The Standard Patient Module - HP PageWriter XL M1705B Service Manual

The Standard
Patient Module
Note .I
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The patient module collects data from up to 13 electrodes. The
multiplexors sample the data and a calibration voltage at a 4 kHz
rate, and a successive approximation analog-to-digital converter
(ADC) digitizes the data. The patient module controller arranges
the serial data from the ADC into 24-bit serial words that it sends
to the cardiograph. The patient module electrically isolates the
electrodes from the cardiograph with opto-isolators for the data and
a transformer for the power.
The patient module receives leadwire status data from the
cardiograph for presentation on the patient module's LCD display.
A push button, 0, on the patient module allows the cardiograph
operator to remotely start a recording. Figure 5-3 is a simplified
block diagram of the patient module's circuitry.
PageWriter XLe, M1702A, does not have an LCD display or a push
button on the patient module.
The patient module connects to the cardiograph by a cable that
plugs into the cardiograph at J9. The pin assignments for the patient
module connector are described in Appendix A.
5-6 Theory of Operation