CAAPE User's Manual - ALSTOM Signaling Inc.

Using CAAPE GraphicsEquation parameters are displayed using various types of symbols depending on:• Whether they are complemented.• Whether they are normally open or normally closed. These terms refer to thequiescent state of the relays the variables represent; the quiescent state affects howa variable is represented but has no effect on how the equation is executed in thelogic.• What symbol set (e.g. ladder logic, straight line or drop line) is selected.For time delay equations (equations whose response to changes in input may bedelayed by a specified time), the time delay values are considered part of the"properties" of the equation. Some equation properties such as equation type and timedelay are displayed in an equation’s statement header.In Figure 6–12 an equation is shown using Drop Line symbols. The result, A4WVR, isdisplayed at the right. Three elements are AND’ed together to get the result: the singlevariable 4WRCS at the left, and two parallel combinations of two branches each. As textthe logic of the equation isBOOL A4WVR = (4WRCS *((4WH * .N.B4TP) + (.N.A4TP * A4WVR)) *((124NWC * 4CTP) + (124RWC * A2TP)))• “*” is an AND operation• “+” is an OR operation• “.N.” is a logical complement (NOT).Figure 6–12. Ladder Logic Boolean Equation DisplayP2512A, Rev. Oct/09 6–20 Alstom Signaling Inc.