title: vxWorks Parallel Port write() Failure
body: <p>I'm attempting to write to the parallel port for the first time using the vxWorks lptDrv driver, but a call to write() always seems to return a -1.   Here's the code I'm using:</p>
  
  <pre><code>#define PARALLEL_PORT "/lpt/0"
  
  /* Create a device for the parallel port */
  lptDevCreate(PARALLEL_PORT,0)
  
  /*open the parallel port*/
  parallelPortFD = open(PARALLEL_PORT,  O_CREAT|O_WRONLY, 0))
  
  LOCAL UINT32 watchdogBit = 0x01;
  if (write(parallelPortFD, (char*) watchdogBit, sizeof(UINT32)) == -1)
  {
      /* Always hits this block */
  }
  </code></pre>
  
  <p>Both calls to lptDevCreate and open return okay.  I currently don't have the hardware plugged into the parallel port, so that makes it difficult to test, but I don't think that would cause a write failure either.</p>
  
  <p>For some more info, I was able to call lptShow(), but I'm not sure what I'm looking at:</p>
  
  <pre><code>controlReg        = 0xff
  statusReg         = 0xff
  created           = TRUE
  autofeed          = TRUE
  inservice         = FALSE
  normalInt         = 0
  defaultInt        = 0
  retryCnt          = 1
  busyWait   (loop) = 10000
  strobeWait (loop) = 10000
  timeout    (sec)  = 1
  intLevel   (IRQ)  = 7
  </code></pre>