MV Report
MV Command (G-R)
Movement log for accident analysis and driving profile. Generates 100 accelerometer records, one every 80 ms: about 4 seconds before the command and about 4 seconds after it.
The accelerometer is read every 20 ms and every 4 reads make one record: one every 80 ms (12.5 Hz). Those 4 reads produce the three values of each axis: maximum, minimum and average.
Generate report
GMVbbcSee G Command for parameter details.
Response
RMVHHMISSDDMOYY.mmm X+XMAX+XMIN+XAVG Y+YMAX+YMIN+YAVG Z+ZMAX+ZMIN+ZAVG RRRVVVIIIEEExample, with the device still and lying flat:
RMV153045291224.500 X+0012-0008+0003 Y+0006-0004+0001 Z+0103+0097+0100 0B40451290A
// Z ≈ +100 = 1 g: that is gravity. X and Y, close to 0.
// Heading 0B4 = 180°, 45 km/h, inputs 129, event 0A.Report fields
| Field | Description |
|---|---|
| HHMISS | RTC time (HHMMSS) — comes first in the frame |
| DDMOYY | RTC date (DDMMAA) — comes after the time |
| .mmm | Milliseconds |
Accelerometer data
| Axis | Maximum | Minimum | Average |
|---|---|---|---|
| X | XMAX | XMIN | XAVG |
| Y | YMAX | YMIN | YAVG |
| Z | ZMAX | ZMIN | ZAVG |
The three values of each axis come from the 4 reads that make up the record: the highest, the lowest and the average of the four. All three share the same signed format (%+05d); there is no * prefix in the actual frame.
Raw values, in hundredths of g. The readings carry no mounting calibration (the one set with SCALINT): they are the axes of the accelerometer as soldered on the board, not the vehicle’s axes. The unit is 0.01 g (10 mg), so with the device still the axis that ends up vertical reads close to ±100 — that is gravity — with the sign depending on how it is mounted.
Dump calibration (RCAL)
Since firmware v1.09.28, before the first RMV the device sends an RCAL frame with the mounting calibration in force when the GMV fired, to the same destination. With it the platform can bring the raw values to the vehicle’s axes.
RCAL<en>,<roll>,<pitch>,<yaw>,<offX>,<offY>,<offZ>,<EE>,<origin>Example:
RCAL1,10.36,12.20,0.00,0.00,0.00,0.00,2A,1| Field | Description |
|---|---|
| en | 1 = calibration enabled, 0 = not |
| roll, pitch, yaw | Mounting angles, in degrees (2 decimals) |
| offX, offY, offZ | Offsets, in the same raw units as the RMV frames (0.01 g, 2 decimals) |
| EE | Event number (hex): the same one that closes every RMV of that dump |
| origin | 0 = no calibration (identity) · 1 = the rotation comes from roll/pitch/yaw · 2 = the device applies a legacy matrix that does not come from those angles: it cannot be reproduced from the RCAL |
To bring a sample to the vehicle’s axes (with origin = 1): subtract the offsets from the raw values and then rotate with Rz(yaw) · Ry(pitch) · Rx(roll). ISO 8855 convention: X forward, Y left, Z up; roll+ = right side down, pitch+ = nose down, yaw+ = left turn. Only the average of each axis (XAVG, YAVG, ZAVG) forms a vector: maximum and minimum are not rotated.
QCAL does not change: it still answers 7 fields. The dump’s RCAL is told apart because it carries 9. If a dump is already in progress, a new GMV is ignored and no RCAL is sent either.
Additional fields
| Field | Description |
|---|---|
| RRR | Heading in degrees, 3 hexadecimal digits (000 to 167, i.e. 0° to 359°) |
| VVV | Speed (km/h), 3 decimal digits |
| III | Digital inputs status, 3 decimal digits |
| EE | Event number (hex, 00-FF) |
The heading has a fixed 3 digits since firmware v1.09.28. Before, it came out with 2 hex digits up to 255° (FF) and with 3 from 256° to 359°, so the trailing field changed length with the direction. To read frames from any version, take the field from the end: EE (2) + III (3) + VVV (3), and whatever is left in front is the heading.
| Heading | Before v1.09.28 | Since v1.09.28 |
|---|---|---|
| 180° | B4 | 0B4 |
| 230° | E6 | 0E6 |
| 315° | 13B | 13B |
Record structure
Zero time = Moment of GMV command execution
| Period | Records | Description |
|---|---|---|
| ≈ −4 s | 50 | Those already in the buffer when the GMV arrived |
| ≈ +4 s | 50 | Those generated afterwards, live |
| Total | 100 | One record every 80 ms |
Associated triggers
4 groups of acceleration thresholds can be configured, providing 24 possible status flags for behavior analysis by axis.
See MVT Command
Applications
| Use | Description |
|---|---|
| Collision detection | Impact and accident analysis |
| Driving profile | Hard braking, accelerations |
| Forensic analysis | Event reconstruction |
| Driver scoring | Driving evaluation |