3.8.2 Global Variables

Description

On the other hand, global variables defined as global can always be accessed from all job programs. If a global variable is once defined, it will not be cleared even when the program cycle is reset by an end statement or an R0 [Enter] operation of the main program.

Example

If a global x is executed first, a variable x will be created, and the value will be initialized to the default value of 0. Then, it will increase to 1 in the next row. If the global x is executed again in the next program cycle, it will not be defined again, and the value of 1 will be retained because the x has been defined. On the other hand, global y=10 will carry out defining and assignment so that the value of variable y will be reset to 10 when it is executed in the next program cycle.

0001.job	global x x=x+1 call 107 print x, y # 4, 10 end
0107.job	global y=10 print x, y # 3, 10 x=x+1 end

Therefore, if a global variable is to be utilized as a counter for the number of program cycles, no value should be assigned along with a definition.

Wrong Teaching	global count=0 count=count+1 … end
Correct Teaching	global count count=count+1 … end