ABB AC 800M Configuration page 31

Section 2 Functional Description
Explicit Messaging (Class 3 or UCMM)
Unconnected explicit messaging is used for configuration. It is transmitted over a
TCP connection.
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For class 3, communication is tag based.
CIP Connection Time-out Calculation
The Requested Packet Interval (RPI) is the requested time interval between packets
in case of Implicit communication for I/O data transfer. In the T -> O RPI
parameter on the EtherNet/IP target, the time interval between packets received by
CI873 EtherNet/IP I/O scanner from target, can be configured.
T -> O RPI value should suit the requirement of the application. The lowest value
configurable to this parameter is 10ms, which results in the fastest possible
communication.
9ARD000014-600 A
Explicit messages provide a one-time transport of data item. They can be sent
as connected or unconnected. These messages are typically point-to-point.
Explicit messages provide the typical request or response-oriented network
communications.
Predominantly used for device configuration and diagnostics.
CI873 Connections
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