Maple Systems STEPware-100 - Manual (Page 46)

OIT Key Interactive Mode Block & Network Modes
Function Keys
& Screen
Dependent
Function Keys
Displays the predefined ASCII string
or, if the Display Message feature is
enabled, the predefined message. If
the predefined ASCII string contains
control characters, they are displayed
as $. When the cursor reaches the end
of the current display line, additional
characters overwrite the character in
the last column unless the word wrap
feature is enabled, in which case, the
cursor drops to the next line of the
display.
Displays the predefined ASCII string
or, if the Display Message feature is
enabled, the predefined message. If
the predefined ASCII string contains
control characters, they are displayed
as $. If the predefined ASCII string is
longer than the remainder of the line
on the OIT’s display, only the
characters that fit are displayed.
Displaying Text from the Host Controller
The host controller can send data to the OIT’s display by simply sending printable ASCII
characters or by sending control commands and control codes.
Printable ASCII characters are immediately displayed at the OIT cursor’s current
location. The cursor is then advanced one position to the right on the current display line.
When the cursor reaches the end of the current display line, additional characters
overwrite the character in the last column and the cursor does not move, unless the word
wrap feature is enabled, in which case, the cursor drops to the next line of the display.
In addition to the standard printable ASCII characters, the host controller can also display
characters from the OIT’s extended character set. Refer to Appendix C: Extended
Character Sets for a list of the extended characters available on your OIT and the ASCII
codes the host controller should send to display them.
The host controller can control the location of data on the OIT’s display by sending
control commands and control codes. For example, to move the OIT’s cursor down to the
next line, the host controller sends the LF control code (hexadecimal 0A). To move the
OIT’s cursor to Line #2 Column #10, the host controller sends the Set Cursor Position
control command (
ESC
x 10 2 terminator). Refer to Appendix A: Control Commands and
Appendix B: Control Codes for a complete description of the available control commands
and control codes.
The OIT continuously monitors the host controller for data. Therefore, the host controller
can send data to the OIT at any time. The OIT uses a 200 byte internal storage buffer for
incoming data from the host controller. This buffer can fill up if the host controller sends
data faster that the OIT processes it. If this occurs, use software or hardware handshaking
to control the rate of data transfer. Refer to Chapter 2: OIT Configuration for information
on software and hardware handshaking.
Using a Display Variable
One display variable can be defined at any time on the OIT’s display using the Create
Display Variable control command. A display variable allows the host controller to set
aside a portion of the OIT’s display for specific data. When writing to the display
variable using the Write Display Variable control command, the host controller does not
have to worry about where the OIT’s cursor is positioned or whether the OIT operator is
in the middle of entering data. One typical use for display variables is to set aside a
location for displaying time-critical data such as error messages. Following is information
Using the OIT's Display 43
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