List of SerialPorts queried using WMI differs from devicemanager? - wmi

Question

I have the following serial ports listed in my devicemanager:
COM3
COM4 (BT)
COM5 (BT)
COM6 (GlobeTrotter MO67xx - Control Interface)
COM7 (GlobeTrotter MO67xx - GPS Control Interface)
COM8 (GlobeTrotter MO67xx - GPS Data Interface)
COM9 (GlobeTrotter MO67xx - Diagnostics Interface)
COM11 (USB Serial Port)
COM12 (USB Serial Port)
COM45 (SUNIX COM Port)
COM46 (SUNIX COM Port)
The SUNIX COM ports are connected via an internal PCI-Card.
The USB Serial Port is connected via USB (FDTI-chip)
The GlobeTrotter ports are from a GlobeTrotter device connected via USB. There are also a modem, a USB-device and a network device listed for this modem.
So I have several different sources of serial ports.
All I want to do is to get a list containing all those ports using WMI.
For my tests I am using WMI Code Creator
Test 1:
root\CIMV2; Query: SELECT * FROM Win32_SerialPort only returns the following serial ports:
COM3
COM4
COM5
Test 2:
root\WMI; Query: SELECT * FROM MSSerial_PortName only returns the following serial ports:
COM3
COM11
COM12
COM45
COM45
How can I get a complete list of serial ports?

Answer 1

I found the solution.
The following query (root\CIMV2) gets the requested results:
SELECT * FROM Win32_PnPEntity WHERE ClassGuid="{4d36e978-e325-11ce-bfc1-08002be10318}"
Update
This answer is pretty old now. Ehen I asked it I still had to consider WinXP and was using Windows7.
Since I don't deal with serial ports any more, I can't give any new information on that issue. At that time this solution reported all ports that the devicemanager was showing. But I know listing serial ports is not that easy so this answer might not be correct in all scenarios.

