Instruction Manual
D102748X012
DLC3010 Digital Level Controller
Configuration
May 2018
63
Analog Output Calibration
Scaled D/A Trim
Field Communicator Configure > Calibration > Secondary > Analog Output Calibration > Scaled D/A Trim (2-4-2-2)
This procedure allows trimming the gain and offset of the Digital‐to‐Analog (D/A) converter to adjust the accuracy at
which the output follows 4 to 20 mA current commands from the firmware. This relationship is initially set in the
factory, and should not require frequent user adjustment. Reasons for using this procedure include:
D Correction for component aging after the instrument has been in service for an extended period.
D Adjusting D/A calibration to be optimum at the normal operating temperature, when that temperature is
considerably removed from room temperature conditions.
The procedure is iterative, and will eventually reach a resolution limit where attempts to improve the result will cycle
at a few decimal places to either side of the target.
Follow the prompts on the Field Communicator to trim the D/A output.
1. Scale the output from 4 to 20 mA? If your reference meter is graduated in “mA”, select Proceed and go to step 5. If
the reference reading is presented in some other unit system, such as “%” or “mm”, select Change and continue
with step 2.
2. Enter the scale low output value.
3. Enter the scale high output value.
4. If the high and low output values are correct, select Proceed and continue to step 5. If they are not correct, select
Change and return to step 2.
5. Connect a reference meter across the test connections in the terminal box. See the Test Connections procedure in
the Installation section. You can also connect a reference meter in the loop as shown in figure 2‐9.
6. The Field Communicator commands the instrument to set its output to 4 mA or the low output value.
7. Enter the reading from the reference meter.
8. If the reference meter reading equals 4 mA or the low output value, select Yes and continue to step 9. If not, select
No and return to step 7.
9. The Field Communicator commands the instrument to set its output to 20 mA or the high output value.
10. Enter the reading from the reference meter.
11. If the reference meter reading equals 20 mA or the high output value, select Yes and continue to step 12. If not,
select No and return to step 10.
12. The Field Communicator commands the instrument to set its output back to the original value.
Note
If communications with the device are lost before exit of the procedure, the device may be stuck in fixed output current mode. Be
sure to check for the 'Analog Output Fixed' alert after communications are re-established, or disturb the input linkage and confirm
output current change before returning the loop to Auto.
Calibration Examples
Calibration—with Standard Displacer and Torque Tube
Run the initial calibration near ambient temperature at design span to take full advantage of the available resolution.
This is accomplished by using a test fluid with a specific gravity (SG) close to 1. The value of SG in the instrument
To Next Page
Loading...
Need help?
General
