Work with MDF Events
This example shows how to read events from MDF files and filter data using events.
View All Events in MDF File
View metadata and events of an MDF file using mdfInfo by specifying the file name.
fileInfo = mdfInfo("VehicleDataWithEvents.mf4")fileInfo =
MDFInfo with properties:
File Details
Name: "VehicleDataWithEvents.mf4"
Path: "C:\Users\komar\OneDrive - MathWorks\Documents\MATLAB\ExampleManager\komar.Bdoc.DOC\vnt-ex41269135\VehicleDataWithEvents.mf4"
Author: ""
Department: ""
Project: ""
Subject: ""
Comment: "Example file demonstrating workflows of reading events."
Version: "4.10"
InitialTimestamp: 2024-04-23 18:35:45.000000000
Creator Details
ProgramIdentifier: "MDF4Lib"
CreatorVendorName: ""
CreatorToolName: ""
CreatorToolVersion: "1.0"
CreatorUserName: ""
CreatorComment: "created"
File Contents
Attachment: [0×7 table]
ChannelGroupCount: 2
Event: [8×8 eventtable]
The Event property contains an eventtable of all the events within the MDF file.
fileEvents = fileInfo.Event
fileEvents = 8×8 eventtable
Event Labels Variable: Name
Event Lengths Variable: <instantaneous>
Time Name Comment Type Cause ScopeType GroupNumber RangeType LinkAddress
________ ________________ ________________________________________________________ __________________ ______ ____________ ___________ _________ ___________
0 sec "USER COMMENT" "Logging Vehicle Data 12/24/23" Marker User File NaN Point ""
1 sec "REC BEGIN" "Recording has started successfully." Recording Tool File NaN Begin "0x1C80"
1.2 sec "REC INTERRUPT" "Recording was interrupted." RecordingInterrupt Script ChannelGroup 1 Point ""
8.5 sec "USER REC BEGIN" "User-initiated subrecording start." Recording User ChannelGroup 1 Begin "0x1EC8"
10 sec "TIME TRIGGER" "Time min threshold trigger of 10 seconds has been hit." Trigger Script ChannelGroup 2 Point ""
11.5 sec "USER REC END" "User-initiated subrecording end." Recording User ChannelGroup 1 End "0x1EC8"
14.1 sec "RPM TRIGGER" "RPM max threshold trigger of 1500 has been hit." Trigger Script ChannelGroup 1 Point ""
15 sec "REC END" "Recording has stopped successfully." Recording Tool File NaN End "0x1C80"
Each event has a timestamp and 8 metadata values.
The
ScopeTypevalue represents whether the event applies to a particular channel group or the entire file.The
GroupNumbervalue represents the particular channel group the event is scoped to.Events can occur either at a point in time or over a range of time. The
RangeTypevalue represents if the event occurs at a point of time, marks the beginning of a range, or marks the end of a range.The
LinkAddressvalue is used to link corresponding range events. A pair of beginning and ending range events share the sameLinkAddressvalue, and that value represents the address of the beginning event.
Read All Data and Events from MDF File
The easiest way to read all data and events from an MDF file is to call the mdfRead function with just the file name. Each timetable represents data read from the corresponding channel group. Each timetable contains an eventtable which represents file level events and channel group level events scoped to the corresponding channel group.
data = mdfRead("VehicleDataWithEvents.mf4")data=2×1 cell array
{160×3 timetable}
{ 16×3 timetable}
data{1}ans=160×3 timetable
t EngineRPM Throttle OutputTorque
_______ _________ ________ ____________
USER COMMENT 0 sec 41 7 34
0.1 sec 10 9.5 25
0.2 sec 98 9 14
0.3 sec 94 6.5 48
0.4 sec 121 9 15
0.5 sec 141 7.5 47
0.6 sec 87 9 47
0.7 sec 74 5.5 10
0.8 sec 172 6 29
0.9 sec 106 12.5 54
REC BEGIN 1 sec 147 11 31
1.1 sec 148 14.5 23
REC INTERRUPT 1.2 sec 187 15 47
1.3 sec 224 9.5 24
1.4 sec 162 10 37
1.5 sec 214 8.5 26
⋮
Retrieve the events attached to the timetable by accessing its Events property.
