Micromod MOD: 30MLTraining Manual - Manual (Page 241)

18 Piecewise Linearization Lab
18.1 Foreword
In many applications it is necessary to use one or more X,Y lookup tables. MOD 30ML provides
multiple piecewise blocks with up to 60 x,y pairs which provide the lookup values for the
Linearization blocks. Tuning displays can be created which allow the user to enter the X,Y
coordinates from the front panel of the controller if desired.
The piecewise table block is a data only block. The table consists of two or more pairs of X, Y
floating point coordinates (up to 60 pairs). A piecewise table can be constructed for supporting a
linearization block or as a source of floating point recipe data. In addition, the X and Y coordinates
are tunable parameters.
In this lab we will configure a piecewise block and a linearization block, and use them to linearize
steam flow to a feedwater valve position, a typical requirement in a two or three-element boiler
drum level controller. We will also construct a simple operating display and create tuning displays
that will allow entry of new X,Y coordinates from the front panel.
18.2 Objectives
In this lab, we will create a very simple two-element drum level control strategy with a steam flow
input, a drum level input, and a feedwater flow output. We will also place a piecewise table block
and a linearization block in the strategy to adjust the output before it goes to the field. In Part II we
will load a simple operating display from the Component Gallery and modify the Tune List to
include the X,Y coordinates from the piecewise table so they will appear on the controller front face
when the Tuning password is entered.
 NOTE: This lab assumes you have already completed all the standard ViZapp labs and you are
familiar with the methods of placing and connecting blocks and configuring the OPC server for
downloading to a controller.
18 - 1