How can I convert from Modbus raw data to engineering units using a formula?

[kenv]

Within Lookout, I have several Modbus numerical input types that do not have a linear corespondence to the Engineering values they represent.  How can I display these values accurately using a formula to convert from the raw data to an engineering value?

[Mike@Forshock]

Use the built in Data Member Configuration Scaling features

In edit mode.  Using the Object Explorer go to your Modbus object and richt click.  Select Data Member Configuration, you will be presented with a screen.  Select the Register (4xxxxx) and adjust the scaling, optionally you can give the item an alias (ie. InputScaled).

Good luck,

Mike

[kenv]

I don't quite understand your reply.  I'm using Lookout 6.0.2, logged in as Administrator, in Edit Mode.  The Modbus object is named RTU06_SAV.  The Active member is 30002 with an alias of SAVfmSMT_RSL.

Following your instructions, I opened Object Explorer and right-clicked on RTU06_SAV. 

This opened a menu containing:  Refresh, Cut, Copy, Rename, Delete, Edit connections..., Edit Data Member Configuration, Configure Network Security and Properties.

I assumed that I should select Edit Data Member Configuration, but maybe I'm wrong. 

Within Data Member Configuration I can set up Linear Scaling between Raw data and Engineering data.  I know how to do that, but what I need to know is how to convert Raw data to Engineering data using a formula representing a non-linear transformation (such as a converion to a logarithmic value or perhaps a formula derived by fitting the formula to a curve on a calibration chart).

Once I have this my Engineering data can be represented on a control panel as both a numeric value AND as a correctly reading Gauge.  It can also be properly represented on a HyperTrend graph.

What do you suggest?

[Mike@Forshock]

You would first need to decide how precise this needs to be to set your polynomial values.  Then you would need to create your equations.

There is no built-in system, you would need to use the expression object to create your equation(s).

Crack open those text books! 🙂

Mike