2
SCI generated responses can be disabled by
pressing a single key. The command is:
N
This will prevent all SCI responses. No carriage
return is required. At any time, the responses can be
resumed. The command is:
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 totally
discarded. In this way, it is possible to tailor a program
to allow only a status response but inhibit all other SCI
messages.
Any time a wrong key is accidentally pressed or a
command needs to be changed, the current command
can be cancelled by pressing the SPACEBAR. This is
always true as long as the RETURN/ENTER key has
not yet been pressed. All keys pressed 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 first before
beginning any responses. This process assures the
fastest handling of a change request.
Version information of the SCI162’s firmware can
be displayed. The command is:
V
The SCI will respond with the following text:
Sigma Electronics Copyright 20XX
SCI-162 firmware version X.XX {Month Day Year}
RS422 CONTROL
Unlike RS232, RS422 allows for multiple devices to
be connected to a computer/terminal at the same time.
In order for the computer/terminal to communicate with
a device in RS422, it must first tell the device to listen.
This is the purpose of the logic address. The SCI has
four DIP switches reserved for setting the device's logic
address. Valid addresses for the SCI are 01-15 (an
address of 00 indicates that RS-232 is being used).
The format for protocols is identical to that of
RS232 with one exception. Any instruction (including
XON/XOFF) must be preceded by the following:
/xx
The slash is the precursor, and the 'xx' is the logic
address of the device. This is ALWAYS a TWO DIGIT
NUMBER.
By way of example, to generate a switch, the
sequence would be as follows:
/xxIxxOxx
{RETURN/ENTER}
Where the first 'xx' is the SCI's logic address (two
digits), the second 'xx' is the one or two digit INPUT
number and the third 'xx' is the one or two digit
OUTPUT number.
The SCI supports the XON/XOFF protocol. This is
a method, through software, of halting and resuming
transmission of data. The XOFF is activated by
holding the Control key and pressing 'S' (CTRL-S).
This will halt data transmission. XON is activated by
holding the Control key and pressing 'Q' (CTRL-Q).
This will resume transmission. Incoming commands
are still executed during an XOFF. It is the responses
generated by the SCI that are not sent. They are held
in a message buffer until an XON is received. At that
time, all pending responses are sent out the serial port
in the same sequence in which they were received.
Like the CANCEL command, XON and XOFF are
automatic and do not require the RETURN/ENTER key
to be pressed.
