Installation and Operations Guide
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Initial firmware and operator workstation setup
© Honeywell. All Rights Reserved. LT-VLXEXPAXMIOG Rev. 01
55
Zero and Range AVs are identified as follows:
AV- e4nn = Zero
AV- e5nn = Range
The AI is derived from the input raw counts and Zero and Range values as
follows:
By adjusting Zero and Range AVs, the AI can be scaled to any range desired.
Use the following information and “Appendix B: Scaling factors” on page 75 to
determine scaling factors for common applications.
Setting up software input filtering The VLX/ACM-VLX enables you to set up
software input filtering. Filtering is useful if the input signal includes extraneous
fluctuations, either for electrical or physical reasons. For example, flow pressure
signals can sometimes fluctuate due to turbulence in the pipe. Use the filter to
damp the response and stabilize the input reading.
A pair of AVs controls input filtering:
• AV- e1nn determines whether the input is to be filtered. When 0, no
filtering is applied. When 1, filtering is ON.
• AV- e2nn is the filter factor. This value applies only when filtering is
ON. This factor can be set in the range 0–255. A higher factor results in
a greater degree of filtering (see the filtering equation).
The software input filter adjusts the AI present-value as follows:
c = Raw counts
y = Filter factor set through AV-e2nn
p = The previously calculated AI present-value (post filtered)
4–20mA Read internally as 1–5V, so counts range from 800–
4000.
Resistive
(potentiometer)
As the potentiometer moves from 0–10K Ohm, raw
counts move from 0–2048 (half the full range).
Application conditions and the precision rating of the
potentiometer may cause variations. Confirm the raw
count reading when the potentiometer is at minimum and
at maximum. Then scale the input. Use this equation to
calculate the theoretical count that results from a given
resistance:
0–5VDC Counts range from 0–4000 (0V–5V).
0–10VDC Counts range from 0–4000 (0V–10V).
AI Present Value Zero
Input Raw Counts
4095
------------------------------------------- R a n g e+=
Counts
4095 R
10 000 R+
----------------------------
=
AI Present Value
c 256 y–
256
-------------------------------
py
256
-------------
+=
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