Change Of State, Cos - GE AF-650 GP Operating Instructions Manual

OPCEIP EtherNet/IP

5.1.7 Change of State, COS

The event controlled operation mode is used to minimize network traffic. Messages are transmitted only if a defined state or value has changed. The condition
for triggering a COS message, is determined by the insertion of COS-filters (par. EN-38), for each bit in the different PCD-words.
The filter acts like a logical AND-function: If a bit in the filter is set to "1", the COS-function triggers when there is a change to the corresponding bit for the PCD-
word.
Parameter EN-38 can be used to filter out undesired events for COS. If a filter bit is set to 0, the corresponding I/0 Instance bit will be unable to produce a COS
message. By default, all bits in the COS filters are set to 0.
In order to signal that the connection has not been interrupted, or the device is not powered off, a Heartbeat Message is transmitted within a specified time interval
(Heartbeat Interval). This interval is defined in Attribute Heartbeat Time of the connection object, Class 0x01.
To prevent the device from producing heavy network traffic when a value changes frequently, a Production Inhibit Time is defined in par. EN-37. This parameter
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defines the minimum time between two COS messages. If par. EN-37 is set to 0, the Production Inhibit Timer is disabled.
The figure below shows the different PCD's and their corresponding filter parameters.
EN-38[0] EN-38[1] EN-38[2] EN-39[9]
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