APPENDIX A – SCI PROTOCOL AND INTERFACE
A2
RS232 PROTOCOL COMMANDS
The following commands may be issued from
a computer/terminal keyboard or other similar
communication control device. This protocol is
supported by various control systems provided by
other control system manufacturers. Standard
ASCII characters are used to create the command
strings. The SCI-MRX is not case sensitive, and
therefore does not care if capital or lower case
letters are used. Please note that spaces are not
used in any command strings.
COMMAND: Audio-Follow-Video switch
IxxxOxxx {RETURN/ENTER}
The 'I' represents INPUT and the 'O'
OUTPUT. The 'xxx' represents the one to three
digit number of the respective INPUT and
OUTPUT. Leading zeros are optional. Valid
INPUT numbers for the SCI are 1 to 128. Valid
OUTPUT numbers are 1 to 128. To generate a
TAKE command, press the RETURN/ENTER key
on the keyboard. When the SCI receives the
request and executes the change, it will respond
with an ASCII message 'OK' (unless disabled -
see "N/Y" command explanation).
COMMAND: BREAKAWAY
AxxxOxxx {RETURN/ENTER}
In this command only the requested input
Level (A) will change causing that level to
breakaway from the other levels. The 'A' could
actually be A,B,C,D,E,F,G or H. These eight
letters represent the control levels 1-8
respectively. So an "A" would correspond to
Level 1, a "D" would represent Level 4 and so
on.. The 'Oxxx' is the OUTPUT or destination
number.
COMMAND: SPLIT:
BxxxCxxxOxxx OR DxxxAxxxOxxx
In these examples, the inputs for two levels
are assigned different sources, but both will go to
the same OUTPUT or destination. Again, it is not
necessary to supply the leading zero in assigning
source or destination numbers. B17C03O04 or
B17C3O4 will both perform the same switch.
Order and number of levels does not matter.
Any combination of levels in any order is valid.
For example, D09B21A2C11O9 is a valid
sequence.
COMMAND: STATUS
Any OUTPUT’s status can be obtained by
entering the following protocol sequence:
Sxxx {RETURN/ENTER}
The 'S' represents STATUS and t he 'xxx'
represents the one to three digit ASCII number of
the OUTPUT. Any leading zeros are optional.
Press RETURN/ENTER to generate execution.
The SCI will respond with the following ASCII
message:
Output xxx, L1 xxx, L2 xxx, L3 xxx, L4 xxx, L5
xxx, L6 xxx, L7 xxx, L8 xxx
This will all print on one line on the terminal
video screen. The 'xxx' will indicate the one to
three digit ASCII number for the OUTPUT and all
the sources for LEVEL 1 to 4 or 1 to 8 in an eight
level system.
COMMAND: STATUS ALL
A global status can also be generated. This
will give the STATUS for all the active OUTPUTS.
By default, those OUTPUTS not yet addressed
will be indicated as having INPUT 01 selected.
SA {RETURN/ENTER}
The 'S' represents STATUS and the 'A'
represents ALL. As always, press the
RETURN/ENTER key to execute the command.
The SCI will respond with the following:
L1 L2 L3 L4 L5 L6 L7 L8 OUT xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx
The current INPUT STATUS for all levels of
each OUTPUT will be listed. The number of
outputs to which the SCI DIP switches are set
(see SCI DIP switch settings) will limit the number
of outputs displayed.
Anytime an invalid or incomplete message is
sent to the SCI, it will respond with an ASCII '?'
unless this response is disabled (see "N/Y"
command). This will occur for each group of
invalid characters it receives. The
RETURN/ENTER key is the delimiter between
commands. Therefore, invalid characters will not
cause a '?' response until the RETURN/ENTER
key has been sent.