Issue with number of bytes received

[BhaktiK]

When we send any command e.g. Connect(0x01) to ECU we get 8 bytes of response. However in my case ECU sends 3 bytes of response to Erase(0x10) command. This data follows CCP standard. Labview waits for 8 bytes of data and even if ECU sends positive response Labview shows error of 'Received Invalid Command counter' Error code -301082. Is there any way so that Labview will accepts the data coming?

[Gibson]

the CCP specification says something different
see CCP 2.1 spec v. 18-feb-99, chapter 7.2.2

The data lenght code of the CRM must always be 8. Unused data bytes, marked as „don’t
care„ in the command descriptions, may have arbitrary values.

So it looks like the ECU does not follow the convention to respond with a 8 byte CRM frame.
Is there a chance that you can change the ECU CCP stack accordingly?

- Roland

[Gibson]

the CCP specification says something different
see CCP 2.1 spec v. 18-feb-99, chapter 7.2.2

The data lenght code of the CRM must always be 8. Unused data bytes, marked as „don’t
care„ in the command descriptions, may have arbitrary values.

So it looks like the ECU does not follow the convention to respond with a 8 byte CRM frame.
Is there a chance that you can change the ECU CCP stack accordingly?

- Roland

[BhaktiK]

Thanks for your reply.

I don't have any access to change program in ECU.

Even if CRM must be of 8 bytes length,unused bytes are marked as 'don't care'. ECU is sending only the required number of bytes.

Is there any way where in we can receive the frame in Labview and ignore the 'Don't Care' bytes. This will help to communicate with any type of ECU which has CCP protocol.

[Vaibhav_Vashisht]

Hi,

Is it possible that you check the number of bytes received each time you acquire data and then append data to the Don't Care Bytes to convert your output to 8 bytes?

Regards,

Vaibhav.

[Ujjval Shah]

Hi BhaktiK,

Are you using CAN to communicate with protocol or NI ECU Measurement and Calibration Toolkit for LabVIEW? If you are using the toolkit i doubt you can do anything about it.

However if you are using CAN to communicate then you can manually configure for how many bytes LabVIEW has to wait for a complete command.

You can do this in MAX by going to that channel under Data Neighbourhood and configuring the properties for it.

Hope this helps.

Regards,

Ujjval Shah

Message Edited by Ujjval Shah on 08-27-2009 09:47 AM

[Gibson]

We have looked into the ECUMC toolkit code and may see a chance to fix the behaviour on our side for the next release.

If you need further informations please send an email to our product support engineer

canpse@ni.com

Thanks