Automated Tasks

The automated tasks are implemented by a set of script instructions that express the outputs as a function of inputs, outputs, and parameters. For instance, in Example 1, the output oFan1 is turned on or off depending on the value of the input iT1. Strictly speaking, a variable may also be used in the expression that determines the output. However, variables themselves are functions of inputs, outputs and parameters. Strictly speaking, the output ultimately depends only on the inputs, outputs, and parameters. Example 6a implements a variable that reflects the average temperature. Then, as in Example 1, the fan is turned on or off depending on the average temperature.

Using Parameters to Change Modes

Parameters, unlike variables, are set by the user. Moreover, parameters are saved in non-volatile memory. This means, their values are preserved even if the controller loses power. Parameters are useful in implementing various modes of an automated task. The user may then switch between the modes simply by modifying the parameter value, rather than reprogramming the controller. Example 7 illustrates a simple thermostat control with two modes.

Also see : Programming, Script Syntax.