Type: a = 5; and press Enter

You should see the following on the screen:

--> a = 5;
5

You have just created a symbol (a) and assigned it a value (5). That symbol is a variable, and is now available to the Gamma engine until the DataHub instance shuts down. Notice that the Script Log inserts a prompt (-->) and shows your command to help you identify what you typed in.

Press the Clear button to clear the Script Log. Press the Close button to close the Script Log window, then reopen it.

Type: a; and press Enter

You should see the following on the screen:

--> a;
5

Sure enough, the value of a is still in the Gamma engine.

Type: princ("Hello world.\n"); and view the results:

--> princ("Hello world.\n");
Hello world.
t

Why the t? It is the return value from the princ function, a logically true value. Every Gamma function returns a value. The string 'Hello world.' is the byproduct or result of running the function, but the actual return value is t. For more details on Gamma programming, please refer to the Gamma manual.

Now, let's see a value in the DataHub instance. Start DataSim, then type: $DataSim:Sine; and press Enter. You should see something like this:

--> $DataSim:Sine;
-0.47552825816976968

This was the value of the Sine point in the DataSim domain of the DataHub instance at the moment you pressed the Enter key.

	The colon character (:) is used to divide the domain name from the point name. The dollar sign character ($) tells the Gamma engine that the colon is part of the variable name, not a syntactic element.

You can re-enter up to the last 10 commands by pressing the down arrow on your keyboard. Try it now. Press the down arrow until you see the last command, $DataSim:Sine;, and press Enter. Try it several times. You will get different values because the DataSim program is running.