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Any controller that is capable of sending and
receiving ASCII characters through a serial port can potentially communicate to
a MAP, MAP450D, MicroOIT or OIT Family terminal. These terminals communicate
with controllers by sending and receiving simple ASCII character
strings.
These terminals accept:
- Printable ASCII Characters – which
immediately display on the terminal
- Control Codes – non-printable ASCII
characters which directly affect the terminal's display.
- Control Commands – special combinations of
printable and non-printable ASCII characters. Control commands allow the
controller to modify the terminal's configuration, display information on the
terminal and request information from the terminal.
These terminals send:
- Control Command Responses – special
combinations of printable and non-printable ASCII characters sent in response
to Control Commands received from the controller.
- User-Definable ASCII Strings – up to 40
printable & non-printable ASCII characters. Each of the terminal's function
keys can be programmed with one or two of these strings.
- Printable ASCII Characters – all of the
terminal's keys (except function keys) send individual ASCII characters to the
controller when pressed.
In addition to these powerful communication
features, all of these terminals offer internal storage for up to 500
user-definable messages and two user-definable ASCII strings for each function
key.
By storing common messages in the terminal, you
can reduce the controller's work load. The controller can display a stored
message by simply sending the Display Message control command; to write a
message directly to the terminal's display, the controller has to send the
entire message.
Each of the terminal's function keys can be
programmed with one or two user-definable ASCII strings of up to 40 ASCII
characters (printable and non-printable). Programming two strings allows the
function key to:
- simulate a momentary switch
- simulate a push on/off switch
- perform a second function if the function key
is pressed with the Shift key. For example, function key sends "A" while
function + shift sends "B".
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Operating Modes
These terminals can operate in three
different modes: Interactive, Block and Network. These modes affect how the
terminal sends data to and receives data from the controller. |
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Interactive Mode
In Interactive mode,
the terminal immediately sends data to the controller. For example, pressing
the terminal's 1 key sends the ASCII character 1 to the controller and pressing
a function key sends the user-defined ASCII string(s). When the Local Echo
feature is enabled, the ASCII characters sent to the controller are also
displayed on the terminal. Interactive mode is typically used in applications
that require simple one-key responses from the terminal.
Block Mode
In Block Mode, the terminal
sends data to the terminal's display and to a Keyboard Input Buffer where it is
stored until the terminal's Enter key is pressed. This allows the terminal
operator to make changes to the data before sending it to the controller. When
the Block Echo feature is disabled, asterisks are sent to the terminal's
display instead of the data.
Network Mode
Network mode allows up to
255 terminals to be networked to a single controller. The actual number of
terminals that can be networked may be less depending on the loading
characteristics of the terminals, the controller and the communications wiring.
All communications are initiated by the controller, which operates as the
network master, polling the terminals for responses. Each terminal on the
network has a unique network address. To communicate with a particular
terminal, the controller sends that terminal's network address in hexadecimal
as two ASCII characters. The controller can then communicate with the terminal
as in Block mode. To close communications with the terminal, the controller
must send a line terminator. The line terminator alerts all of the terminals on
the network that a new communication session is about to begin and that the
next two characters sent will be a terminals network address. The controller
can send an identical message to all of the terminals on the network by using
the global broadcast address of "00". The terminals do not return a response to
the controller when the global address is used; this prevents the terminals
from corrupting each other's messages by trying to talk at the same
time.
Settings
Handshaking
This setting determines the
type of handshaking that is used between the terminal and the controller.
Handshaking allows the controller to regulate when the terminal sends
information; preventing the terminal from overwriting the controller's serial
buffer or vice versa. Options include: software (Xon/Xoff), hardware (RTS/CTS),
both and none.
Line Terminator
This setting determines
which ASCII character is used for the line terminator. Options include: CR, LF,
CR/LF and ETX.
Delayed Linefeed
This setting determines
whether the terminal executes a linefeed (LF) immediately or when the next
character is received. When Delayed Linefeed is enabled the terminal does not
execute an LF received from the controller until the next character is
received. When an LF is executed, the cursor in the terminal's display is moved
to the next line. If the cursor is already on the last line of the display, the
existing display lines are scrolled up one line with the top line disappearing.
Enabling Delayed Linefeed helps make sure that the terminal operator has a
chance to read the information before it scrolls off the display.
Append Linefeed
This setting determines
whether a linefeed (LF) is appended to all carriage returns (CR) received from
the controller. When Append Linefeed is enabled the terminal appends an LF to
every CR received from the controller. The LF causes the cursor in the
terminals display to move to the next line. This feature is useful when using
controllers which can send ASCII strings followed by a CR, but not an LF.
Without Append Linefeed enabled, these controllers would be forced to display
characters on only one line of the terminal's display.
Turn-Around Delay
This setting
determines the amount of time the terminal waits to respond after receiving a
command from the controller. Use this setting if the controller needs time to
prepare for the terminal's response. Options include: no delay, 50 msec, 100
msec and 250 msec.
Wrap Around Text
This setting determines
whether the terminal automatically wraps text to the beginning of the next line
when it reaches the end of the current line.
Cursor Type
This setting determines the
type of cursor used in the terminal's display. Options include: underline and
no cursor.
Tab Width
This setting determines how
many spaces the terminal moves the cursor when an HT is received from the
controller. Options include: 1 space, 4 spaces, and 8 spaces.
