APPENDIX 8 — VauxSerial RS-232 PORT
RS-232 Connection to the VauxSerial Port
The VauxSerial Port is designed to connect directly to any computer (or asynchronous data terminal) which
has a standard RS-232 serial port. An RS-232 Serial Cable is needed to connect the VauxSerial Port to the
Computer Serial Port. This cable is not supplied with Vaux controllers. The VauxSerial Port has a DB-25 F
(female) connector and is configured as if it were a
modem
. In RS-232 terminology,
it is wired as a DCE
(i.e. it
receives data on pin 2, and transmits data on pin 3 of its DB-25 F connector). If you currently have a cable
for connecting your computer to a
modem
, it will likely work with your VauxSerial Port. Vaux also offers
optional Serial Cables for IBM PC-compatible and Macintosh computers. You may also choose to wire your
own cable — see later sections. Connection of
Hardware Handshaking
lines is recommended, and will be
necessary for large amounts of communications traffic (e.g. upload/download of data blocks).
Not all RS-232 Serial Ports are the same, and some may require certain pins to be asserted before the port
becomes active. If your cable is not providing Hardware Handshake signals from the VauxSerial port, and
your computer's Serial Port is requiring a handshake input (on CTS, DSR, and/or DCD), you will likely need
to change your computer's Serial Port configuration to ignore these lines. The Vaux end does not need
special treatment —
the VauxSerial handshake inputs (from RTS and DTR) may be left unconnected and they will
assume an always true state
(effectively, it will presume that an infinitely-large receive buffer exists at the
computer end of the cable).
The Controller communicates at 9600 baud (bits-per-second) using 8 bits of data, no parity, and one stop bit.
The Serial
Port on the controlling computer or terminal must be configured according to its manufacturer's
instructions. Information transfer between the controlling computer and the Vaux system is in the Vaux
Protocol™ format — a Vaux-defined command language. The Vaux Protocol format is comprised of various
command and message information streams, as defined in the
Vaux Protocol Specification
document.
VauxSerial PCI Port (RS-232 Interface) (DB-25 F Connector):
Pin
Description
Signal Direction
Vaux Use
1
Frame Ground
—
[not used]
2
TXD (Transmit Data)
Computer —> Vaux
Data In
3
RXD (Receive Data)
Computer <— Vaux
Data Out
4
RTS (Request To Send)
Computer —> Vaux
Handshake In*
5
CTS (Clear To Send)
Computer <— Vaux
Handshake Out**
6
DSR (Data Set Ready)
Computer <— Vaux
Handshake Out**
7
Signal Ground
—
Signal Ground
8
DCD (Data Carrier Detect)
Computer <— Vaux
Handshake Out**
20
DTR (Data Terminal Ready)
Computer —> Vaux
Handshake In*
22
RI (Ring Indicator)
Computer <— Vaux
[not used]
Note:• TXD, RXD, and Signal Ground are mandatory connections.
** At least one of the Vaux Handshake Out signals (CTS, DSR, DCD) should be
connected to, and sensed by, your computer, if Hardware Handshaking is used.
* At least one of the Vaux Handshake In signals (RTS, DTR) should be
connected to, and driven by, your computer, if Hardware Handshaking is used.
•All lines listed as not used, and other lines not listed, are not
connected (to anything) in the VauxSerial interface.
• The shield rim (the "D") is connected to signal ground.
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