Welch Allyn LC101 CO2 Module - User Manual - Manual (Page 25)

LC101 CO
2
Module OEM Implementation Manual
Welch Allyn OEM Technologies Confidential Page 25
Section 4
Host/Module Communications
The LC101 Module is a command driven slave device capable of communicating with a host
system over an asynchronous serial communication line. After the host system commands the
LC101 Module to begin transmission of CO
2
waveform and breath data packets, the Module
sends periodic packets without additional intervention by the host system. The host system must
initiate all other communication with the LC101 Module.
The LC101 Module and the host system are referred to as the “Module” and “host” in the
remainder of this section.
Communication Interface
• 9600 baud rate
• full duplex
• asynchronous using standard non return to zero (NRZ) format.
• Receive data input (RxD) is the buffered input of a 74HC14. A pull up is provided on
the Module so it can be driven by an open collector source.
• Transmit data output (TxD) is the collector of a 2N4401 transistor driven with a 10 K
base resistor from the output of a 74HC14. A weak pull up is provided to source a
CMOS load.
• Module power and communications are provided at J101.
{1 start bit 7 or 8 data bits even parity 1 stop bit}