X20 system modules • Counter modules • X20DC2395
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X20 system User's Manual 3.10
4.11.14.12.5.2 Edge events
For each physical input channel there are 3 event functions
•
Falling edge
•
Rising edge
•
Falling and rising edge
The respective event is triggered when an edge is detected on the hardware input and the "CfO_EdgeDetectRising"
and/or "CfO_EdgeDetectFalling" register has been configured for the respective channel.
Edges are detected by the hardware and processed for each interrupt. The interrupt handler uses an event distrib-
utor, which requires a specific amount of time for each edge to operate the hardware and execute linked event
functions. To reduce this time, edge detection can be enabled/disabled individually for each channel. To optimize
system load and I/O jitter, it is important to only enable edge detection where it is actually needed.
Information:
Edge detection can also be used for channels that are configured as outputs.
Event frequency limitation
To stabilize the system, there is a mechanism that limits the number of events created through edge recognition.
At least one idle event must occur between two edge events for the same edge.
The "CfO_FallingDisProtection" and "CfO_RisingDisProtection" registers can be used to disable this limitation for
each edge, and then an event will be generated for every edge. However, this can cause a system overload, i.e.
I/O operation can fail for up to 100 ms before the module changes to the reset state.
Generate event on falling edge
Name:
CfO_EdgeDetectFalling
This register defines whether an event is generated on a falling edge.
Data type
Value
USINT
See bit structure.
Bit structure:
Bit
Description
Value
Information
0
No event generated on falling edge.
0
Channel 1
1
Events 4096 and 4128 are generated on falling edge.
...
...
0
No event generated on falling edge.
3
Channel 4
1
Events 4099 and 4131 are generated on falling edge.
4 - 7
Reserved
-
Generate event on rising edge
Name:
CfO_EdgeDetectRising
This register defines whether an event is generated on a rising edge.
Data type
Value
USINT
See bit structure.
Bit structure:
Bit
Description
Value
Information
0
No event generated on rising edge.
0
Channel 1
1
Events 4112 and 4128 are generated on rising edge.
...
...
0
No event generated on rising edge.
3
Channel 4
1
Events 4115 and 4131 are generated on rising edge.
4 - 7
Reserved
-
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