Rockwell Automation 57C610 Enhanced Basic Language, AutoMax - Manual (Page 26)

4Ć6
an application task allocates space for 21 string values of 10
characters each. Note that if no length is specified in the initial array
reference, the default maximum is 31.
To define an array that will be common, i.e., accessible to all tasks in
the rack, you need to first define the variable. If you are using
AutoMax Version 2.1 or earlier, this is done with a MEMDEF or
NVMEMDEF statement in the configuration task for the rack. If you
are using AutoMax Version 3.0 or later, common variables are
defined within the Programming Executive. For example,
ARRAY1@(10) will allocate space for 11 boolean variables. Then, in
an application task for the rack, you declare the array a COMMON
variable as follows:
COMMON ARRAY1@(10). Each element of the array that will be
used in the task can be defined with LET statements as follows:
LET ARRAY1@(0) = TRUE (boolean values can only be
TRUE/FALSE or ON/OFF). Other application tasks in the rack can
access the value in variable ARRAY1@(0) simply by declaring it a
COMMON variable.
4.1.3 Variable Control Types
The control type of a variable refers to the way the variable is
declared or defined in the configuration and application tasks. There
are two control variable types in AutoMax systems, local and
common.
1. Local
Local variables are variables that are not defined in the rack
configuration and are therefore accessible only to the
application task in which they are defined. BASIC and Control
Block tasks must define the variables with a BASIC LOCAL
statement. For Ladder Logic/PC tasks, the editor prompts for
whether the variable is local or common when the task is being
created.
In BASIC and Control Block tasks, local variables can be
defined as tunable. Tunables are variables whose value can be
tuned, i.e., changed within limits, by the operator through the
OnĆLine menu of the Executive software. The value of tunable
variables can also be changed by application tasks by using the
BASIC languange WRITE_TUNE function. BASIC and Control
Block tasks must define tunable variables with a variation of the
BASIC LOCAL statement that includes the tuning parameters.
Ladder Logic/PC tasks cannot use tunable variables.
The value of local variables at the time of initial tasks installation
is always 0. The effect of a Stop All or a power failure on variable
values in the rack depends on the variable type. Local tunable
variable values in both AutoMax and UDC application tasks is
always retained. Local variable values are retained for AutoMax
tasks, but not for UDC tasks.
AutoMax Processors will retain the last values of all local
variables. UDC modules will retain the variable values for the
following: parameter configuration data, UDC test switch
information, and D/A setup configuration. The variable values of
the following input data will also be retained: feedback registers,
UDCĆPMI communication status registers, and UDC task error
log information. UDC modules will NOT retain local variable
values and data found in the following registers, which are