User-Defined Scale - Spectrum Controls SLC 500 User Manual

3-10 Chapter 3: Configuring the 1746sc-INO4I
User's Manual Pub. 0300128-04 Rev. A
Your module will now limit the output signal as shown below.
Note that whenever the requested output data values meet or attempt to exceed
the output data limits, your module sets bits 10 or 11 in the channel status word
to indicate a limit error. Note also that words 0 through 3 of the input image file
(addresses I:e.0 through I:e.3) reflect the requested output data values and are not
truncated.

User-Defined Scale

For special applications, the 1746sc-INO4i and 1746sc-INO4vi output modules
let you define a custom data format. This "user-defined scale" is very similar to
the "proportional counts" data format—except that instead of converting the
output data to an output signal using a previously defined scale (-32,768 to
32,767), your module converts the output data using a scale defined by the values
in output words 6 (low limit of scale) and 7 (high limit of scale).
The high limit value must be greater than the low limit value for proper
operation. Also, the difference between the low and high values should be greater
than 1024 counts. If the difference between the low and high values is less than
1024 counts, unexpected results can occur (especially at the extreme ends of the
range).
You select the data format for each channel using that channel's configuration
bits, described in the previous subsection, Configuring Each Output Channel.
The following equations show you how to convert user-defined scale units (or
any type of units) to engineering units, and vice versa:
S = {(U - U ) × (∆S) ÷ (∆U)} + S
low
D = {(S - S ) × (∆U) ÷ (∆S)} + U
low
where S = signal value (in engineering units, such as psi)
S = low limit of signal value
low
low
low