Rosemount 4600, Справочное руководство

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Reference Manual
00809-0100-4022, Rev AA
July 2002
Model 4600
4-11
Digital-to-Analog Trim
Using Alternate Scale
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 (for example, 1 to 5 volts if
measuring across a 250 ohm load, or 0 to 100 percent if measuring from a
Distributed Control System (DCS)). 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 additional loop resistance.
AMS
Right click on the device and select “Calibrate,” then “Scaled D/A trim” from
the menu
.
1. Click Next after setting the control loop to manual.
2. Select Change to change scale, click Next .
3. Enter Set scale-Lo output value, click Next .
4. Enter Set scale-Hi output value, click Next .
5. Click Next to proceed with Trim.
6. Click Next after connecting the reference meter.
7. Click Next at the “Setting fld dev output to 4 mA” screen.
8. Record the actual value from the reference meter, and enter it at the
“Enter meter value” screen and click Next .
9. Select Yes , if the reference meter value equals the transmitter output
value, or No if it does not. Click Next .
a. If Yes is selected, proceed to Step 10.
b. If No is selected, repeat Step 8.
10. Click Next at the “Setting fld dev output to 20mA” screen.
11. Repeat Step 8 - Step 9 until the reference meter equals the transmitter
output value.
12. Select Next to acknowledge the loop can be returned to automatic
control.
13. Select Finish to acknowledge the method is complete.
Fast Keys
1, 2, 3, 2, 2