Page 70
ST 700 Series HART/DE Option User’s Manual
Revision 4.0
8.2 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.
2.
Launch the FDC application.
3.
On the homepage, click Online and establish a connection with the device as follows;
4.
Click 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 millimeter 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 4.000mA equal to reference meter?
1 Yes
2 No
a.
If the reference meter is not equal to the field device output then click No and
press the
Enter Key
in the new meter value.
b.
Return to the
Enter Meter Value
prompt until the field device output equals
the reference meter
c.
Click 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
a.
If the reference meter is not equal to the field device output then click No and
press
Enter
.
b.
Key in the new meter value.
c.
Return to the
Enter Meter Value
prompt until the field device output equals
the reference meter.
d.
Click
Yes
and press
Enter
.
8.
The prompt notifies you that the field device will be returned to its original output
