Example; Signature Crc Calculation - Danfoss PVED-CLS User Manual

ENGINEERING TOMORROW

16.4.3 Example

Name
Max Spool Position,
Left
Max Spool Position,
Right
Closed loop dead-
band edge, Left
Closed loop dead-
band edge, Right
Open loop dead-
band edge offset
Sector CRC
The data that is target for the CRC calculation is given in Table 72. The last byte that shall be included in the CRC
calculation is P3171 which holds the high byte of the Offset Dead-band OL parameter. Unused byte may be set to 0.
To calculate the sector CRC, the data is first rearranged into little endian format as follows:
5CFEA401B0FF50001900
The low byte (34h) shall be stored at P3183 and the high byte (F9h) at P3184.

16.4.4 Signature CRC calculation

Attention
As a step in safe parameterization of the PVED-CLS software, the system integrator shall sign for the correctness of the data
in one or more modified sectors. Signing off correctness is understood as the system integrator has verified that all values
in a sector are correct. This is valid for the entire parameter sector.
The PVED-CLS software checks the sector data integrity (sector CRC) and if the sector data is approved (Signature CRC) as
an instance of the power-up self-test. The PVED-CLS enters the safe state with a specific CAN diagnostic trouble code if one
of the checks fail.
Important

Two PSAC (Parameter Sector Approval Code) levels exists; OEM and Dealer.

See Table 71 for which PSACs are valid for the sectors.

The PSACs are fixed and cannot be changed for a given application software.

The system integrator shall contact Danfoss Product Application Engineering for the relevant PSACs.

It is the responsibility of the OEM/system integrator to keep the PSACs secret for unauthorized personnel.

The PSACs shall be treated as credit card pin codes and thus not displayed directly on a service tool page.

Disclosing the PSACs may lead to loss of safety integrity of the product.
The data in a particular sector is approved by system integrator by the following steps:
1. Verify the changes to the sector by comparison of desired data to read-back inverted data.
2. Calculate the signature CRC as CRC-CCITT (sector data + PSAC). See example.
Valve calibration data
P3162 S16 Spool left most position
P3164 S16 Spool right most position
P3166 S16 Spool closed loop dead-band edge,
Left
P3168 S16 Spool closed loop dead-band edge,
Right
P3170 S16 Spool open loop dead-band offset
P3183 U16 CRC value for the valve calibration
sector
he CRC-CCITT result for this data is
Description of parameter
Table 72
.
F934h
Value Value
Dec Hex
-420 FE5Ch
420 01A4h
-105 FF97h
105 0069h
25 0019h
F934h