6.7
Theory of Infrared Transmission, MS Series
The Sherwood IMS Genius communicates the results of a temperature measurement via an infrared
communication link. The Genius contains an infrared transmission light-emitting diode (LED), which sends
optical impulses to the Temp-Mate. A semi-conductor optical detector in the Temp-Mate receives the optical
impulses and converts them to electrical impulses. Electronic circuitry within the Temp-Mate amplifies and
conditions the electrical impulses, sending the resulting signal to the Press-Mate for storage and display.
A magnet in the Temp-Mate closes a reed switch in the Genius when the Genius is snapped into the Temp-Mate.
When the reed switch in the Genius closes, the transmission of the temperature data is triggered. The optical
impulses emanating from the Genius are in ASCII format. The structure of the transmitted message is as
follows:
The three data frames contain identical data. If the Press-mate compares the contents of the three data frames
and determines that they are not identical, the communicated data has an error and the Press-Mate will not
accept the data. The message is transmitted at 4800 BAUD and each byte of the message has:
1 - Start Bit
8 - Data Bits
Even Parity
1 - Stop Bit
Upon receiving the optical data from the Genius, the Temp-Mate verifies that a valid, but not necessarily error-
free, transmission has occurred. If the transmission is valid, the light on the Temp-Mate flashes. After the
optical detector in the Temp-Mate has converted the optical signal into an electrical signal, other circuitry within
the Temp-Mate make it RS232C compatible and pass it on to the Press-Mate.
The Press-Mate receives the signal and determines, from its structure, that the message came from a Genius
thermometer. It verifies that the three data packets are identical and, if they are, displays and stores the
temperature information. If the three data packets are not identical, the Genius must be removed from the
Temp-Mate and replaced in the Temp-Mate so that the message is re-transmitted. When a valid, error-free
message is received by the Press-Mate, the temperature is decoded and displayed on the LED display on the
LCD and, if the printer is ON, recorded by the printer.
6.8
Theory of Operation: Genius Model 8300
Genius is an infrared sensing device adapted for use as a clinical thermometer. It senses the infrared emissions
from the tympanic membrane and calculates body temperature as a function of infrared intensity. By adding a
selectable linear offset to the calculation, Genius is able to display body temperature equivalent to an "Oral" or
"Rectal" glass mercury thermometer, or Swan-Ganz catheter in the bloodstream. Genius also functions as a
surface scanner. In this mode, it senses surface temperature variations.
Preamble
Header
Data Frame
Data Frame
Data Frame
End
6-5