B&R Industries X20 System, User Manual

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X20 system modules • Counter modules • X20DC4395
888 X20 system User's Manual 3.10
4.11.17.12.9 Time measurement function
The module has a time measurement function for each I/O channel. It can be configured separately for rising and
falling edges on each channel.
A starting edge can be configured for each time measurement function. When a configured starting edge occurs,
the value of the internal timer is saved in a FIFO. This FIFO holds up to 16 elements. When the actual trigger edge
occurs, the difference in time between the starting edge and the triggered edge is copied to the respective register.
Bits 8 to 11 "Previous start edge" of the 4.11.17.12.9.2 "CfO_EdgeTimeFallingMode" and 4.11.17.12.9.3
"CfO_EdgeTimeRisingMode" registers can be used to define which detected starting edge from the FIFO should
be used to calculate the difference. Additionally, when the trigger edge occurs, the counter clocked internally us-
ing bits 12 to 15 "Time measurement resolution are copied to the 4.11.17.12.9.10 "TimeStampFallingCH" and
4.11.17.12.9.11 "TimeStampRisingCH" registers.
Information:
The time measurement function is an extension of edge detection, so all of the channels used must
be configured there.
4.11.17.12.9.1 Enable time measurement function
Name:
CfO_EdgeTimeglobalenable
This register enables/disables the time measurement function for the entire module.
Data type Value
USINT See bit structure.
Bit structure:
Bit Description Value Information
0 Disabled for entire module 0 Time measurement function
1 Enabled for entire module
1 - 7 Reserved -
4.11.17.12.9.2 Configure time measurement function for the falling edge
Name:
CfO_EdgeTimeFallingMode01 to CfO_EdgeTimeFallingMode08
These registers can be used to configure the time measurement function for the falling edge of the respective
channel.
Data type Value
UINT See bit structure.
Bit structure:
Bit Description Value Information
0 Channel 1
...
0 - 3 Selects the channel for the starting edge
7 Channel 8
0 The falling edge of the channel configured in bits 0 to 3 serves
as the starting edge.
4 Selects the edge for the starting edge
1 The rising edge of the channel configured in bits 0 to 3 serves
as the starting edge.
5 - 6 Reserved -
0 Triggered
1)
7 Trigger
1 Continuous
2)
8 - 11 Previous start edge 0 to 15 The value determines which entry in the starting edge FIFO
should be used to calculate the time difference.
0 8 Mhz
1 4 Mhz
2 2 Mhz
3 1 Mhz
4 500 kHz
5 250 kHz
6 125 kHz
12 - 15 Time measurement resolution
7 625 kHz
1) The time measurement is triggered by the corresponding bit in the 4.11.17.12.9.5 "TriggerRisingCH" register.
2) Time measurement runs continuously and is triggered at every edge.