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

ENGINEERING TOMORROW
17.5.2

Sector CRC calculation

Upon having verified the correctness of the data in a given sector, the sector CRC shall be calculated and stored at the
CRC address. The CRC shall be calculated in accordance with CRC-CCITT polynomial, x
17.5.3

Example

Example for calculating the sector CRC for "Valve calibration data":
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 79. 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:
"5CFEA40197FF69001900". The CRC-CCITT result for this data is
The low byte (34h) shall be stored at P3183 and the high byte (F9h) at P3184.
17.5.4

Signature CRC calculation

Attention
As a step in safe parameterization of the PVED-CLS software, to ensure the correctness of the data in one or more
modified sectors it shall be signed. Signing off correctness is understood as it has been 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 78 for which PSACs are valid for the sectors.
•
The PSACs are fixed and cannot be changed for a given application software.
•
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 confidential code 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 the following steps:
168 | © Danfoss | August 2018
Description of parameter
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
Table 79
16
+ x
.
F934h
AQ00000211
12 5
+ x + 1 (0x1021).
Value Value
Dec Hex
-420 FE5Ch
420 01A4h
-105 FF97h
105 0069h
25 0019h
F934h