Downloading and Analyzing Data Logs in Mission Planner

Dataflash logs are stored on the Pixhawk (or APM2.x) onboard dataflash memory and can be download after a flight. On Plane and Rover dataflash logs are created soon after start-up. On Copter they are created after you first arm the copter. This topic explains how to configure and access Dataflash logs.


Telemetry logs (also known as “tlogs”) collect similar information to dataflash logs (see Diagnosing problems using Logs for more information).

Automatic Analysis of logs


Mission Planner: Start LogAnalysis

The simplest analysis is to generate a basic automated report that will highlight common problem areas. For that, click on “Log Analysis” and select a log that you’ve already saved to the MissionPlanner/logs directory. They will be in folders named after the vehicle type, such as QUADCOPTER or ROVER. Once you pick the log you want, it will generate a report that looks like this:


Manually review a log

For more detailed analysis, click on “Review a Log” and select a log that you’ve already saved to the MissionPlanner/logs directory. Once again, they will be in folders named after the vehicle type, such as QUADCOPTER or ROVER. Once you pick the log you want, you will get charts such as the below. The basic format of the dataflash is:

  • Line numbers appear on the very left side of the viewer
  • Software version and board type appear at the top
  • FMT messages are next which tell the mission planner the column headers for each message type
  • PARM rows which show each parameter (in the order in which they appear in the eeprom) along with their value at the beginning of the flight
  • Flight data messages including GPS, IMU, etc.

Graph any flight data by first clicking on the appropriate row, you should see the column headers update appropriately. Next find the column you wish to graph, click on it and then push the “Graph this data” button. In the example above the ATT’s Roll-In and Roll data have been graphed. The mouse’s scroll wheel can be used to zoom in or out. You may also select an area of the graph to zoom in on it. Zoom out by right-mouse-button clicking and selecting “Set Scale to Default”. Here’s a mini tutorial on using this feature. You may also filter on just the first column (the flight data message type) by clicking on the first column and selecting the message type from the drop-down. This is very useful especially for viewing the different flight modes (called “MODE” messages) used during the mission. Click the first column again but press “Cancel” to clear the filter.


Setting what data you want recorded

The LOG_BITMASK parameter controls what message types are recorded in the dataflash. Recent versions of the mission planner and ardupilot allow individual messages to be enabled/disabled from the MP’s Config/Tuning, Standard Params screen.


Earlier versions of MP/ardupilot allow selecting the message using a drop-down as shown below.


Message Details (Copter specific)

ATT (attitude information):

RollIn The pilot’s desired roll angle in centi-degrees (roll left is negative, right is positive)
Roll The vehicle’s actual roll in centi-degrees (roll left is negative, right is positive)
PitchIn The pilot’s desired pitch angle in centi-degrees (pitch forward is negative, pitch back is positive)
Pitch The vehicle’s actual pitch angle in centi-degrees (roll left is negative, right is positive)
YawIn Tthe pilot’s desired yaw rate as a number from -4500 ~ 4500 (not in deg/sec, clockwise is positive)
Yaw The vehicles actual heading in centi-degrees with 0 = north
NavYaw The desired heading in centi-degrees

ATUN (auto tune overview):

  Axis: 0 = Roll, 1 = Pitch
TuneStep 0 = Returning towards Level (before or after a test), 1 = Testing (i.e. performing a twitch to test response), 2 = Updating gains (twitch completed and gains adjusted)
RateMin Minimum recorded rate during this test
RateMax Maximum recorded rate during this test
RPGain Rate P gain value being tested
RDGain Rate D gain value being tested
SPGain Stabilize P gain being tested

ATDE (auto tune step details):

Angle Angle of the copter in centi-degrees for the axis being testedx
Rate Rate of rotation of the copter for the axis being tested

CAM (time and position when camera shutter was activated):

