Network Variable Engine in application started in autorun

Question

Using CVI 2009 SP1 I developed an application that uses Network Variable Engine:
At the beginning of main I wait in a do-loop until the Variable Engine is running
t_start = Timer();
do {
CNVVariableEngineIsRunning(&running);
if (!running) {
t_rem = 20.0 - (Timer() - t_start);
if (t_rem > 0.) Sleep(100); //100 ms
} while (!running && (t_rem > 0.));
 Then I create a buffered subscriber, previously checking that the process exists and is running
CNVProcessExists (processName, &exists);
if (!exists) {
CNVNewProcess (processName);
CNVProcessIsRunning (processName, &isRunning);
if (!isRunning) {
CNVStartProcess (processName);
CNVCreateBufferedWriter (NetVarPathname, ConnTransferredCallback,
ConnStatusCallback, NULL, 10, 10000, 0, bufferedWriter);
This application works perfectly when I launch it as standalone application.
But If I launch it at the Windows boot time through Start >> Programs >> Startup, CNVCreateBufferedWriter( ) returns -6337 (The network variable process was not found or is not responding).
Does CNVStartProcess( ) need a delay time?
How can I avoid this annoying error?
Vix
In claris non fit interpretatio
Using LV 2013 SP1 on Win 7 64bit
Using LV 8.2.1 on WinXP SP3
Using CVI 2012 SP1 on Win 7 64bit, WinXP and WinXP Embedded
Using CVI 6.0 on Win2k, WinXP and WinXP Embedded

Answer 1

CNVProcessIsRunning only checks if the process is configured to run when the Variable Engine is started...
I think this advice should be added to the function help.
But in cases where this function is called during system startup, it is unreliable because the Variable Engine could still have not loaded...
As I write in the first message, the first function I call in my application is CNVVariableEngineIsRunning( ), then I wait until it returns "is running". Why does the NVE could still have not loaded after "is running" has been returned?
A workaround for this problem and correct indicator of the availability of the process is to programmatically browse to the process:
CNVBrowser browser;
CNVCreateBrowser(&browser);
CNVBrowse("\\\\localhost\\your-process-name");
CNVDisposeBrowser(browser);
If CNVBrowse succeeds, then the process is running. Please let us know if you run into issues with this workaround.
Done. After this, I've never seen the error anymore... but I'll check again.
Vix
In claris non fit interpretatio
Using LV 2013 SP1 on Win 7 64bit
Using LV 8.2.1 on WinXP SP3
Using CVI 2012 SP1 on Win 7 64bit, WinXP and WinXP Embedded
Using CVI 6.0 on Win2k, WinXP and WinXP Embedded