chanGrp1Events = data{1}.Properties.EventschanGrp1Events = 7×8 eventtable
Event Labels Variable: Name
Event Lengths Variable: <instantaneous>
Time Name Comment Type Cause ScopeType GroupNumber RangeType LinkAddress
________ ________________ _________________________________________________ __________________ ______ ____________ ___________ _________ ___________
0 sec "USER COMMENT" "Logging Vehicle Data 12/24/23" Marker User File NaN Point ""
1 sec "REC BEGIN" "Recording has started successfully." Recording Tool File NaN Begin "0x1C80"
1.2 sec "REC INTERRUPT" "Recording was interrupted." RecordingInterrupt Script ChannelGroup 1 Point ""
8.5 sec "USER REC BEGIN" "User-initiated subrecording start." Recording User ChannelGroup 1 Begin "0x1EC8"
11.5 sec "USER REC END" "User-initiated subrecording end." Recording User ChannelGroup 1 End "0x1EC8"
14.1 sec "RPM TRIGGER" "RPM max threshold trigger of 1500 has been hit." Trigger Script ChannelGroup 1 Point ""
15 sec "REC END" "Recording has stopped successfully." Recording Tool File NaN End "0x1C80"
data{2}ans=16×3 timetable
t VehicleSpeed Brake Gear
______ ____________ _____ ____
USER COMMENT 0 sec 82 0 1
REC BEGIN 1 sec 97 1 2
2 sec 45 1 1
3 sec 58 1 0
4 sec 42 0 3
5 sec 146 1 1
6 sec 155 1 0
7 sec 130 0 0
8 sec 110 0 3
9 sec 161 1 3
TIME TRIGGER 10 sec 153 0 2
11 sec 134 0 3
12 sec 160 1 2
13 sec 159 0 1
14 sec 198 0 1
REC END 15 sec 157 1 0
chanGrp2Events = data{2}.Properties.EventschanGrp2Events = 4×8 eventtable
Event Labels Variable: Name
Event Lengths Variable: <instantaneous>
Time Name Comment Type Cause ScopeType GroupNumber RangeType LinkAddress
______ ______________ ________________________________________________________ _________ ______ ____________ ___________ _________ ___________
0 sec "USER COMMENT" "Logging Vehicle Data 12/24/23" Marker User File NaN Point ""
1 sec "REC BEGIN" "Recording has started successfully." Recording Tool File NaN Begin "0x1C80"
10 sec "TIME TRIGGER" "Time min threshold trigger of 10 seconds has been hit." Trigger Script ChannelGroup 2 Point ""
15 sec "REC END" "Recording has stopped successfully." Recording Tool File NaN End "0x1C80"
Filter Data Using Events
To filter MDF data based on events, use an eventfilter. Create a subset of channel group 1 data containing samples that share a timestamp with an event.
EF = eventfilter(data{1})EF =
eventfilter with no constraints and no selected variables
<unconstrained>
VariableNames: Time, Name, Comment, Type, Cause, ScopeType, GroupNumber, RangeType, LinkAddress
dataFilteredToEventTimestamps = data{1}(EF, :)dataFilteredToEventTimestamps=7×3 timetable
t EngineRPM Throttle OutputTorque
________ _________ ________ ____________
USER COMMENT 0 sec 41 7 34
REC BEGIN 1 sec 147 11 31
REC INTERRUPT 1.2 sec 187 15 47
USER REC BEGIN 8.5 sec 896 44.5 121
USER REC END 11.5 sec 1158 59.5 160
RPM TRIGGER 14.1 sec 1503 75.5 172
REC END 15 sec 1519 80 176
Create a subset of channel group 1 data containing samples between the user-initiated recording start event and the user-initiated recording end event.
TR = timerange(EF.Name == "USER REC BEGIN", EF.Name == "USER REC END")
TR = timetable timerange subscript: Select timetable rows with event times in the half-open interval: Starting at, including: Name == "USER REC BEGIN" Ending at, but excluding: Name == "USER REC END" See Select Times in Timetable.
dataFilteredToUserRecEventTimeRange = data{1}(TR, :)dataFilteredToUserRecEventTimeRange=30×3 timetable
t EngineRPM Throttle OutputTorque
_______ _________ ________ ____________
USER REC BEGIN 8.5 sec 896 44.5 121
8.6 sec 935 46 105
8.7 sec 912 47.5 103
8.8 sec 961 52 110
8.9 sec 941 45.5 138
9 sec 957 51 132
9.1 sec 999 50.5 103
9.2 sec 920 46 95
9.3 sec 999 47.5 131
9.4 sec 941 56 99
9.5 sec 973 49.5 130
9.6 sec 1042 53 134
9.7 sec 996 55.5 104
9.8 sec 1012 51 117
9.9 sec 1044 50.5 138
10 sec 1076 59 118
⋮
Visualize Data with Events
Use stackedplot to visualize MDF data with events marked as vertical lines.
stackedplot(data{1})
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