Print Page - Frame reception problem in Fiat CAN ID 11 bits, 50 kbaud with STN1100 chip

Title: Frame reception problem in Fiat CAN ID 11 bits, 50 kbaud with STN1100 chip
Post by: INMOCARS on May 22, 2022, 01:21:29 PM

Hello everyone...
I am having problems receiving response frames with an Obdlink SX interface (STN1100 chip)
It's my own code in Delphi and I'm using a serial component (Lazserial from Lazarus IDE) to send and receive frames with AT commands. Same as how ELM327 is used.

If I do monitoring with arduino and canbus shield, the frames of both query and response are seen perfectly.

I have the Obdlink configured with the "ATSPC" protocol, which is the one that corresponds to the protocol that I am using USER2 CAN ID 11 bits, 50 kbaud.

I send:

Code:

  lazserial1.WriteData('85 02 10 81 00 00 00 00' + #13#10);
  SLEEP(varSLEEP1);
  listbox1.items.add(lazserial1.ReadData);
  listbox1.Refresh;
  lazserial1.WriteData('85 02 1A 95 00 00 00 00' + #13#10);
  SLEEP(varSLEEP1);
  listbox1.items.add(lazserial1.ReadData);
  listbox1.Refresh;
  lazserial1.WriteData('85 02 1A 94 00 00 00 00' + #13#10);
  SLEEP(varSLEEP1);
  listbox1.items.add(lazserial1.ReadData);
  listbox1.Refresh;
  lazserial1.WriteData('85 30 FF 00 00 00 00 00 ' + #13#10);
  SLEEP(varSLEEP1);
  listbox1.items.add(lazserial1.ReadData);
  listbox1.Refresh;

and I don't get any response via lazserial1.ReadData
in frontend console i only get "NO DATA>"
I already tried with different response times and several more configurations...

while at all times in the monitoring with arduino I get the complete frames:

1 - 7B0 85 02 10 81 00 00 00 00
2 - 7C3 F1 02 50 81 00 00 00 00
3 - 7B0 85 02 1A 95 00 00 00 00
4 - 7C3 F1 04 5A 95 01 08 00 00
5 - 7B0 85 02 1A 94 00 00 00 00
6 - 7C3 F1 10 0D 5A 94 30 34 30
7 - 7B0 85 30FF 00 00 00 00 00
8 - 7C3 F1 20 30 30 30 31 32 35
9 - 7C3 F1 21 31 31 00 00 00 00

It is as if the STN1100 or the serial component had some configuration that I am missing in order to receive the frames through the Lazserial serial component.

If there is someone who understands the subject and can give me a hand, I would appreciate it.

Thank you

Title: Re: Frame reception problem in Fiat CAN ID 11 bits, 50 kbaud with STN1100 chip
Post by: H2Deetoo on May 25, 2022, 01:12:43 AM

You need to set a filter so your cable will accept the desired CANID. check the protocol documentatuon of ELM327.

Rgs H2Deetoo

Title: Re: Frame reception problem in Fiat CAN ID 11 bits, 50 kbaud with STN1100 chip
Post by: H2Deetoo on May 28, 2022, 05:03:54 PM

By coincidence I ordered 2 cheap ELM Bluetooth adapters, and start to write some supporting code for it.

I might be able to help you further if you still need some more help.

(My main work is on VAG but I have a Fiat 500 2009 to play with as well.)

Regards,
Bonny

Title: Re: Frame reception problem in Fiat CAN ID 11 bits, 50 kbaud with STN1100 chip
Post by: prj on May 29, 2022, 03:35:16 AM

Are you sure it's 50k and not 500k?

The PTCan runs at 500k on these, but maybe you're trying to access something else.

Title: Re: Frame reception problem in Fiat CAN ID 11 bits, 50 kbaud with STN1100 chip
Post by: H2Deetoo on May 29, 2022, 03:53:27 PM

The FIAT CAN-B does run on 50kbps but it uses pin 1+9 of the OBD connector.

Btw post the initialization code of your ELM compatible device.

Title: Re: Frame reception problem in Fiat CAN ID 11 bits, 50 kbaud with STN1100 chip
Post by: H2Deetoo on May 29, 2022, 03:57:10 PM

Also some of those 50kbps CAN busses are using the "fault tolerant" drivers, which are officially not compatible with the normal can drivers.
However if you remove the 120 ohm resistor you can communicate just fine.

Rgs H2Deetoo

Title: Re: Frame reception problem in Fiat CAN ID 11 bits, 50 kbaud with STN1100 chip
Post by: woj on June 05, 2022, 01:13:14 PM

The only ever actual problem I had with my Fiat and (Chinese) ELM327 was the said resistor, with it on the interface some things were just not working (not with my own software, not with MES). And if my memory serves me right, it was in the slow CAN mode, the fast one worked fine, but that was ages ago, so I perhaps remember it the other way round.

Otherwise, using a terminal program of some sort (PuTTY or something like this) is really much more comfortable in debugging this kind of thing. If it helps you, attached is the initialisation protocol MES used to use for fast CAN with 29bit IDs that I sniffed on some long time ago to enable my own ELM327 games.

(The question mark on the 10 03 request is a leftover from these old times, at the time I did not know what it was for).

NefMoto

Technical => Communication Protocols => Topic started by: INMOCARS on May 22, 2022, 01:21:29 PM