Revision 5.0
ST 800 Series HART/DE Option User’s Manual
Page 71
7.2 Analog Output Signal Calibration
With a Transmitter in its constant current source mode, its analog output circuit can be calibrated at
its 0 (zero)% and 100% levels. It is not necessary to remove the Transmitter from service.
The following procedure is used for analog output signal calibration.
You can calculate milliamperes of current from a voltage measurement as follows:
Dc milliamps = 1000 X voltage/resistance
IMPORTANT: Be sure that the accuracy of the resistor is 0.01% or better for current
measurements made by voltage drop
.
1.
Connect the MC Toolkit across loop wiring, and turn it on. See
Error! Reference source not
found.
for a sample test equipment hookup.
2.
Launch the FDC application.
3.
On the Home page, select Online and establish a connection with the device as follows;
4.
Select the My Device menu, and choose from the following menus:
a.
Device setup \ Calibration \ Calibration Methods \ D/A trim
5.
You will be prompted to remove the loop from automatic control; after removing the loop
from automatic control, press OK.
6.
When a prompt appears, connect a precision milliammeter or voltmeter (0.03% accuracy or
better) in the loop to check readings, and press OK. The following prompts will be displayed:
•
Setting field device to output to 4mA. Press OK
•
Enter meter value. Key in the meter value, and press ENTER.
•
Field device output 4.000 mA equal to reference meter?
1 Yes
2 No
If the reference meter is not equal to the field device output then select No
and press Enter
Key in the new meter value
Return back to the ”Enter Meter Value” prompt until the field device output
equals the reference meter
Select Yes and press Enter
7.
The following display prompts will appear:
•
Setting field device output to 20mA. Press OK
•
Enter meter value. Key in the meter value, and press ENTER.
•
Field device output 20.000 mA equal to reference meter?
•
1 Yes
•
2 No
o
If the reference meter is not equal to the field device output then select No
and press Enter
o
Key in the new meter value
o
Return back to the ”Enter Meter Value” prompt until the field device output
equals the reference meter
o
Select Yes and press Enter
8.
The prompt notifies you that the field device will be returned to its original output
