Solution:
Trueport or Ioland can be used in two modes of operations. In "standard" or "STREAMs" mode the Trueport/Ioland tty device resembles a standard tty device with stty and ioctl functionality. In "lite" or no "STREAMs" mode this functionality is disabled.
The ioctl function manipulates the underlying device parameters of special files. In particular, many operating characteristics of character special files may be controlled with ioctl requests.
In most cases standard/STREAMs mode is not required. An example would be a dumb terminal attached to the terminal server. In this case I/O control over the tty device is not required to be manipulated since the terminal is always using fixed communication settings.
I/O control would be most useful with modems or with applications that require full I/O control over the tty device (on some Unix versions the cu application requires this). If the application needs to dynamically change the baud rate or flow control of the Trueport/Ioland device then these ioctl changes will be changed on the terminal server's port dynamically.
Trueport standard mode is only supported when used with a Perle Jetstream terminal server or Lanstream terminal server.
Ioland streams mode is only supported when used with a Perle Iolan+ terminal server.
On most operating systems Trueport will use standard mode by default, and Ioland will use non-streams mode by default (see your Perle User Guide for configuration information).