5-7
Exposing Variables to Standard Con-
trollers
This section describes how to control and monitor a Safety CPU Unit from a standard controller
through standard process data communications.
5-7-1
Exposing Global Variables
When you set global variables in the Safety CPU Unit for standard process data communications, the
variables are exposed as I/O ports in the I/O Map of the CPU Ruck or Communications Coupler Unit. If
the exposed variables are assigned to the I/O ports when you use an EtherCAT Coupler Unit, you can
access the global variables in the Safety CPU Unit from programs in the NJ/NX-series CPU Unit.
When the target unit is connected to the CPU Unit or the EtherCAT Coupler Unit is used, the global
variable of the Safety CPU Unit can be accessed using the program of the NJ/NX-series CPU Unit by
allocating the variable to the exposed I/O port.
The I/O Map of the NJ/NX-series CPU Unit displays the data types that correspond to the data types
of the exposed Safety CPU Unit variables.
The following table gives the variable data types that can be exposed for Safety CPU Unit and the cor-
responding data types that are displayed for the NJ/NX-series CPU Unit.
Variable data type that can be exposed for Safe-
ty CPU Unit
Data type displayed for NJ/NX-series CPU
Unit
Data size
in bytes
BOOL BOOL 1
BYTE USINT 1
WORD UINT 2
INT INT 2
DINT DINT 4
The variables that can be exposed for the Safety CPU Unit are restricted as given in the following ta-
ble.
Item Restriction
Number of exposed variables Inputs 254 variables max.
Outputs 253 variables max.
Precautions for Correct Use
• There is a restriction on the data size that can be communicated between the Safety CPU
Unit and the NX bus master, as well as the restrictions on the number of exposed variables.
This data size limit includes FSoE communications and CIP Safety communications. Y
ou can
check the usage on the Memory Usage Pane of the Safety CPU Unit.
• If the settings cause a limit to be exceeded, a red "!" icon is displayed by Exposed Variables
in the Multiview Explorer.
5 System Configuration and Setup
5 - 30
NX-series Safety Control Unit User's Manual (Z930)
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