Implementing Checksum Algorithm E2E Profile 2 with NI VCOM RBS Descriptor Tool

NI-VCOM defines many common checksum algorithms in the RBS Descriptor tool. The users can implement checksum easily, compared to the custom interface way introduced in Using NI-VCOM Toolkit to Define the Custom Checksum for CAN Application. This article will introduce how to configure E2E Profile 2 with the RBS Descriptor tool.

1. Add the VCOM custom device in VeriStand. Click Create VCOM Descriptor to open the RBSConfig tool.
2. Right-click in the Datapool, then select New Network>>CAN or FlexRay Network>>Create single network to add the database file.
3. Find the checksum signal in the Datapool, then right-click on it and select Copy2Config.

4. Find the checksum signal in the Configuration menu, then click it and choose Change to AutoSignal.

5. In the drop-down menu of Auto Signal type, select ChecksumUserJ1850.

• CRCMask: Determine the data bytes that are used for the CRC calculation. For example, CRCMask 254(1111 1110 in binary) means that byte 1 to byte 7 of data bytes will be used for checksum calculation.
• Initial Value: CRC initial value. Default value is 255. For E2E Profile 2, it should be 255.
• FinalXORValue: XOR value at the end of the CRC algorithm. Default value is 255. For E2E Profile 2, it should be 255.
• UserByteBefore: These bytes are used before the data bytes for the checksum calculation. Leave it empty for E2E Profile 2.
• UserByteAfter: These bytes are used after the data bytes for the checksum calculation. Data ID list of E2E Profile 2 can be filled here.

      Fill the above parameters as follows, then click Execute.

6. Click the checksum signal in Auto Signals. In the Details, delete the elements in ChecksumUserBytesBefore by click the three points on the right side, then clicking Remove.

7. Click the three points on the right side of ChecksumUserBytesAfter to edit the Data ID list.

For example, the Data ID list of this frame is [11, 22, 33, 44, 55, 66, 77, 88, 99, 110, 120, 130, 140, 150, 160, 170]. You should fill the ChecksumUserBytesAfter as follows.

8. Right-click on the database file in Configuration, then select Save as XML to save the configuration.

Additional Information

There is a known issue about the value of CRCMask. A workaround is provided, please refer to Implementing Checksum Algorithm E2E Profile 5 with NI VCOM RBS Descriptor Tool.