PrintfNoPoll

Sends formatted output to a device without polling for errors.

Syntax

virtual HRESULT PrintfNoPoll(const CString strFormat [, argument] ...) abstract;

Parameters

strFormat

[in] String describing the format for arguments. See the topic I/O Format Specifiers for Write Operations for details.

argument

[in] Optional arguments interpreted by the format string.

Return value

Returns S_OK if successful, otherwise a failure HRESULT.

Remarks

This function behaves identically to Printf except that the device is not polled for errors after the data is sent. This can be useful in cases where a query string is sent to the device and a separate function will be executed to read the results. Were Printf used in such a situation instead of PrintfNoPoll, the error polling command would attempt to write to the device again — before the results of the initial query could be read.

Example

The following example demonstrates use of the PrintfNoPoll function. Note that the topic I/O Format Specifiers for Write Operations has many more examples of format strings that can be used with PrintfNoPoll.

STDMETHODIMP Acme4321::IAcme4321_Configure(long Channel, long* Count)
{
  HRESULT hr = S_OK;

  // Send query command to device, without polling for errors
  hr = io.PrintfNoPoll(_T("TRIG:COUNT? %d"), Channel);
  if (SUCCEEDED(hr))
  {

  // ... other logic

    hr = io.ReadNumber(Count);
  }

  return hr;
}