User guide

LongView Installer/User Guide
24
What signals and data rates does LongView’s
serial port support and how do I configure it?
The serial port on LongView is intended to extend
a standard PC COM port. A COM port uses serial
asynchronous data (i.e. no clock signal) along
with some handshake lines. LongView provides
Transmit Data (TD), Receive Data (RD), Request-
to-Send (RTS), Clear-to-Send (CTS), Data
Terminal Ready (DTR), and Data Set Ready
(DSR).
LongView’s serial port is specified for
applications up to 19.2Kbps, but it may work at
rates up to twice that, depending upon your PC’s
COM port and your serial device. TD and RD are
sampled at a high rate at one end and recreated at
the other end with a slight amount of jitter. If
your equipment is tolerant of jitter, you may be
able to use LongView at rates higher than the
specified 19.2Kbps. There are no configuration
straps or switches for data rate. Just connect your
equipment as if you were connecting your serial
device directly to the COM port.
The only COM port signals not supported by
LongView are Data Carrier Detect (DCD) and
Ring Indicator (RI), which are seldom used.
Consult the manufacturer of your serial device
and communication software to determine if you
need DCD or RI. If so, you may be able to use
LongView’s extension of CTS or DSR in its place
by building an adaptor at each end (one between
the computer and the LongView Transmitter, the
other between the LongView Receiver and your
device). A similar adaptor is required between
the LongView Receiver and the serial device.