Answer 2

In my case, I have physical serial ports, USB serial ports, and com0com virtual serial ports. I need both the full names and COM port addresses.
The query suggested in this answer does not find com0com ports. The query suggested in this answer requires Administrator priviledges.
SELECT * FROM Win32_PnPEntity find all devices. It returns physical devices like this, and address can be parsed from Caption:
Serial Port for Barcode Scanner (COM13)
However, for com0com ports Caption is like this (no address):
com0com - serial port emulator
SELECT * FROM Win32_SerialPort returns addresses (DeviceID), as well as full names (Name). However, it only finds physical serial ports and com0com ports, not USB serial ports.
So in the end, I need two WMI calls: SELECT * FROM Win32_SerialPort (address is DeviceID) and SELECT * FROM Win32_PnPEntity WHERE Name LIKE '%(COM%' (address can be parsed from Caption). I have narrowed down the Win32_PnPEntity call, because it only needs to find devices that were not found in the first call.
This C++ code can be used to find all serial ports:
// Return list of serial ports as (number, name)
std::map<int, std::wstring> enumerateSerialPorts()
{
std::map<int, std::wstring> result;
HRESULT hres;
hres = CoInitializeEx(0, COINIT_APARTMENTTHREADED);
if (SUCCEEDED(hres) || hres == RPC_E_CHANGED_MODE) {
hres = CoInitializeSecurity(
NULL,
-1, // COM authentication
NULL, // Authentication services
NULL, // Reserved
RPC_C_AUTHN_LEVEL_DEFAULT, // Default authentication
RPC_C_IMP_LEVEL_IMPERSONATE, // Default Impersonation
NULL, // Authentication info
EOAC_NONE, // Additional capabilities
NULL // Reserved
);
if (SUCCEEDED(hres) || hres == RPC_E_TOO_LATE) {
IWbemLocator *pLoc = NULL;
hres = CoCreateInstance(
CLSID_WbemLocator,
0,
CLSCTX_INPROC_SERVER,
IID_IWbemLocator, (LPVOID *) &pLoc);
if (SUCCEEDED(hres)) {
IWbemServices *pSvc = NULL;
// Connect to the root\cimv2 namespace with
// the current user and obtain pointer pSvc
// to make IWbemServices calls.
hres = pLoc->ConnectServer(
bstr_t(L"ROOT\\CIMV2"), // Object path of WMI namespace
NULL, // User name. NULL = current user
NULL, // User password. NULL = current
0, // Locale. NULL indicates current
NULL, // Security flags.
0, // Authority (for example, Kerberos)
0, // Context object
&pSvc // pointer to IWbemServices proxy
);
if (SUCCEEDED(hres)) {
hres = CoSetProxyBlanket(
pSvc, // Indicates the proxy to set
RPC_C_AUTHN_WINNT, // RPC_C_AUTHN_xxx
RPC_C_AUTHZ_NONE, // RPC_C_AUTHZ_xxx
NULL, // Server principal name
RPC_C_AUTHN_LEVEL_CALL, // RPC_C_AUTHN_LEVEL_xxx
RPC_C_IMP_LEVEL_IMPERSONATE, // RPC_C_IMP_LEVEL_xxx
NULL, // client identity
EOAC_NONE // proxy capabilities
);
if (SUCCEEDED(hres)) {
// Use Win32_PnPEntity to find actual serial ports and USB-SerialPort devices
// This is done first, because it also finds some com0com devices, but names are worse
IEnumWbemClassObject* pEnumerator = NULL;
hres = pSvc->ExecQuery(
bstr_t(L"WQL"),
bstr_t(L"SELECT Name FROM Win32_PnPEntity WHERE Name LIKE '%(COM%'"),
WBEM_FLAG_FORWARD_ONLY | WBEM_FLAG_RETURN_IMMEDIATELY,
NULL,
&pEnumerator);
if (SUCCEEDED(hres)) {
constexpr size_t max_ports = 30;
IWbemClassObject *pclsObj[max_ports] = {};
ULONG uReturn = 0;
do {
hres = pEnumerator->Next(WBEM_INFINITE, max_ports, pclsObj, &uReturn);
if (SUCCEEDED(hres)) {
for (ULONG jj = 0; jj < uReturn; jj++) {
VARIANT vtProp;
pclsObj[jj]->Get(L"Name", 0, &vtProp, 0, 0);
// Name should be for example "Serial Port for Barcode Scanner (COM13)"
const std::wstring deviceName = vtProp.bstrVal;
const std::wstring prefix = L"(COM";
size_t ind = deviceName.find(prefix);
if (ind != std::wstring::npos) {
std::wstring nbr;
for (size_t i = ind + prefix.length();
i < deviceName.length() && isdigit(deviceName[i]); i++)
{
nbr += deviceName[i];
}
try {
const int portNumber = boost::lexical_cast<int>(nbr);
result[portNumber] = deviceName;
}
catch (...) {}
}
VariantClear(&vtProp);
pclsObj[jj]->Release();
}
}
} while (hres == WBEM_S_NO_ERROR);
pEnumerator->Release();
}
// Use Win32_SerialPort to find physical ports and com0com virtual ports
// This is more reliable, because address doesn't have to be parsed from the name
pEnumerator = NULL;
hres = pSvc->ExecQuery(
bstr_t(L"WQL"),
bstr_t(L"SELECT DeviceID, Name FROM Win32_SerialPort"),
WBEM_FLAG_FORWARD_ONLY | WBEM_FLAG_RETURN_IMMEDIATELY,
NULL,
&pEnumerator);
if (SUCCEEDED(hres)) {
constexpr size_t max_ports = 30;
IWbemClassObject *pclsObj[max_ports] = {};
ULONG uReturn = 0;
do {
hres = pEnumerator->Next(WBEM_INFINITE, max_ports, pclsObj, &uReturn);
if (SUCCEEDED(hres)) {
for (ULONG jj = 0; jj < uReturn; jj++) {
VARIANT vtProp1, vtProp2;
pclsObj[jj]->Get(L"DeviceID", 0, &vtProp1, 0, 0);
pclsObj[jj]->Get(L"Name", 0, &vtProp2, 0, 0);
const std::wstring deviceID = vtProp1.bstrVal;
if (deviceID.substr(0, 3) == L"COM") {
const int portNumber = boost::lexical_cast<int>(deviceID.substr(3));
const std::wstring deviceName = vtProp2.bstrVal;
result[portNumber] = deviceName;
}
VariantClear(&vtProp1);
VariantClear(&vtProp2);
pclsObj[jj]->Release();
}
}
} while (hres == WBEM_S_NO_ERROR);
pEnumerator->Release();
}
}
pSvc->Release();
}
pLoc->Release();
}
}
CoUninitialize();
}
if (FAILED(hres)) {
std::stringstream ss;
ss << "Enumerating serial ports failed. Error code: " << int(hres);
throw std::runtime_error(ss.str());
}
return result;
}

Answer 3

The Win32_SerialPort class used in this article reports the physical com ports, if you wanna enumerate all the serial ports including the USB-Serial/COM ports, you must use the MSSerial_PortName class located in the root\wmi namespace.
Also try these classes located in the same namespace
MSSerial_CommInfo
MSSerial_CommProperties
MSSerial_HardwareConfiguration
MSSerial_PerformanceInformation
Note : If you want to know the properties and methods of this class you can use the WMI Delphi Code Creator.

Answer 4

I had a similar issues trying to have an application locate the COM port for a USB Serial device.
By using the scope \\localhost\root\CIMV2 for the query SELECT * FROM Win32_PnPEntity WHERE ConfigManagerErrorCode = 0, the application was able to find COM ports via each returned object's caption or locate the exact port by checking the caption for the device name.
ManagementObjectSearcher comPortSearcher = new ManagementObjectSearcher(#"\\localhost\root\CIMV2", "SELECT * FROM Win32_PnPEntity WHERE ConfigManagerErrorCode = 0");
using (comPortSearcher)
{
string caption = null;
foreach (ManagementObject obj in comPortSearcher.Get())
{
if (obj != null)
{
object captionObj = obj["Caption"];
if (captionObj != null)
{
caption = captionObj.ToString();
if (caption.Contains("CH340"))
{
_currentSerialSettings.PortName = caption.Substring(caption.LastIndexOf("(COM")).Replace("(", string.Empty).Replace(")", string.Empty);
}
}
}
}
}
The parsing code was found at [C#] How to programmatically find a COM port by friendly name