OBD2 serial command over wi-fi

Question

I'm looking for sending serial commands to an OBD-II wi-fi device via my iPad.

In order to do it, I've use CocoaAsyncSocket lib to connect my iPad to the OBD-II and it works fine. Then, I've send a command "010C/r" to the device to get the rpm of the car, but it doesn't work. I think I don't use the right syntax to do it, but I'm not sure.

Here is my Objective-C code:

static const int ddLogLevel = LOG_LEVEL_VERBOSE;

#define HOST @"192.168.0.10"

#define USE_SECURE_CONNECTION    0
#define VALIDATE_SSL_CERTIFICATE 1

#define READ_HEADER_LINE_BY_LINE 0


@implementation SimpleHTTPClientAppDelegate

@synthesize window = _window;
@synthesize viewController = _viewController;

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{

    [DDLog addLogger:[DDTTYLogger sharedInstance]];

    DDDispatchQueueLogFormatter *formatter = [[DDDispatchQueueLogFormatter alloc] init];
    [formatter setReplacementString:@"socket" forQueueLabel:GCDAsyncSocketQueueName];
    [formatter setReplacementString:@"socket-cf" forQueueLabel:GCDAsyncSocketThreadName];

    [[DDTTYLogger sharedInstance] setLogFormatter:formatter];

    asyncSocket = [[GCDAsyncSocket alloc] initWithDelegate:self delegateQueue:dispatch_get_main_queue()];

    NSError *error = nil;
    NSString *host = HOST;

#if USE_SECURE_CONNECTION
    uint16_t port = 443; // HTTPS
#else
    uint16_t port = 35000;  // HTTP
#endif

    if (![asyncSocket connectToHost:host onPort:port error:&error])
    {
        DDLogError(@"Unable to connect to due to invalid configuration: %@", error);
    }
    else
    {
        DDLogVerbose(@"Connecting to \"%@\" on port %hu...", host, port);
    }

#if USE_SECURE_CONNECTION

    #if VALIDATE_SSL_CERTIFICATE
    {
        DDLogVerbose(@"Requesting StartTLS with options: (nil)");
        [asyncSocket startTLS:nil];
    }
    #else
    {
        NSDictionary *options =
            [NSDictionary dictionaryWithObject:[NSNumber numberWithBool:NO]
                                        forKey:(NSString *)kCFStreamSSLValidatesCertificateChain];

        DDLogVerbose(@"Requesting StartTLS with options:\n%@", options);
        [asyncSocket startTLS:options];
    }
    #endif

#endif

    self.window.rootViewController = self.viewController;
    [self.window makeKeyAndVisible];
    return YES;
}

- (void)socket:(GCDAsyncSocket *)sock didConnectToHost:(NSString *)host port:(UInt16)port
{
    DDLogVerbose(@"socket:didConnectToHost:%@ port:%hu", host, port);

    NSString *requestStrFrmt = @"010C\r";

    NSString *requestStr = [NSString stringWithFormat:requestStrFrmt, HOST];
    NSData *requestData = [requestStr dataUsingEncoding:NSUTF8StringEncoding];

    [asyncSocket writeData:requestData withTimeout:-1.0 tag:0];

    DDLogVerbose(@"Sending HTTP Request:\n%@", requestStr);

#if READ_HEADER_LINE_BY_LINE

    [asyncSocket readDataToData:[GCDAsyncSocket CRLFData] withTimeout:-1.0 tag:0];

#else

    NSData *responseTerminatorData = [@"\r\n\r\n" dataUsingEncoding:NSASCIIStringEncoding];

    [asyncSocket readDataToData:responseTerminatorData withTimeout:-1.0 tag:0];

#endif
}

- (void)socketDidSecure:(GCDAsyncSocket *)sock
{
    DDLogVerbose(@"socketDidSecure:");
}

- (void)socket:(GCDAsyncSocket *)sock didWriteDataWithTag:(long)tag
{
    DDLogVerbose(@"socket:didWriteDataWithTag:");
}

- (void)socket:(GCDAsyncSocket *)sock didReadData:(NSData *)data withTag:(long)tag
{
    DDLogVerbose(@"socket:didReadData:withTag:");

    NSString *httpResponse = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];

#if READ_HEADER_LINE_BY_LINE

    DDLogInfo(@"Line httpResponse: %@", httpResponse);

    if ([data length] == 2)
    {
        DDLogInfo(@"<done>");
    }
    else
    {
        [asyncSocket readDataToData:[GCDAsyncSocket CRLFData] withTimeout:-1.0 tag:0];
    }

#else

    DDLogInfo(@"Full HTTP Response:\n%@", httpResponse);

#endif

}

- (void)socketDidDisconnect:(GCDAsyncSocket *)sock withError:(NSError *)err
{
    DDLogVerbose(@"socketDidDisconnect:withError: \"%@\"", err);
}


@end

Here is the logs:

2014-05-28 17:02:05:559 [main] Connecting to "192.168.0.10" on port 35000...
2014-05-28 17:02:05:619 [main] socket:didConnectToHost:192.168.0.10 port:35000
2014-05-28 17:02:05:621 [main] Sending HTTP Request:
010C

2014-05-28 17:02:05:622 [main] socket:didWriteDataWithTag:

Thx

Eric Smekens · Answer 1 · 2014-05-29T16:52:32.557

0

Try '010C\r' instead of '010C/r'. You are using the carriage return correctly, but the slash should be the other way!

OBD-II protocol uses the CR as a ending commando, if you don't send it, it will keep listening, but it should give a timeout when you wait for a long time, I believe. Need to check on that.

edited May 29 '14 at 16:52

answered May 29 '14 at 16:46

Eric Smekens

1,602
20
32

What do you get as response? Does it work when you use a terminal instead? – Eric Smekens May 30 '14 at 10:18
When i use iOS i get this : `2014-05-28 17:02:05:621 [main] Sending HTTP Request: 010C 2014-05-28 17:02:05:622 [main] socket:didWriteDataWithTag:` I've tried with terminal and python and it works. – user3684398 May 30 '14 at 10:40

score 0 · Answer 2 · answered Aug 18 '16 at 19:37

0

As per V.250, AT commands are terminated with \r\n.

answered Aug 18 '16 at 19:37

DrMickeyLauer

4,455
3
31
67

OBD2 serial command over wi-fi

2 Answers2