Control Codes
Control Codes are non-printable ASCII characters
sent from the controller to the terminal which cause the terminal to perform
specific functions.
| Control
Code |
Description |
| ENQ |
Returns six ASCII digits representing the
terminal's current product model, version, revision and serial interface
type. |
| BEL |
Sounds a 1/2 second warning beep. |
| BS |
Moves the cursor one character position to
the left in the current display line. The BS is non-destructive meaning that no
characters are removed from the display. If the cursor is at the beginning of
the line, the BS is ignored. |
| HT |
Moves the cursor to the beginning of the next
tab field. If the cursor is at the end of the current display line, the HT is
ignored. |
| LF |
Moves the cursor to the beginning of the next
display line. If the cursor is on line #1, the cursor moves to line #2 without
disturbing the contents of either line. If the cursor is on the last line, all
lines move up one line clearing the last line for new input. |
| VT |
Moves the cursor to the beginning of the
previous display line. If the cursor is on line #2 or lower, the cursor moves
to the beginning of the previous line without disturbing the contents of any
line. If the cursor is on the top line, all lines scroll down one line clearing
the top line for new input. |
| FF |
Clears the entire display and moves the
cursor to the beginning of line #1. |
| CR |
Moves the cursor to the beginning of the
current display line without disturbing the contents of the line. |
| XON |
Resumes terminal transmission previously
halted by an XOFF. |
| XOFF |
Halts terminal transmission. |
| CAN |
Erases the characters from the cursor to the
end of the current display line. |
Control Commands
Control Commands are special combinations of ASCII
characters sent from the controller to the terminal. They allow the controller
to:
modify the terminal's configuration
display information on the terminal
and request
information from the terminal.
| Control Command Format |
| ESC |
Command Letter |
Command Data |
Command Terminator (STX) or
Line
Terminator (CR,LF,CR/LF,ETX) |
If the control command requires a response from
the terminal, the terminal immediately responds with any requested data and the
line terminator.
| Control Command Response |
| Command Data |
Line Terminator (CR,LF,CR/LF,ETX) |
Configuration Control Commands
| Control
Command |
Command
Letter |
Description |
| Set LCD Viewing Angle or Brightness
Level |
a |
Allows the controller to control the viewing
angle of the LCD or the display brightness of the VFD. |
| Save Configuration Parameters |
b |
Saves the terminal's current setup
permanently into the Flash PROM. The saved parameters become the defaults used
at power-up. |
| Request Configuration Data |
c |
Returns six ASCII digits representing the
terminal's current product model, version, revision and serial interface
type. |
| Display and Cursor Format Control |
d |
Allows the controller to enable or disable
the terminal's cursor and delayed line feed. |
| Display Format Control |
f |
Allows the controller to enable or disable
block echo during Block mode and local echo during Interactive
mode. |
| Keyboard Control |
k |
Allows the controller to enable or disable
keyboard entry from the terminal, the keyboard's audible click, and local
setup. |
| Set Turn-Around Delay |
t |
Allows the controller to change the delay
between the time the terminal receives a command requesting data and the
terminal's response. |
| Set Tab Character Width |
z |
Allows the controller to set the width of
each "tab stop" used by the HT control code. |
| Set Communications Parameters |
B |
Allows the controller to change the
terminal's baud rate, parity and data bits. |
| Enable Handshaking |
H |
Allows the controller to enable or disable
hardware and software handshaking. |
| Set Operating Mode |
M |
Allows the controller to change the
terminal's operating mode and network address. |
| Set Line Terminator |
T |
Allows the controller to change the line
terminator. |
General Purpose Control Commands
| Control
Command |
Command
Letter |
Description |
| Echo Back Text |
e |
Causes the terminal to echo back the ASCII
characters sent. |
| Sound Bell |
g |
Allows the controller to sound the terminal's
transducer. |
| Display Message |
m |
Displays one of the 500 user-definable
messages starting at the current cursor position. |
| Clear Output Buffer |
o |
Clears the contents of the terminal's
Keyboard Input Buffer and Keyboard Output Buffer when the terminal is in Block
or Network modes. |
| Poll OIT Buffer |
p |
Allows the controller to retrieve the
contents of the Keyboard Output Buffer when in Network mode. |
| Retransmit Last Keyboard Buffer |
r |
Allows the controller to retrieve the
previous contents of the Keyboard Output Buffer when in Block or Network
modes. |
| Function Key Control |
K |
Allows the controller to enable or disable
one or all global function keys. |
| Screen Function Key Control |
L |
Allows the controller to enable or disable
one or all screen-dependent function keys. |
| Request Keyboard Buffer Status |
? |
Allows the controller to determine the status
of the terminal's Keyboard Input Buffer. |
| Enable Block Mode |
{ |
Allows the controller to dynamically change
from Interactive to Block mode. |
| Disable Block Mode |
} |
Allows the controller to dynamically change
from Block to Interactive mode. |
Display Control Commands
| Control
Command |
Command
Letter |
Description |
| Read Display Variable |
u |
Allows the controller to retrieve the
contents of a display variable. |
| Write Display Variable |
v |
Allows the controller to change the contents
of a display variable. |
| Create Display Variable |
w |
Allows the controller to create a display
variable at the current cursor position. The area allocated for the display
variable is cleared and the cursor is placed to the right of the
field. |
| Set Cursor Position |
x |
Allows the controller to move the cursor to
any position within the display without affecting the display
contents. |
| Read Cursor Position |
y |
Allows the controller to determine the
cursor's current position. |
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