GPSTime The GPS reported time since epoch in milliseconds
Lat The accelerometer + GPS latitude estimate
Lng The accelerometer + GPS longitude estimate
Alt The accelerometer + barometer estimated altitude in cm above ground
Roll The vehicle roll angle in centi-degrees
Pitch The vehicle pitch angle in centi-degrees
Yaw The vehicle’s heading in centi-degrees

CMD (commands received from the ground station or executed as part of a mission):

CTot The total number of commands in the mission
CNum This command’s number in the mission (0 is always home, 1 is the first command, etc)
CId The mavlink message id
Copt The option parameter (used for many different purposes)
Prm1 The command’s parameter (used for many different purposes)
Alt The command’s altitude in meters
Lat The command’s latitude position
Lng The command’s longitude position

COMPASS (raw compass, offset and compassmot compensation values):

Field Description
MagX, MagY. MagZ Raw magnetic field values for x, y and z axis
OfsX, OfsY, OfsZ Raw magnetic offsets (will only change if COMPASS_LEARN parameter is 1)
MOfsX, MOfsY, MOfsZ Compassmot compensation for throttle or current

CURRENT (battery voltage, current and board voltage information):

Thr Pilot input throttle from 0 ~ 1000
ThrInt Integrated throttle (i.e. sum of total throttle output for this flight)
Volt Battery voltage in volts \* 100
Curr Current drawn from the battery in amps \* 100
Vcc Board voltage
CurrTot Total current drawn from battery

CTUN (throttle and altitude information):

ThrIn The pilot's throttle in as a number from 0 to 1000
SonAlt The altitude above ground according to the sonar
BarAlt The altitude above ground according to the barometer
WPAlt The desired altitude while in AltHold, Loiter, RTL or Auto flight modes
NavThr Not used
AngBst Throttle increase (from 0 ~ 1000) as a result of the copter leaning over (automatically added to all pilot and autopilot throttle to reduce altitude loss while leaning)
CRate Accelerometer + baro climb rate estimate in cm/s
ThrOut Final throttle output sent to the motors (from 0 ~ 1000). Normally equal to ThrIn+AngBst while in stabilize mode.
DCRate Pilot desired climb rate in cm/s

D32, DU32 (single data values which are either signed 32bit integers or unsigned 32bit integers):

id Identification number for the variable. There are only two possible values:
  • 7 = bit mask of internal state. The meaning of individual bits can be found in `Copter.cpps’s definition of the ap structure `__./
  • 9 = simple mode's initial heading in centi-degrees

EKF (Extended Kalman Filter):

Log information here (Dev Wiki). Overview here.

ERR (an error message):

SubSystem and Error codes listed below

1: Main (never used)
2: Radio
  • ECode 1: “Late Frame” which means the APM’s onboard ppm encoder did not provide an update for at least 2 seconds
  • ECode 0: error resolved which means the ppm encoder started providing data again
3: Compass
  • ECode 1: the compass failed to initialise (likely a hardware issue)
  • ECode 2: failure while trying to read a single value from the compass (probably a hardware issue)
  • ECode 0: above errors resolved
4: Optical flow Ecode 1: failed to initialise (likely a hardware issue)
5: Throttle failsafe
  • ECode 1: throttle dropped below FS_THR_VALUE meaning likely loss of contact between RX/TX
  • ECode 0: above error resolve meaning RX/TX contact likely restored
6: Battery failsafe ECode 1: battery voltage dropped below LOW_VOLT or total battery capacity used exceeded BATT_CAPACITY
7: GPS failsafe
  • ECode 1: GPS lock lost for at least 5 seconds
  • ECode 0: GPS lock restored
8: GCS (Ground station) failsafe
  • ECode 1: updates from ground station joystick lost for at least 5 seconds
  • ECode 0: updates from ground station restored
9: Fence
  • ECode 1: altitude fence breached
  • ECode 2: circular fence breached
  • ECode 3: both altitude and circular fences breached
  • ECode 0: vehicle is back within the fences
10: Flight Mode ECode 0 ~ 17: the vehicle was unable to enter the desired flight mode (0=Stabilize, 1=Acro, 2=AltHold, 3=Auto, 4=Guided, 5=Loiter, 6=RTL, 7=Circle, 8=Position, 9=Land, 10=OF_Loiter, 11=Drift, 13=Sport, 14=Flip, 15=AutoTune, 16=PosHold, 17=Brake)
11: GPS
  • ECode 2: GPS Glitch
  • ECode 0: GPS Glitch cleared
12: Crash Check ECode 1: Crash detected

