Specifications

Allen-Bradley ControlLogix Ethernet Driver Help
Glossary
Term Definition
Protocol Mode The means by which Controller tag addresses are specified in data access communication
packets.
Default Type Due to the symbolic nature of Logix tag-Based Addressing, tags can be of any data type.
This is in contrast to DF1 where file access (such as N7:0) is always a given set of data
types (Word, Short). Because of this flexibility, there needs to be a data type that tags
default to when no data type is explicitly set. This is the case when a tag is created in a
client and assigned the data type "Native" or created in the server and assigned the data
type "Default". In these cases, the tag in question is assigned the data type set as the
default type. There are also cases in Automatic Tag Database Generation where the default
type is used to set a server tag's data type.
Gateway Utilizing an Ethernet/IP communication module to obtain access to a DH+ or ControlNet
network from the same backplane. Rack must contain an Ethernet/IP communication
module and a DHRIO or CNB module.
Link Address Unique identifier for an interface module (such as node ID, IP address and so forth).
Packet Stream of data bytes on the wire representing the request(s) being made. Packets are
limited in size.
Logical Mode A Protocol Mode in which Controller tag addresses are specified by their logical address in
the controller. This provides a performance increase over Symbolic Mode but requires a
project upload to gather the logical addresses. There are two logical addresses that can be
used. If the controller revision is V20 or lower, the logical address is the Physical (DMA)
address. If the controller revision is V21 or higher, the logical address is the Symbol
Instance ID.
Non-Blocking: Each client/server tag is requested individually from the device. Similar to
Symbolic in nature but much faster in performance.
Blocking: Each Controller tag is requested as a single block of data. Each client/server tag
is updated via cache storage of this data in the server. Much faster performance over
Symbolic Mode.
Port ID Specifies a way out of the interface module in question (such as channel).
Project
Synchronization
Synchronization of the driver's project image with that of the controller project. This is
required for the Logical Protocol modes.
Routing Utilizing one or more Logix racks to hop to another Logix rack.
Symbolic Mode A Protocol Mode in which Controller tag addresses are specified by their ASCII character
equivalent. Each client/server tag is requested individually. This provides immediate
access to controller data without a project upload but is overall slower in performance
when compared to any of the Logical Modes. When the default data type is set to Default,
the tag data types are returned from the controller during automatic tag database
generation.
Tag Division Special assignment of tags to devices whose Protocol Mode is set for Logical Blocking or
Logical Non-Blocking Mode. Assignment is based on rules that maximize the performance
of access to these tags.*
*For more information on tag division, refer to Performance Statistics and Tuning and Optimizing Your
Communications.
Logix Tag-Based Addressing
Term Definition
Array Element Element within a Logix array. For client/server access, the element must be an atomic. For
example, ARRAYTAG [0].
Array with
Offset
Client/server array tag whose address has an array element specified. For Example,
ARRAYTAG [0] {5}.
Array w/o
Offset
Client/server array tag whose address has no array element specified. For example,
ARRAYTAG {5}.
Atomic Data
Type
A Logix, pre-defined, non-structured data type. Example: SINT, DINT.
Atomic Tag A Logix tag defined with an Atomic data type.
Client An HMI/SCADA or data bridging software package utilizing OPC,DDE, or proprietary
www. kepware.com
124