Thread: code wizards, help with some coding? (OBDII diagnostic codes)

OK, yeah the $0E threw me off.

How about:
P0100
P0200
P0300
C0300
B0200
U0100

Originally Posted by CTdubbin

if it's really that easy, i don't know why someone hasn't just whipped it up real quick. my only guess is those same people who could whip it up real quick already have their hand in the cookie jar (so to speak). and i'm not going to knock their hustle....

For what it's worth, here is some of my code.
It assumes the response from the ELM to a $03 request is contained in the buffer 'ELMrxstr' in the fomat '43 01 33 00 00 00 00' and the number of codes is in 'num_codes'.
At this point it only handles up to 3 stored DTC's and it does not handle the CAN format (yet).

I don't know about others, but I am always a little reluctant to post my code because I am just a hacker, so don't be too hard on me !

(I'm not sure how to use the code window, I hope it is readable. And I don't think the quote at the start from CTdubbin worked quite right?? )

Code:

	if(num_codes > 0)
	{		
		sendMODEcmd(0x03);				/* request the trouble codes, wait for response */
			
			/* --------------- first trouble code ------------------ */
		MAX_goto_row_col(4,2);				/* set cursor */
		show_code_hdr(ELMrxstr[3]);			/* 1st char of 1st code */
		printf("%c", ELMrxstr[4]);			/* print next char */
		printf("%c", ELMrxstr[6]);			/* ... and next char */
		printf("%c", ELMrxstr[7]);			/* ... and last char */

			/* --------------- second trouble code ------------------ */
		if(ELMrxstr[10] == 0x30 & ELMrxstr[12] == 0x30 & ELMrxstr[13] == 0x30);		/* 000 = no code */
		else
		{
			MAX_goto_row_col(5,2);				/* set cursor */
			show_code_hdr(ELMrxstr[9]);			/* 1st char of 2nd code */
			printf("%c", ELMrxstr[10]);			/* print next char */
			printf("%c", ELMrxstr[12]);			/* ... and next char */
			printf("%c", ELMrxstr[13]);			/* ... and last char */
		}

			/* --------------- third trouble code ------------------ */
		if(ELMrxstr[16] == 0x30 & ELMrxstr[18] == 0x30 & ELMrxstr[19] == 0x30);		/* 000 = no code */
		else
		{
			MAX_goto_row_col(6,2);				/* set cursor */
			show_code_hdr(ELMrxstr[15]);		/* 1st char of 2nd code */
			printf("%c", ELMrxstr[16]);			/* print next char */
			printf("%c", ELMrxstr[18]);			/* ... and next char */
			printf("%c", ELMrxstr[19]);			/* ... and last char */
		}
	}

/* ----------------------------------------------------- */
// show_code_hdr()
//
// Show the first part of a trouble code.
// Pass the first byte of a trouble code to this function.
// Set cursor position before calling this function.
//
/* ----------------------------------------------------- */
void show_code_hdr(unsigned char value)
{
	switch(value)
	{
		case 0x30:				/* '0' Powertrain Code - SAE defined */
		{
			printf("P0");
			break ;	
		}
		case 0x31:				/* '1' Powertrain Code - manufacturer defined */
		{
			printf("P1");
			break ;	
		}
		case 0x32:				/* '2' Powertrain Code - SAE defined */
		{
			printf("P2");
			break ;	
		}
		case 0x33:				/* '3' Powertrain Code - jointly defined */
		{
			printf("P3");
			break ;	
		}
		case 0x34:				/* '4' Chassis Code - SAE defined  */
		{
			printf("C0");
			break ;	
		}
		case 0x35:				/* '5' Chassis Code - manufacturer defined */
		{
			printf("C1");
			break ;	
		}
		case 0x36:				/* '6' Chassis Code - manufacturer defined */
		{
			printf("C2");
			break ;	
		}
		case 0x37:				/* '7' Chassis Code - reserved for future */
		{
			printf("C3");
			break ;	
		}
		case 0x38:				/* '8' Body Code - SAE defined */
		{
			printf("B0");
			break ;	
		}
		case 0x39:				/* '9' Body Code - manufacturer defined */
		{
			printf("B1");
			break ;	
		}
		case 0x41:				/* 'A' Body Code - manufacturer defined */
		{
			printf("B2");
			break ;	
		}
		case 0x42:				/* 'B' Body Code - reserved for future */
		{
			printf("B3");
			break ;	
		}
		case 0x43:				/* 'C' Network Code - SAE defined */
		{
			printf("U0");
			break ;	
		}
		case 0x44:				/* 'D' Network Code - manufacturer defined */
		{
			printf("U1");
			break ;	
		}
		case 0x45:				/* 'E' Network Code - manufacturer defined */
		{
			printf("U2");
			break ;	
		}
		case 0x46:				/* 'F' Network Code - reserved for future */
		{
			printf("U3");
			break ;	
		}
		default:				/* unrecognized */
		{
			printf("xx");
			break ;	
		}
	}
}

Do I win a free ELMScan?

@Rooster, can I be just a little hard on you?
Try something more like post #5. You should also convert the hex text into data first, using atoh() or something similar. It will be a lot easier on you in the long run.
The problem with a switch/case like that is bits A5 and A4 are now reserved for a 5th digit with 2008+ models.
So in C/C++...
char cECU[4] = {'P', 'C', 'B', 'U'};

printf("DTC %c%X%02X", cECU[bytes[0] >> 6], bytes[0] & 0x3F, bytes[1] );

Note the 0x3F. The first byte can be anywhere from P0 to U39 in BCD.

Thanks for the tips.

Originally Posted by Vitaliy

Almost! You did very well but sorry -- it was a trick question!

18 DA F1 10 10 0E 43 06 01 00 02 00
18 DA F1 10 21 03 00 43 00 82 00 C1
18 DA F1 10 22 00 00 00 00 00 00 00

So the parts in blue are the headers, followed by the sequence numbers. So far so good. What tripped you up was the fact that you also have a byte count ($0E = 15), followed by reply to mode 3 ($43), followed by the number of DTCs (06).

Wanna give it another try?

Vitaliy

I could translate that...or I could just pull up the data sheet on one of your simulators.