5.6 D/A Trim Procedures - LOI
5.6.1 O
2
D/A trim procedure using the LOI
Use the following procedure to perform the O
2
D/A trim procedure at the LOI. Refer to the LOI
menu tree in Figure 4-5.
To avoid a potentially dangerous operating condition, the Hazardous Area OCX 8800
must be removed from the automatic combustion control loop before you start the D/A
trim procedure.
1. From the operating display use the left-pointing key to select the first column submenu.
Use the down-pointing key to select SYSTEM.
2. From the SYSTEM menu, use the down-pointing key to select Input/Output. Use the
right-pointing key to select the Analog parameters list.
3. Scroll down to the item Trim O2 Out. Touch the right-pointing key to start the O
2
trim
procedure.
NOTE
If you wish to exit D/A Trim with no changes, step through the procedure using yes responses,
and enter no meter readings.
4. Remove the electronics housing cover.
5. Refer to Figure 2-6. Connect a digital multimeter to read the milliamp output from the
O
2
D/A converter circuit. Connect the positive lead to the AOUT1+ terminal and
connect the negative lead to the AOUT1- terminal. Then, touch the Enter key at the LOI.
6. The LOI displays 4 mA........Meter. The trim program inputs the design-equivalent signal
for a 4.00 mA output. Read the O
2
milliamp output at the digital multimeter. Use the
right-pointing key to select each digit and use the up- and down-pointing keys to
change the value. When the correct value is displayed, use the Enter key to input the
value.
7. The LOI displays 20 mA........Meter. The trim program inputs the design-equivalent
signal for a 20.00 mA output. Read the O
2
milliamp output at the digital multimeter.
Use the right-pointing key to select each digit and use the up- and down-pointing keys
to change the value. When the correct value is displayed, use the Enter key to input the
value.
8. The LOI displays a Meter at 4 mA prompt. Use the right-pointing key to select the letter
yes or no. Use the up- or down-pointing key to change the letter. Then use the Enter key
to input the response. If no, the process repeats from step 7.
9. The LOI displays a Meter at 20 mA prompt. Use the right-pointing key to select the letter
yes or no. Use the up- or down-pointing key to change the letter. Then use the Enter key
to input the response. If no, the process repeats from step 8.
10. When the ropiness in steps 8 and 9 are yes, the trim procedure is complete. Exit the LOI
menu and return the control loop to automatic control.
D/A Trim Procedures - LOI 75
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