Nellcor N-180, Manual

Page: 82 / 83

A-1
APPENDIX A: COMMUNICATIONS FORMATS
Introduction
Conversation Format
Computer Format
INTRODUCTION
Serial data is output from the monitor in digital RS-232 format. The
connector is a 9-pin D-type, sub miniature, female. You use a switch to set the
baud rate to 2400, 4800, 9600, or 19,200.
Serial data output (table A-1) from the monitor can be in two forms: conver-
sation mode, where the monitor responds to inputs from an external ASCII
device, or computer mode, where the monitor provides a periodic data string
reporting saturation and pulse rate data, alarm conditions, and monitor
status. The following paragraphs describe each output mode.
CONVERSATION FORMAT
Select this format on the rear panel DIP switch by setting switch two up. At
the serial communications connector on the rear panel, connect a computer or
ASCII terminal that is ready to receive data.
When using conversation format the monitor responds by request only. At the
computer or terminal, transmit a single request; the monitor responds by
transmitting an alphanumeric string containing a data identifier and
numeric data (nnn is a numeric value between 000 and 255). For example, if
you request the current pulse rate by sending an R. The monitor responds by
sending <STX>Rnnn<CR><LF> where(nnn) is the pulse rate.
COMPUTER FORMAT
Select this format on the rear-panel DIP switch by setting switch two down.
In this format, the monitor transmits a data string every 10 seconds; or if a
parameter changes, the value is transmitted shortly thereafter the event
occurs. Parameters are pulse rate, oxygen saturation and so forth. Note that
in the following example string STX (start of transmission) and ETX (end of
transmission) are shown in hexadecimal equivalents above their positions in
the string. CHKSM stands for check sum. The string transmitted from the
monitor has this format:
(02) (03)
<STX>RnnnSnnnP000LnnnHnnnOnnnAnnnMnnnT000000Qnnn <CR><LF><CHKSM><ETX>