Documentation is incomplete regarding how DTC are reported

[ep081106]

i used the following code to read the DTC:
with Client(conn, request_timeout=10) as client:
DTC_list = client.get_dtc_by_status_mask(status_mask)
print("DTC list:", DTC_list)

but i didn't get the DTC code, i got :
DTC list :<PositiveResponse:[ReadDTCInformation]-61 data bytes at 0x0322ff0>;

could you please tell me how can i get the DTC code?

[pylessard]

Agree that the documentation is incomplete regarding how the DTC are reported.
In your case, DTCs are in response.service_data.dtcs which is an array of DTC object.

Example

response.service_data.dtcs[0].id
response.service_data.dtcs[0].status
response.service_data.dtcs[0].severity

For now, your best source of information will be the unit tests themselves. Each subfunction has a TestSuite associated.

python-udsoncan/test/client/test_read_dtc_information.py

Lines 126 to 139 in 7c37ed8

	def client_assert_response(self, response, expect_all_zero_third_dtc=False):
	self.assertEqual(response.service_data.status_availability.get_byte_as_int(), 0xFB)
	number_of_dtc = 3 if expect_all_zero_third_dtc else 2
	self.assertEqual(len(response.service_data.dtcs), number_of_dtc)
	self.assertEqual(response.service_data.dtc_count, number_of_dtc)
	self.assertEqual(response.service_data.dtcs[0].id, 0x123456)
	self.assertEqual(response.service_data.dtcs[0].status.get_byte_as_int(), 0x20)
	self.assertEqual(response.service_data.dtcs[0].severity.get_byte_as_int(), 0x00)
	self.assertEqual(response.service_data.dtcs[1].id, 0x123457)
	self.assertEqual(response.service_data.dtcs[1].status.get_byte_as_int(), 0x60)
	self.assertEqual(response.service_data.dtcs[1].severity.get_byte_as_int(), 0x00)

I will try to update the documentation on the short term to make this clearer.

[ep081106]

Sorry for trouble you again！
Based on your suggestions，My friend and me try our best to find the DTC list, but still cannot get them, maybe our methods are wrong.
we tried to use "print(response.service_data.dtcs)" to get the DTC list, but got the wrong message "name 'resonse' is not defined".
And we tried copy the code in "python-udsoncan/test/client/test_read_dtc_information.py" Lines 126 to 139, still worng.

could you please give us an example to find it? we have no any method now. thanks!
`
UDSdemo_0704.zip

`

[pylessard]

The error is simple. As it says, response doesn't exist. That's because in my example, response is what you get from get_dtc_by_status_mask(). Every client function return a Response object. In that response you have:

• response.data : The raw data of the response
• response.service_data : The data interpreted by the right service parser.

In the below image, you don't use the right variable.

Just do:

response = client.get_dtc_by_status_mask(status_mask)
print(response.service_data.dtcs)        # Will print an array of object
for dtc in response.service_data.dtcs:
    print("DTC : %06X" % dtc.id )         # Print the DTC number

[ep081106]

could you please add "how to read the DTC sanpshot" also？ thanks！

[pylessard]

Hi, I will leave this issue opened. Documentation needs to be updated.

Thanks for pointing the issue

[jwdsoft]

Can you please tell me which hardware could I use in order to use this library ?
also I want to know if this library support trucks also ? since I will test it on a truck ECU
(I did't want to open an issue about these question since they are not issues)

[pylessard]

Hi @jwdsoft , I think your question deserve a new issue. I've created #44 to help answers.
Honnestly, I personnaly am not aware of what commercial platform uses it. I know about some electric buses and delivery trucks; UDS is trending in the world of EV.

Heavy trucks mostly uses J1939. Hopefully, #44 will gather some useful informations to answer this.

[ep081106]

hi pylessard, i try to read the DID by using ReadDataByIdentifier, but i get the error: "ConfigError – If didlist parameter or response contains a DID not defined in didconfig";
form the document, i found the example for DidConfig:

Example of DidConfig
.. code-block:: python
didconfig = {
0x1111 : '<H', # Strings are processed by struct.unpack
0x2222 : MyCustomDidCodec, # Inherits the udsoncan.DidCodec,
0x3333 : MyCustomDidCodec(param1='hello') # Instance can also be provided
0x4444 : dict(key1='val1', key2='val2', codec=MyCustomDidCodec} # If dict is given, a key named "codec" will be searched for
}

i think the DidConfig shall be added in "udsoncan/init.py/class DidCodec", but i still don't know how to add them;
could you please tell me where shall i add those codes and what things shall i take care (e.g. D030 has 4 bytes with 2、3 or 4 siangls)? thanks!