divide
by 100.
Conversion Formula
Display Hz – 5, 000 Hz
Example:
5, 311 Hz – 5, 000 Hz
Instruction Manual
Form 5739
February 2002
TEST
PINS
+ psig
100
+ 3.11 psig
100
POSITIVE
NEGATIVE
GROUND