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. 12-38), 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 12-38 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. 12-37. This
parameter defines the minimum time between two COS messages. If par. 12-37 is set to 0, the Production Inhibit Timer is disabled.
The figure below shows the different PCD’s and their corresponding filter parameters.
5 How to Control MCA 121 EtherNet/IP
24
MG.90.J2.02 - VLT
®
is a registered Danfoss trademark
5
To Next Page
Loading...
Need help?
General
