Specifications

Optimizing Performance
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Explicit messages can be sent as either connected or unconnected, depending on
the frequency of your need for data, and on the level of service required:
NOTE: The response timeout can be configured using the EM Request Timeout
parameter (located in the Channel Properties → EtherNet/IP page).
Implicit Messages
Implicit messages consist of packets of data that are time critical. Implicit messages
are used for real-time control and synchronization. Examples of implicit messages
include: real-time I/O data, motion control data, important functional diagnostic data,
real-time synchronization data, and network topology management data.
Implicit messages require determinism and high performance in message
processing and delivery.
The characteristics of implicit messaging are:
z producer/consumer mode (EtherNet/IP) or client/server mode (Modbus TCP)
z small, fixed data size
z fixed frequency
z short response time
z short connection timeout
Message type Characteristics
Connected
z Begins when an originating device initiates a connection by sending
a request to a target device.
z The connection is established when the originator receives a
successful response from the target.
z A CIP connected message has a higher priority and provides better
service, but requires a greater amount of resources from both the
target and originator devices.
z Used for recurring requests, and for high priority parameter
monitoring.
z Typically use short response timeout settings.
Unconnected
z Less resource intensive.
z Used for less frequent requests, and for lower priority parameter
monitoring.
z Typically use very long response timeout settings.