EV: (an event number). The full list of possible events can be found in defines.h but the most common are:

10 Armed
11 Disarmed
15 Auto Armed (pilot has raised throttle above zero and autopilot is free to take control of throttle)
16 TakeOff
18 Land Complete
25 Set Home (home location coordinates have been capture)


Status 0 = no GPS, 1 = GPS but no fix, 2 = GPS with 2D fix, 3 = GPS with 3D fix
Time The GPS reported time since epoch in milliseconds
NSats The number of satellites current being used
`HDop `__: A measure of gps precision (1.5 is good, >2.0 is not so good)
Lat Lattitude according to the GPS
Lng Longitude according to the GPS
RelAlt Accelerometer + Baro altitude in meters
Alt GPS reported altitude (not used by the flight controller)
SPD Horizontal ground speed in m/s
GCrs Ground course in degrees (0 = north)

IMU (accelerometer and gyro information):

GyrX, GyrY, GyrZ The raw gyro rotation rates in degrees/second
AccX, AccY, AccZ The raw accelerometer values in m/s/s

Mode (flight mode):

Mode The flight mode displayed as a string (i.e. STABILIZE, LOITER, etc)
ThrCrs Throttle cruise (from 0 ~ 1000) which is the autopilot's best guess as to what throttle is required to maintain a stable hover

NTUN (navigation information):

WPDst Distance to the next waypoint (or loiter target) in cm. Only updated while in Loiter, RTL, Auto flight modes.
WPBrg Bearing to the next waypoint in degrees
PErX Distance to intermediate target between copter and the next waypoint in the latitude direction
PErY Distance to intermediate target between copter and the next waypoint in the longitude direction
DVelX Desired velocity in cm/s in the latitude direction
DVelY Desired velocity in cm/s in the longitude direction
VelX Actual accelerometer + gps velocity estimate in the latitude direction
VelY Actual accelerometer + gps velocity estimate in the longitude direction
DAcX Desired acceleration in cm/s/s in the latitude direction
DAcY Desired acceleration in cm/s/s in the longitude direction
DRol Desired roll angle in centi-degrees
DPit Desired pitch angle in centi-degrees

PM (performance monitoring):

RenCnt DCM renormalization count - a high number may indicate problems in DCM (extremely rare)
RenBlw DCM renormalization blow-up count - how many times DCM had to completely rebuild the DCM matrix since the last PM. Normally innocuous but a number that constantly grows may be an indication that DCM is having troubles calculating the attitude (extremely rare)
FixCnt The number of GPS fixes received since the last PM message was received (it's hard to imagine how this would be useful)
NLon Number of long running main loops (i.e. loops that take more than 5% longer than the 10ms they should)
NLoop The total number of loops since the last PM message was displayed. This allows you to calculate the percentage of slow running loops (which should never be higher than 15%). Note that the value will depend on the autopilot clock speed.
MaxT The maximum time that any loop took since the last PM message. This should be close to 10,000 but will be up to 6,000,000 during the interval where the motors are armed
PMT A number that increments each time a heart beat is received from the ground station
I2CErr The number of I2C errors since the last PM message. Any I2C errors may indicate a problem on the I2C bus which may in turn slow down the main loop and cause performance problems.

RCOUT (pwm output to individual RC outputs):

RC1, RC2, etc : pwm command sent from flight controller to the esc/motor/RC output


When you download the dataflash log files from the APM/PX4 it will automatically create a KMZ file (file with extension .kmz). This file can be opened with Google Earth (just double click the file) to view your flight in Google Earth. Please see the instructions on the Telemetry Logs Page for additional details.

Video tutorials