- Add the VCOM custom device in VeriStand. Click Create VCOM Descriptor to open the RBSConfig tool.
- Right-click in the Datapool, then select New Network>>CAN or FlexRay Network>>Create single network to add the database file.
- Find the checksum signal in the Datapool, then right-click on it and select Copy2Config.
- Find the checksum signal in the Configuration, then left click it and choose Change to AutoSignal.
- In the drop-down menu of Auto Signal type, select ChecksumCCITT.
- CRCMask: Determine the data bytes that are used for the CRC calculation. For example, CRCMask 252(1111 1100 in binary) means that byte 2 to byte 7 of data bytes will be used for checksum calculation.
- UserBytesAfter: These bytes are used after the data bytes for the checksum calculation. Data ID can be filled here. The first byte is the low byte of Data ID and the second byte is the high byte of Data ID
Fill the above parameters as follows, then click Execute.
- Click the three points on the right side of ChecksumUserBytesAfter to edit the Data ID.
For example, the Data ID of this frame is 4957 (0x135D in hexadecimal). You should fill the ChecksumUserBytesAfter as the follows.
- Right-click on the database file in Configuration, then select Save as XML to save the configuration.
Note: If you want to protect the byte 8 to byte 20 to calculate the checksum, the CRCMask should be 2096896 (1 1111 1111 1111 0000 0000 in binary). There is a known issue that the control of CRCMask is limited to 255. If you fill a value greater than 255, an error will be triggered when button Execute is clicked.
A workaround is that you can fill a value less than 255. After the xml file is generated in step 7, you can open the xml file with Notepad/Notepad++. Then you can change this value to anything.
Before modification:
After modification:
