RS232/RS485

TVFestus · Jul 9th 2009

Soweit ich das verstanden habe lässt sich beispielsweise für COM2 über den Registryeintrag RTS_CONTROL_TOGGLE die Funktionalität der Schnittstelle zwischen RS232 und RS485 umschalten.

Meine Frage hierzu ist:
Lässt sich das auch während des Betriebs umschalten oder muss die PicoMod neu gebootet werden? Hintergrund ist, dass wir gerne sowohl RS232 als auch RS485 über die gleiche Busche bereitstellen möchten und der Benutzer die Funktionalität einfach umschalten kann.

fs-support_MK · Jul 10th 2009

You don't need to reboot the PicoCOM to get the configuration changes working. You can use DeactiveDevice ActiveDevice to re-initiate the serial driver.
Please refere to the MSDN page for more details: ActivateDevice reference

Festus · Jul 13th 2009

Can you please give me an example of using ActivateDevice and DeactivateDevice in C#?

Function declaration (in class DeviceHandle):

Code

[DllImport("coredll.dll", EntryPoint = "ActivateDevice", SetLastError = true)]
public static extern IntPtr ActivateDevice(
string lpszDevKey,
Int16 dwClientInfo);

When I call the function with:

Code

IntPtr handle = DeviceHandle.ActivateDevice(@"Drivers\BuiltIn\Serial3", 0);
int error = DeviceHandle.GetLastError();

handle is Zero and error code is 87.

fs-support_MK · Jul 13th 2009

Error code 87 means "invalid parameter" (-> Windows CE error codes)

Please try to open it with:

Code

IntPtr handle = DeviceHandle.ActivateDevice(L"Drivers\\BuiltIn\\Serial3", 0);

Festus · Jul 13th 2009

Hello Mr. Kiepfer,

for what does the L" stands for? I can't use this in C#

WhenI try to run this function while the driver is already active, I get error code 2404 (ERROR_DEVICE_IN_USE)

fs-support_MK · Jul 14th 2009

The L" is used in C++ to instruct the compiler that the following string should be a wide-charachter string. In C# all strings are wide-characters automatically I suppose. So you don't need the L.

Quote from "Festus"

When try to run this function while the driver is already active, I get error code 2404 (ERROR_DEVICE_IN_USE)

It looks like another application is still using COM3. Are you sure that this isn't the case. Maybe you have configured NDCUCFG to run on COM3.

Festus · Jul 14th 2009

I only get Error 2404 when I try to activate the driver and the driver is already active (listed under Drivers\Active registry key). I'm able to deactivate the driver with DeactivateDevice(Handle) and after calling this function, the driver is removed from Drivers\Active.

When I try to activate the driver after I have deacivated it using the Function DeactivateDevice(HANDLE) then I get the error 87.

I also have tested the syntax by deacivating and activating the digital IO driver by simplay replacing "Serial2" with "DIGITALIO" and that workes without any problem ( the only thing is that after reactivating the driver there is a missing registry entry in Drivers\Active\XX\ named BusParent?!

fs-support_MK · Jul 14th 2009

Quote from "Festus"

I only get Error 2404 when I try to activate the driver and the driver is already active (listed under Drivers\Active registry key). I'm able to deactivate the driver with DeactivateDevice(Handle) and after calling this function, the driver is removed from Drivers\Active.

This behaviour seems to be correct for me. If a device is activated already it will not be allowed to activate the device again.

Quote from "Festus"

When I try to activate the driver after I have deacivated it using the Function DeactivateDevice(HANDLE) then I get the error 87.

To activate the device you must use the ActiveDevice function. Maybe this was a mistake in writing?

To to re-initialize a driver you must first deactivate it and then activate it again. This should also be able for the serial driver.
Could you please post some more example code?

Festus · Jul 14th 2009

OK I have a form with two button, one for Activation, obe for Deactivation. De Activation/Deactivation is performed in the buttons Click event.

Code

private void btnActivate_Click(object sender, EventArgs e)
{
IntPtr handle = DeviceHandle.ActivateDevice("Drivers\\BuiltIn\\Serial2", 0);
int error = System.Runtime.InteropServices.Marshal.GetLastWin32Error();
}
private void btnDeactivate_Click(object sender, EventArgs e)
{
int error;
IntPtr hnd = DeviceHandle.FindDevice("COM2");
error = System.Runtime.InteropServices.Marshal.GetLastWin32Error();
int result = DeviceHandle.DeactivateDevice(hnd);
error = System.Runtime.InteropServices.Marshal.GetLastWin32Error();
}

Display More

The class DeviceHandle contains PInvoke functions:

Code

[DllImport("coredll.dll", EntryPoint = "ActivateDevice", SetLastError = true)]
public static extern IntPtr ActivateDevice(
string lpszDevKey,
Int32 dwClientInfo);
[DllImport("coredll.dll", EntryPoint = "DeactivateDevice", SetLastError = true)]
public static extern int DeactivateDevice(IntPtr handle);
[DllImport("coredll.dll", SetLastError = true)]
public static extern IntPtr FindFirstDevice(
DeviceSearchType searchType,
IntPtr searchParam,
ref DEVMGR_DEVICE_INFORMATION pdi);
public static IntPtr FindDevice(string searchParamString)
{
try
{
DeviceSearchType searchType = DeviceSearchType.DeviceSearchByDeviceName;
DEVMGR_DEVICE_INFORMATION pdi = new DEVMGR_DEVICE_INFORMATION();
pdi.dwSize = (uint)System.Runtime.InteropServices.Marshal.SizeOf(typeof(DEVMGR_DEVICE_INFORMATION));
IntPtr searchParam = Marshal.AllocHGlobal(searchParamString.Length);
searchParam = Marshal.StringToBSTR(searchParamString);
IntPtr device = FindFirstDevice(searchType, searchParam, ref pdi);
return pdi.hDevice;
}
catch (Exception err)
{
return IntPtr.Zero;
}
}

Display More

There is no problem with deactivation. When I click btnDeactivate, I get the correct handle with FindDevice("COM2") and I can deactivate the driver with DeactivateDevice(handle). After deactivation the registry entry of COM2 is removed from "Drivers\Active" and if I click btnDeactivation again, I get error 18 (ERROR_NO_MORE_FILES).

So I should be able to reactivate the driver again when I click btnActivate but the IntPtr is zero and I get error 87 when I click it.

I have no problems when I try the same with digitalIO driver. When I replace "Serial2" with "DIGITALIO" and "COM2" with "DIO1" the digital IO driver can be deactivated and activated without problem.

Festus · Jul 14th 2009

The same problem occurs when I try it with C++. I'm not 100% familiar with C++ but the functions seems to be correct. Deactivation works, Activation works not. When I change "Serial2" to "DIGITALIO" and "COM2" to "DIO1", it works...

Code

void CCPP_MFCDlg::OnBnClickedButton2()
{
HANDLE hnd = ::ActivateDevice(L"Drivers\\BuiltIn\\Serial2",0);
DWORD error = GetLastError();
}
void CCPP_MFCDlg::OnBnClickedButton1()
{
DEVMGR_DEVICE_INFORMATION pdi;
pdi.dwSize = sizeof(DEVMGR_DEVICE_INFORMATION);
HANDLE h = ::FindFirstDevice(DeviceSearchType::DeviceSearchByDeviceName, L"COM2", &pdi);
DWORD error1 = GetLastError();
DWORD result = ::DeactivateDevice(pdi.hDevice);
DWORD error2 = GetLastError();
}

Display More

Festus · Jul 20th 2009

My problem is still existent. The problem is that I'm actually designing our baseboard and it will affect our baseboard design because we could use COM2 for RS232 and for RS485.

fs-support_MK · Jul 20th 2009

You are right. We have tested reactivating the serial driver and the debug line we notices that the serial driver throws an exception. There seems to be a bug in the serial driver.
We will fix this in the next kernel release.

Festus · Jul 20th 2009

Sounds good. Can you tell me when the new kernel will be available?
Another issue concerning kernel update: Please read my post in the thread Kernel update. I have trouble with kernel update in PicoMOD3.

Share