1. Home Page
2. ScanDoc Development
3. J2534 Manual
4. PassThru functions reference

PassThruScanForDevices v5.0

Scan for devices

Last modified: January 13, 2026

Description

The function scans for available ScanDoc adapters and returns the number of devices found. This function is part of the SAE J2534-1 standard and is intended for device discovery before calling PassThruOpen().

long PassThruScanForDevices(unsigned long* pDeviceCount)

Parameters

• pDeviceCount - Pointer to an unsigned long variable allocated by the application. On successful return, the variable will contain the number of devices found.

How it works

The function performs the following steps:

1. Scans for available ScanDoc devices on the local network (LAN/WiFi)
2. If Bluetooth is enabled, scans for BLE devices
3. Writes the number of devices found to pDeviceCount
4. Stores the device list for later retrieval via PassThruGetNextDevice()

Function call order

PassThruScanForDevices()  → Scan for available devices
    ↓
PassThruGetNextDevice()   → Retrieve information about each device (call N times)
    ↓
PassThruOpen()            → Open a connection to the selected device
    ↓
...

Timeouts

Network scan timeout: 2000 ms. BLE scan timeout: 3000 ms. Total execution time can be up to 5 seconds when Bluetooth is enabled.

Returned error codes

Code	Description	Possible causes and solutions
STATUS_NOERROR	Function completed successfully	The number of devices found has been written to pDeviceCount (may be 0)
ERR_NULL_PARAMETER	pDeviceCount pointer not provided	Pass a valid pointer to an unsigned long variable
ERR_CONCURRENT_API_CALL	A J2534 API function is already running	Another J2534 function has not yet completed Solution: wait for the previous call to complete
ERR_NOT_SUPPORTED	Function not supported	The DLL does not support dynamic device scanning Solution: call PassThruOpen() directly with known parameters
ERR_FAILED	Internal error	Network interface error Bluetooth initialization error Solution: use PassThruGetLastError() to obtain details

Examples

C/C++ example

#include "j2534_dll.hpp"

unsigned long deviceCount = 0;

// Scan for devices
long ret = PassThruScanForDevices(&deviceCount);
if (ret != STATUS_NOERROR)
{
    char error[256];
    PassThruGetLastError(error);
    printf("Scan error: %s\n", error);
    return;
}

printf("Devices found: %lu\n", deviceCount);

if (deviceCount == 0)
{
    printf("No devices found\n");
    return;
}

// Retrieve information about each device
SDEVICE deviceInfo;
for (unsigned long i = 0; i < deviceCount; i++)
{
    ret = PassThruGetNextDevice(&deviceInfo);
    if (ret == STATUS_NOERROR)
    {
        printf("Device %lu: %s\n", i + 1, deviceInfo.DeviceName);
    }
}

Kotlin example (Android)

val j2534 = J2534JNI(context)

// Scan for devices
val scanResult = j2534.ptScanForDevices()

if (scanResult.status == STATUS_NOERROR) {
    Log.i("J2534", "Devices found: ${scanResult.deviceCount}")

    // Retrieve information about each device
    for (i in 0 until scanResult.deviceCount) {
        val deviceInfo = j2534.ptGetNextDevice()
        if (deviceInfo.status == STATUS_NOERROR) {
            Log.i("J2534", "Device ${i + 1}: ${deviceInfo.deviceName}")
        }
    }
} else {
    Log.e("J2534", "Scan error: ${scanResult.status}")
}

Python example (ctypes)

from ctypes import *
import platform

# Load the library
if platform.system() == "Windows":
    j2534 = windll.LoadLibrary("j2534sd_v05_00_x64.dll")
elif platform.system() == "Darwin":
    j2534 = cdll.LoadLibrary("libj2534_v05_00.dylib")
else:
    j2534 = cdll.LoadLibrary("libj2534_v05_00.so")

device_count = c_ulong()

# Scan for devices
ret = j2534.PassThruScanForDevices(byref(device_count))

if ret == 0:  # STATUS_NOERROR
    print(f"Devices found: {device_count.value}")

    # SDEVICE structure for retrieving device information
    class SDEVICE(Structure):
        _fields_ = [
            ("DeviceName", c_char * 80),
            ("DeviceAvailable", c_ulong),
            ("DeviceDLLFWStatus", c_ulong),
            ("DeviceConnectMedia", c_ulong),
            ("DeviceConnectSpeed", c_ulong),
            ("DeviceSignalQuality", c_ulong),
            ("DeviceSignalStrength", c_ulong)
        ]

    # Retrieve information about each device
    for i in range(device_count.value):
        device_info = SDEVICE()
        ret = j2534.PassThruGetNextDevice(byref(device_info))
        if ret == 0:
            print(f"Device {i + 1}: {device_info.DeviceName.decode()}")
else:
    error = create_string_buffer(256)
    j2534.PassThruGetLastError(error)
    print(f"Error: {error.value.decode()}")

C# example (P/Invoke)

using System;
using System.Runtime.InteropServices;

[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)]
public struct SDEVICE
{
    [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 80)]
    public string DeviceName;
    public uint DeviceAvailable;
    public uint DeviceDLLFWStatus;
    public uint DeviceConnectMedia;
    public uint DeviceConnectSpeed;
    public uint DeviceSignalQuality;
    public uint DeviceSignalStrength;
}

class J2534
{
    [DllImport("j2534sd_v05_00_x64.dll", CallingConvention = CallingConvention.StdCall)]
    public static extern int PassThruScanForDevices(out uint pDeviceCount);

    [DllImport("j2534sd_v05_00_x64.dll", CallingConvention = CallingConvention.StdCall)]
    public static extern int PassThruGetNextDevice(out SDEVICE psDevice);

    [DllImport("j2534sd_v05_00_x64.dll", CallingConvention = CallingConvention.StdCall)]
    public static extern int PassThruGetLastError(
        [MarshalAs(UnmanagedType.LPStr)] System.Text.StringBuilder pErrorDescription);
}

// Usage:
uint deviceCount;
int ret = J2534.PassThruScanForDevices(out deviceCount);

if (ret == 0) // STATUS_NOERROR
{
    Console.WriteLine($"Devices found: {deviceCount}");

    for (uint i = 0; i < deviceCount; i++)
    {
        SDEVICE deviceInfo;
        ret = J2534.PassThruGetNextDevice(out deviceInfo);
        if (ret == 0)
        {
            Console.WriteLine($"Device {i + 1}: {deviceInfo.DeviceName}");
        }
    }
}
else
{
    var error = new System.Text.StringBuilder(256);
    J2534.PassThruGetLastError(error);
    Console.WriteLine($"Error: {error}");
}

Related functions

• PassThruGetNextDevice() - Retrieve information about discovered devices
• PassThruOpen() - Establish communication with the adapter

1. up