Omron NX-SIH400, User Manual

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Variable Designations for Function Blocks
Input parameters Output parameters
Instance name
Value is
assigned
Function block definition name or
instruction name
Input
variable Output
variable Internal
variables
Value is
assigned
The specifications for variables in function blocks are given below.
Variables
Number
*1 Specification
Input varia-
bles
1 to 64 Input variables are used as input arguments within the function block. They
cannot be changed inside the function block.
•
When the function block is executed, the input variables are set to the values
of the input parameters.
•
You can specify either constants or variables for input parameters.
•
Omitting Input Parameters:
Refer to the
NX-series Safety Control Unit Instructions Reference Manual
(Cat. No. Z931) .
Output varia-
bles
1 to 64 Output variables are used as output arguments from the function block.
•
The output parameters are set to the values of the output variables at the
end of execution.
•
You cannot specify a constant for an output parameter. Only variables may
be specified.
•
You can omit output parameter connections. If you omit an output parameter,
the value of the output variable is not assigned to any parameter.
•
Omitting Output Parameters:
Refer to the
NX-series Safety Control Unit Instructions Reference Manual
(Cat. No. Z931) .
•
You can access the values from outside of the function block. Access these
values with the following format:
InstanceName.OutputVariableName . How-
ever, you cannot write values directly to an output variable.
Internal vari-
ables
No limit Internal variables are used for temporary storage within a function block.
•
The values of internal variables are retained regardless of whether the func-
tion block is executed.
•
The values cannot be referenced from outside of the function block.
*1. The individual restrictions are listed in the above table. The actual upper limits depend on the overall pro-
gram capacity and internal memory capacity.
Refer to 6-2-4 Attributes of Variables on page 6 - 13 for details on the variable attributes that can be
set for each type of variable.
Function Block Definitions and Instances
A function block consists of a "function block definition" that is made in advance and "instances" that
are used in the actual programs.
All instances of a function block are based on the "function block definition".
A "function block definition" consists of an algorithm and a local variable table.
6 Programming
6 - 8
NX-series Safety Control Unit User's Manual (Z930)