Creating custom measurements in OpenHistorian

Is there any option to create a custom measurement in openHistorian such as a new voltage measurement which differs by a constant with respect to another existing voltage measurement?

FYI, all measurements include an Adder and Multiplier for linear adjustments (e.g., y=mx + b). This adjusts the original measurement. To keep the original measurement value, you can create a clone of the source measurement with its own adjustment, like you suggest. Here are some steps:

The following instructions are executed from the openHistorian Manager (UI app, not web page):

Step 1: Create new output measurement:

  1. Navigate to Metadata > Measurements
  2. Go to last page (>> button on bottom right)
  3. Click (+) Add New button
  4. Enter a tag name, e.g., MY-NEW-VOLTAGE
  5. Enter a signal reference, e.g., MY-NEW-VOLTAGE-PM1
  6. Enter a description, e.g., My new voltage
  7. Optionally select device from drop-down measurement will be associated with
  8. Select measurement type, e.g., Voltage Magnitude
  9. Apply an adder or multiplier, like 1.732 (your constant offset)
  10. Check the Enabled checkbox
  11. Click Save

Step 2: Copy input measurement value to new output measurement:

  1. Navigate to Actions -> Manage Custom Actions
  2. Go to last page (>> button on bottom right)
  3. Click (+) Add New button
  4. Enter a name for the adapter, e.g., SET-MY-NEW-VOLTAGE-VALUE
  5. Select Dynamic Calculator from adapter type list
  6. Enter the following adapter parameters:
    a) ExpressionText: x
    b) FramesPerSecond: 30
    c) LagTime: 5
    d) LeadTime: 5
    e) OutputMeasurements: MY-NEW-VOLTAGE < Just pick from list
    f) VariableList: x = PPA:99 < Set to your input voltage measurement
  7. Check the Enabled checkbox
  8. Click Save
  9. Click Initialize

You should now have a value in the MY-NEW-VOLTAGE measurement that is a copy of your input measurement offset by you applied adder / multiplier.

FYI, see examples for possible complex calculation expressions for the dynamic calculator. Technically you could have applied the adjustment in the expression like so: ExpressionText: x * 1.732 and left the MY-NEW-VOLTAGE multiplier set at 1.0.