2-12
EN
7. Select “OK” at the “Setting fld dev output to 20 mA” prompt, and repeat Steps
5 and 6 until the reference meter value equals the transmitter output value.
Select “OK” after you return the control loop to automatic control.
Scaled Digital to Analog Trim
The
Scaled D/A Trim
command matches the 4 and 20 mA points to a user-selectable
reference scale other than 4 and 20 mA (1 to 5 volts if measuring across a 250 ohm
load, or 0 to 100 percent if measuring from a DCS, for example). To perform a scaled
D/A trim, connect an accurate reference meter to the transmitter and trim the
output signal to scale as outlined in the Output Trim procedure.
NOTE
Use a precision resistor for optimum accuracy. If you add a resistor to the loop,
ensure that the power supply is sufficient to power the transmitter to a 20 mA
output with the additional loop resistance.
DIAGNOSTICS AND SERVICE
Test Device
The
Test device
command initiates a more extensive diagnostic routine than that
performed continuously by the transmitter. If the transmitter test detects a problem,
the communicator displays messages to indicate the source of the problem.
Loop Test
The
Loop Test
command verifies the output of the transmitter, the integrity of the
loop, and the operations of any recorders or similar devices installed in the loop. To
initiate a loop test, perform the following procedure:
1. From the HOME screen, Select
1 Device Setup
,
2 Diagnostics and Service
,
2
Loop Test
, to prepare to perform a loop test.
2. Select “OK” after you set the control loop to manual.
The communicator displays the loop test menu.
3. Select a discreet milliamp level for the transmitter to output. At the “Choose
analog output” prompt, select
1 4mA
,
2 20mA
, or select
3 other
to manually
input a value between 4 and 20 milliamps.
HART Comm.
1, 2, 3, 2, 2
HART Fast Keys
1, 2, 1, 1
HART Fast Keys
1, 2, 2
4690.bk : 4690.s2 Page 12 Tuesday, May 26, 1998 5:28 PM
