What Characteristics are Modifiable?

Use Workstation Configurator to specify the following characteristics for a terminal or printer port:

The XON/XOFF protocol.
The read trigger.
Block mode.
Special characters.
Echo.
Form feed.
DTC response to backspace.
Typeahead.
Printer control.
Vertical Format Control.

Each of these is described in detail on the following pages.

XON/XOFF Protocol

The XON/XOFF protocol is controlled by the device, rather than by the device driver. The driver sends data to the device in a continuous stream. If the device can no longer accept data (because of being put offline, filling its buffer, running out of paper, etc.), it sends the XOFF character to the driver. The driver then stops sending data to the device. When the device is able to accept data again, it sends the XON character to the driver and the driver resumes data transmission.

Use Workstation Configurator to specify if a timer should be started when the XOFF character is received. If a timer is started and the timer expires before the XON character is received, a message is printed on the system console stating that the device is offline. The timer duration can be specified from 1 to 255 seconds.

Block Mode

Block mode is a method of transferring data from a terminal to the computer. Instead of sending each character as it is typed, the terminal buffers a line or more of data and sends an entire block of data when the terminal user finishes entering it.

Using Workstation Configurator, the type (or types) of block mode along with the block mode alert and block trigger characters can be specified.

Read Trigger

The read trigger character is used to tell the terminal when to send characters to the driver. This character is normally the DC1 character.

Using Workstation Configurator, any character can be specified as the read trigger character. If the device requires a multiple character sequence for a read trigger, the first number minus one (n-1) characters can be sent to the device through a write and the last character can be made the read trigger character.

Special Characters

There are several characters that have special significance to the driver. These characters cause the driver to take special actions.

With Workstation Configurator, defining characters to cause a special action is possible. The characters that have special significance to the driver are as follows:

Backspace.
Cancel line.
End-of-Record.
Subsystem break.

Each of these are described in the pages that follow.

Backspace

This special function is entered by pressing [Backspace]. If enabled, backspace causes the cursor to back up one space, but it does not erase the character.

Cancel Line

This special function is entered by pressing [CTRL]-[X]. Cancel deletes the current line. The system verifies the cancellation by printing three exclamation marks (!!!), followed by a carriage return and a line feed.

End-of-Record

This function takes place during a read. When a read is issued, it has an expected length associated with it. By entering an end-of-record (EOR) character, the read can be terminated before the full number of characters has been entered. With Workstation Configurator, two types of EOR characters can be specified.

With the first type, the EOR character terminates the read, but it is not included in the data returned to the program doing the read or the actual count of characters. The read is returned with good (CCE) status.

The second type is the same as the Additional EOR specified through the FCONTROL(25) intrinsic. The character is included in both the data and the actual count of the number of bytes returned. The read is returned with a special status (a returned condition code of CCL on the read and a file system error number of FSERR 31), indicating that the read was terminated by the additional EOR character. The terminal cursor is not affected.

Subsystem Break

The subsystem break function enables you to interrupt the execution of a local program or subsystem command. The subsystem break character is invoked by pressing [CTRL]-[Y]. Using Workstation Configurator, one subsystem break character can be specified.

Echo

Echo allows terminal input to be echoed back to the terminal screen by the computer as it is received. With Workstation Configurator, the initial setting for echo (either on or off) can be specified. Whenever the terminal type is set, the initial setting for echo will take effect.




	NOTE: Applications exist that set echo before the terminal type is selected. For applications to function correctly, the program needs to select the terminal type first, and then set echo as desired (if it is different than the default

Form Feed

The form feed character is usually contained in the carriage control sent to the hard copy printer. Some hard copy printer will not accept the form feed character. Workstation Configurator can be used to replace the form feed character with a character that the hard copy printer will accept. In most instances, the form feed character is replaced with the line feed character.

Subsystem Response to Backspace

When echo is enabled, a backspace is echoed to the terminal screen which might cause some action to the data on the screen. An additional response might be required from the system for better cursor positioning. The default for backspace causes the cursor to backup one space, but it does not erase the character. Workstation Configurator can be used to specify that the character should be erased.

Typeahead

Typeahead allows the terminal user to continuously enter data without having to wait for the system to process the data and return the MPE/iX prompt (:). Typeahead echo mode determines whether input characters will be echoed to the terminal screen once or twice (the first echo occurs as the data is typed ahead; the second echo occurs when the data is used in subsequent reads). Using Workstation Configurator, typeahead can be enabled and the choice of one or two echoes of input characters can be specified.

Printer Control

When a printer acts as a spooled system printer, different people can use the printer in different ways. In order to insure that one user who changes the printer's characteristics (such as margins, tabs, or print density) does not affect the next user who does not want to use those characteristics, an initialization string can be specified.

An initialization string sets the printer to a known and repeatable state. When a device (configured as a printer) is first opened, the initialization string (up to 120 characters) is automatically sent to the printer by the driver. For spooled printers, this occurs at the beginning of every spool file sent to the printer.

Printer control functions provide control for printers. Using Workstation Configurator, an initialization string can be defined, and parameters can specify the status wait-time, the status retries, and the FOPEN wait-time. The status wait-time and status retries customize the status request protocol. FOPEN wait-time maintains a remote connection over multiple print (spool) files.

Vertical Format Control

Many line printers allow the use of Vertical Format Control (VFC). VFC instructs a printer to skip to a predetermined place on the page with certain carriage control directives instead of counting and displaying a number of blank lines and spaces.

Up to 16 VFC channels can be supported by a device with each channel representing one or more places within the vertical page. Each channel performs a standard skip function such as skip to top of next page, skip one line, skip to next quarter page, and so forth. Some serial printers allow the use of VFC through a set of character sequences. To skip to a particular VFC channel, the corresponding character sequence is sent to the device.

With Workstation Configurator, each VFC character sequence (up to 16) can be defined. When one of the VFC carriage controls is used, the driver generates the character sequence necessary to move the printer carriage to the proper channel.