IPosNav::StartCall

This method starts a call to get data from the Positioning and Navigation device.

Syntax

HRESULT StartCall ( hPNDevice hPN, PNData_t Call, DWORD dwPeriod );

Parameters

hPN: Handle to the Positioning and Navigation device to use.
Call: Type of data to retrieve from Positioning and Navigation device. All PNData_t calls valid for the GetData function can be used for Call.
dwPeriod: Specifies, in milliseconds, the time period between updates of data. If dwPeriod equals 0, only one call is made, and you do not need to stop the call with IPosNav::StopCall. If dwPeriod equals 1, the call can be made as rapidly as the device permits. If dwPeriod equals any other value, the StartCall method interprets that value as a period of time.

Return Values

One of the values described in the following table is returned.

Value	Description
S_OK	Success
E_FAIL	An unspecified error occurred.
E_INVALIDARG	One or more arguments are invalid.
PNAPI_E_DEVICEUNAVAILABLE	The Positioning and Navigation device is unavailable; it could be unplugged or dead.
PNAPI_E_DATAUNAVAILABLE	The data is unavailable.
PNAPI_S_CALLALREADYSTARTED	A warning that indicates a call was already started.
PNAPI_S_PERIODTOOSMALL	A Positioning and Navigation device is unable to support a call period at the requested speed.

Remarks

This method instructs the device to update its associated data structures at specified intervals. Through the GetData method, a user can obtain current data from the Positioning and Navigation device’s data structures within the position and navigation API (PNAPI) as often as needed.