SET REFERENCES message - MD30

MD30 Interface Description
Document code
M212201EN
Revision
D
Language
English
Product
MD30
Document type
Technical description

SET REFERENCES is used for updating reference values during surface state calibration for plate reference and dry road reference (dry road coefficient).

Table 1. SET REFERENCES message

Message ID

 0x30

Data in request

Offset

 Data

Size in bytes
7

Surface type:

0 = Plate

1 = Road

 1

Data length

 1

Data in response

Offset

 Data

Size in bytes
9

Operation started / not started:

0 = Not started

1 = Started

 1
10 Status info 4
14 Error bits 4

Data length

 9
The ongoing reference setting does not affect the measurements, but the parameter update after data collection can interfere with the ongoing data transfer.

Reference setting is part of the following calibration steps:

  • Plate reference
  • Dry road reference

Reference setting consists of the following phases:

  1. Initiation
  2. Data collection
  3. Reference setting update

The phases are the same for both plate reference and dry road reference setting.

Figure 1. Reference setting as part of PLATE and ROAD reference calibration steps
The response Started to SET REFERENCES request indicates that the data collection has started, not that references have been updated.
During reference setting, check the progress with GET UNIT STATUS or SEND DATA message.

The updated reference setting values and corresponding parameters depend on the surface type.

Table 2. Reference setting parameters
Reference setting Vehicle Surface type Parameters
Plate reference At standstill PLATE 0x50, 0x51, 0x52
Dry road reference Moving ROAD 0x53, 0x54, 0x55

Initiation

SET REFERENCES initiates data collection for the reference values setting.

When the mobile sensor receives the SET REFERENCES message, it clears the 3 status info bits that indicate a previous failed reference setting, and parameter 0x56 is reset.

If initiation fails, the error condition is indicated with the status info and error bits in the response message. The status and error information list the conditions that were used for checking whether reference setting can be started.

For a list of error conditions, see the previous image. For details about the error conditions, see Status information and Error bits.

Data collection

Data collection takes a minimum of 25 seconds. If the road surface is not static during dry road reference, data collection can take longer.

Data collection is stopped if there are error conditions that prevent the start of reference setting. The reason is indicated in the status information, and stored in parameter 0x56. References are not updated.

Reference setting update

After collecting enough data, the sample quality is checked.

  • If the quality criteria for the sample is met, new reference setting values are calculated and references updated.

  • If the quality criteria is not met, references are not updated. Failure is indicated in the status info.

Example

After setting PLATE reference values using reference plate (calibration step 2), the reference values are set for dry road reference (calibration step 3):

  1. Client sends the SET REFERENCES message with the parameter ROAD.
  2. Initiation succeeds. The unit collects data for 25 seconds. The reference setting ongoing bit is set in status info bits.
  3. The client can check from the status info bits if data collection is ongoing. Both GET UNIT STATUS response and SEND DATA contain status info bits.
  4. All data is collected. Unit clears the reference setting ongoing bit. Dry road coefficients are updated and taken into use.