APPENDIX A – SCI PROTOCOL AND INTERFACE
A3
COMMAND: MATRIX SETUP REQUEST
The input/output matrix setup information of
the system can be displayed. To do this, send the
following command:
? {RETURN/ENTER}
The SCI will respond with the following
message:
AVAILABLE OUTPUTS ARE: xxx
AVAILABLE INPUTS ARE: xxx
where 'xxx' is the number of inputs and
outputs set at the SCI DIP switches.
COMMAND: DISABLE RESPONSE
Responses generated by the SCI can be
disabled with the following command. The
command is:
CTRL-N
This will prevent all SCI responses. No
carriage return is required.
COMMAND: ENABLE RESPONSE
At any time, the responses can be resumed.
The command is:
CTRL-Y
Again, no carriage return is needed. Please
note this process differs from the XON/XOFF
routine. In that case, the responses are held in a
buffer and then all pending messages are sent
upon receiving the XON command. In this case,
the messages are simply discarded and no record
of them is kept. In this way, it is possible to tailor a
program to allow only a status response but inhibit
all other SCI messages.
COMMAND: CLEAR ENTRY
Whenever a wrong key is accidentally
pressed or a command needs to be changed, the
current command can be cleared by pressing the
SPACEBAR. This is always true as long as the
RETURN/ENTER key has not yet been pressed.
All keystrokes made since the last entry of the
RETURN/ENTER key will be erased. The
CANCEL command is automatic and does not
require the RETURN/ENTER key to be pressed.
The format is:
{SPACEBAR}
The SCI will respond by sending a carriage
return and linefeed to move the cursor on the
screen to the beginning of the next line.
The SCI always gives priority to commands
over responses. All commands are executed
before any responses are sent. This assures the
fastest processing of a change request.
COMMAND: DISABLE CONTROL PANELS
It is possible to disable the remote control
panels and give exclusive attention to the serial
port for improved response time to incoming serial
commands. To halt the scanning of panels press:
PD {CARRIAGE RETURN}
The response is "Panels Inactive." This will
cause the polling and updating of any remote
panels to stop. This command is especially useful
to improve SCI efficiency in systems where
control panels are not used. Also, this command
can be used to temporarily disable the panel
scan, execute time critical serial transactions, and
then re-enable the panel scan with the next
command.
COMMAND: ENABLE CONTROL PANELS
To re-enable the control panel scan routines
press:
PE {CARRIAGE RETURN}
The response is "Panels Active." Now the
SCI is fully functional again and the panels will be
updated and polled as before. Careful tailoring of
programming will allow maximum efficiency in
executing serial commands in those applications
where execution time is especially critical.
COMMAND: CONTROL PANEL STATUS
The current control panel status can be
determined by pressing:
PS {CARRIAGE RETURN}
This will yield the response of Panels Active
or Panels Inactive depending on the current
state.