IPC402x-UM-2209-1-2.x.x (en)
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7.1 Events, Queues and Interrogation
Status changes of physical binary inputs and internal logical events are timestamped upon detection with a
time resolution of 1 ms. If the status change is shorter than 1 ms, the event is suppressed. Events are added
to internal queues and sent in the order of creation. The EVT LED on the device is active when events are
waiting to be transported on the system interface.
For analog signals, changes larger than the deadbands result a message which is added to the internal
queues. See Section 7.5 Analog Inputs (I/O-addressing
Analog Inputs) for detailed information about
configuration. Only the last analog message per signal is kept in the buffers.
The queues are using the principle FIFO
–
First In First Out
and can buffer a maximum of 500 events. When
a queue is full, the oldest event is discarded to make place for the last event. If the event queues are not
full, all status changes will generate time stamped event messages and no information is lost.
There are functions that will limit the creation of events when an input changes status too often. See
chapter 7.3.1 Binary Inputs
Input 1-16/22/37 for more information.
When a communication link has been initiated by the master interface, events are transmitted according to
the chosen protocol and a prioritized order (class 1 and 2 for IEC 60870-5-101/104). For IEC 60870-5-104,
the events are sent immediately when they have been added to the queues. If IEC 60870-5-101 is used, the
events are transmitted after requests from the master interface.
At general interrogation, events are created for all objects defined in the device. The current status of all
input signals, physical and logical, are collected and added to internal queues with no delay. The events are
sent in the order they have been added to the queues.
If the IPC device is acting master for other slaves, it will collect events from all active slaves. Due to speed
limitations in the master-slave transmission there will be a delay until all status updates are retransmitted
to the control center.