DIS Sensors CAN Podręcznik użytkownika - Strona 7

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CAN User Manual

Inclination Safety Sensor

(Type D) V2.0

8.4 Peak Suppression Filter:

Two Peak Suppression Filters (PSF) are implemented to reduce unwanted disturbances in the inclination

measurement caused by acceleration peaks.

Filter principle: as inclination normally changes relative slow, a sudden peak in the inclination signal indicates an

acceleration peak instead of a real inclination angle change. In this case, the filter can make the sensor ignore

this peak for a certain time.

PSF in the redundancy compare chain (object 4007h):

The redundancy compare chain checks the difference between the two redundant MEMS chips. The filter helps

to prevent for false safety alarms.

PSF in the inclination output chain (object 4008h):

The filter in the output chain makes the inclination output more stable and more realistic

PSF can be adjusted with 2 parameters:

•

Angle (°): This parameter sets the threshold for the peak. Only peaks above this threshold will be

filtered. Setting this angle parameter to 0° will disable the PSF

•

Time (ms): After the peak suppression filter becomes active, it will hold the inclination signal for a

certain period of time, set by this parameter.

Default values for Object 4007h: on, 3°, 40ms

Default values for Object 4008h: on, 9°, 50ms

8.5 Pre-set/zero adjustment:

To eliminate mechanical offsets a pre-set/ zero value can be added. This can be done with the pre-set/zero

adjustment method, so introducing a permanent offset on the output of the sensor (centre point = middle of

measuring range). The current position will be regarded as the new pre-set/zero position. This can be done

limited to 100.000x. (The value is written in EEPROM. The write actions for EEPROM is limited to 100.000x)

Via CAN object 300Fh (see sensor specific part) the centering/zeroing can be done for each axis separate or for

both axis at the same time. Status information of the result is available from the same object 300Fh

Since the offset has direct influence on the output angle, the pre-set/zero value is protected with a CRC code.

This CRC code must be set via object 63FFh. When the CRC code is written it must be validated with object 63FE

sub id 0 writing data A5h.

The polynomial of the CRC code is:

Table 1 Object fields for zero value (pre-set) CRC calculation

Order

Index

Sub index

6200h

00h

01h

02h

For CRC calculation a PC tool is developed and can be found on the DIS web site

We have implemented two different CRC-calculations. Please check your firmware version number first, and then

select the right Firmware version when using the PC-tool.

A CRC code is also oblige for SRDO1 messages. For detailed information about generating see EN 50325-5. This

CRC code can also be calculated with the same PC tool.

( ) =

Value

Highest sub index supported

Sub index number

Safety slope longitudinal offset (pre-set) value

Sub index number

Safety slope lateral offset(pre-set) value

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