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Chapter 3
Tag Configuration
3-14
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National Instruments Corporation
I/O Group Configuration
I/O Groups are used to configure item rate and deadband for items of a
server and to select a specific device, if the server uses devices. For servers
that support resource configuration, you also can use I/O groups to
configure devices and communication resources. For OPC servers, an I/O
group conforms to the concept of an OPC group, which is user-defined and
controls timing. An I/O Group is associated with only one server and, if that
Table 3-2.
Connection Configuration Attributes
Attribute
Applies to
Data Types
Description
Data Type
all
Determines the data type of the tag you are configuring.
BridgeVIEW tags can be analog, discrete, bit array, or string.
Tag Access
all
Determines the access rights for a tag. Tags can have access
rights of Memory, Input only, Output only, or Input/Output.
Memory tags are not directly connected to real-world I/O points.
You can use memory tags to monitor and control calculated
values and enable historical trending and alarming on these
values. Input only, Output only, and Input/Output tags are
connected to real-world I/O points according to the Server,
Device, and Item fields.
Server
all
Determines the device server that manages the communication of
the tag value. If the tag is a memory tag, this attribute is not used.
I/O Group
all
Determines the I/O Group to use for this tag. Select the I/O Group
this tag uses. The I/O Group is associated with the server. At least
one I/O Group must be created for the server in order to configure
a tag to use a server item. If the tag is a memory tag, this attribute
is not used.
Item Name
Filter
all
Determines the string to filter the list of configured items. If the
tag is a memory tag, this attribute is not used.
Item
all
Determines the register, channel, or item on the device for this
tag. This might be a PLC register, a data acquisition channel, an
OPC item ID, or a DDE item, depending on the server used for
this tag. If the tag is a memory tag, this field is not used.
Access Path
all
Determines the access path for the selected server. If the tag is a
memory tag or if the server does not have access paths, this
attribute is not used.