FINE ALIGNMENT PROCEDURE
The Fine Alignment procedure should be completed
when maximum optical signal strength is required, such
as most outdoor applications and all installation areas
with high levels of optical contamination or fog.
It is necessary to complete the Basic Alignment
procedure before starting the Fine Alignment
procedure. A handheld HART communication device
such as the intrinsically-safe Emerson Model 375 HART
communicator is required to complete Fine Alignment.
HART Field Communicator Recommendations
• Ensure that the HART communicator is certified for
use in classified areas.
• The HART communication device used for Fine
Alignment must include the OPECL device descriptor
(DD) software menu. The use of HART
communication devices without the proper DDs may
establish generic mode HART communication, but will
not enable Fine Alignment to be completed. Refer to
the HART appendix for additional information.
• A minimum level of understanding with regard to the
operation and navigation of the HART communicator
is required to complete the Fine Alignment procedure.
Please refer to the appropriate HART communicator
instruction manual for basic operating instructions if
required. Additional information on the use of the
HART communicator is provided within the HART
Appendix in this document.
• For proper HART communication to occur, it is
required that a 250-500 ohm resistive load be present
in the OPECL analog 4-20 mA signal loop output.
Procedure
After completion of the Basic Alignment procedure,
perform the Fine Alignment procedure as follows:
1. Connect the handheld HART communicator to the
receiver module’s onboard HART communication
port.
2. Turn on the HART communicator and check for
OPECL device recognition. When HART
communication is established, the OPGD Rx Root
menu will be displayed on the Communicator
display screen.
3. From the Root menu, select the Status Menu
(selection #2).
4. From the Status Menu, select the Sensor Information
Menu (selection #3).
5. The Sensor Information Menu will display the
following screen.
6. Observe the Gas Gain level indicated on the Sensor
Information Menu screen.
7. Adjust the transmitter in both the vertical and
horizontal directions slowly and in small increments
to a position where the Gas Gain level is minimized.
NOTE
Turn the pan-tilt bolts only a fraction of a turn at a
time.
8. Similarly, adjust the receiver in both the vertical and
horizontal directions slowly and in small increments
to a position where the Gas Gain level is minimized.
9. Table 4 can be used as a guideline for new
installations to assess Gas Gain level with proper
alignment.
NOTE
Do not attempt to tighten any threaded adjuster
bolt if the opposing adjuster bolt is tightened hard
against the mounting plate hardware. It is
necessary to slightly loosen the opposing adjuster
bolt in all cases before attempting to tighten an
adjuster.
NOTE
Adjust the horizontal alignment angle first in small
increments. After an adjustment is made, wait for
at least 10 seconds for the Gas Gain display level
to stabilize. Adjust left and/or right, if necessary,
until the correct level is achieved.
19
95-8556
2.1
Distance (m) Standard Range OPECL Long Range OPECL
20
1 - 2
NA
40
2 - 3
NA
60
4
2
80
NA
2-3
100
NA
3
120
NA
3-4
Table 4— Expected Gas Gain Settings for Standard and Long
Range OPECL vs Distance
1) Active
XXX
2) Reference
XXX
3) Ratio
XXX
4) Gas Gain
X
5) Absorption
XXX
Gas Gain number
(adjust to minimum level)
