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

PassThruLogicalDisconnect v5.0

Closing a logical communication channel

Last updated: January 13, 2026

Description

The function terminates the logical connection to the vehicle on the specified pass-thru device.

On success, the function returns STATUS_NOERROR, and the logical communication channel transitions to the disconnected state.

long PassThruLogicalDisconnect(unsigned long ChannelID)

Disconnected channel state

After disconnection, the logical channel has the following state:

• The channel identifier becomes invalid
• All periodic messages are removed and their identifiers become invalid
• All configurable parameters are reset to their default values
• All messages in the transmit queue are discarded (without generating TxFailed)
• All messages in the receive queue are discarded
• Any active message transmission is aborted (without generating TxFailed)

Parameters

ChannelID

Input parameter. The identifier of the logical communication channel obtained from the call to PassThruLogicalConnect().

Return error codes

Code	Description
STATUS_NOERROR	Function completed successfully
ERR_CONCURRENT_API_CALL	A J2534 API function was called before the previous call completed
ERR_DEVICE_NOT_OPEN	PassThruOpen() has not been successfully called
ERR_INVALID_CHANNEL_ID	Invalid ChannelID value
ERR_DEVICE_NOT_CONNECTED	Communication error with the pass-thru device. The device has been disconnected.
ERR_NOT_SUPPORTED	The DLL does not support this function
ERR_FAILED	Undefined error. Use PassThruGetLastError() to get a description.

Examples

C/C++ example

#include "j2534_dll.hpp"

unsigned long logicalChannelID = ...; // ID obtained from PassThruLogicalConnect

// Close the logical channel
long ret = PassThruLogicalDisconnect(logicalChannelID);

if (ret == STATUS_NOERROR) {
    printf("Logical channel closed\n");
} else {
    char error[256];
    PassThruGetLastError(error);
    printf("Error: %s\n", error);
}

Python example (ctypes)

from ctypes import *

j2534 = cdll.LoadLibrary("libj2534_v05_00.dylib")

logical_channel_id = c_ulong(...)  # ID obtained from PassThruLogicalConnect

# Close the logical channel
ret = j2534.PassThruLogicalDisconnect(logical_channel_id)

if ret == 0:  # STATUS_NOERROR
    print("Logical channel closed")
else:
    error = create_string_buffer(256)
    j2534.PassThruGetLastError(error)
    print(f"Error: {error.value.decode()}")

Related functions

• PassThruLogicalConnect() - Create a logical channel
• PassThruDisconnect() - Close a physical connection
• PassThruClose() - Close the device

1. up