Technical Supplement
S- 2
0
Cuff Pressure (mmHg)
Linear Bleed Period
Cuff
Inflation
Period
Pressure
Release
Pressure
Stabilization
Time
200
150
100
50
Systolic Pressure
Mean Pressure
Diastolic
Pressure
Figure S2-1: Oscillatory Blood Pressure Measurement
S3
STACKBUS INTERCONNECT
Stackbus is the general term for the communication interconnect between the
N-3000 and the N -3100 instruments.
The internal communication bus is used for communications between the
UIF/Power Supply PCB and the Blood Pressure module. Information is
transmitted over a single PCB trace using the Arcnet (discussed in S4,
Circuit Analysis) local area network standard as the message protocol.
The external Stackbus is used for communications between the N-3000 and
the N -3100. Information is exchanged over two pins on the N-3000 docking
connector and two sockets on the N -3100 upper docking connector. As with
the internal communication bus, the Arcnet local area network standard is
used as the protocol. RS-485 drivers and receivers are used for signaling. A
proximity sensor on the N-3100 UIF PCB detects when the N-3000 is docked,
which enables the internal communication bus signals.
Access to the Stackbus is accomplished through token passing. A token
designates which station (module or instrument) has control of the Stackbus.
The token passes in a circular manner from station to station. The station
holding the token has the exclusive right to transmit onto the Stackbus, but
the right to transmit may be temporarily donated to another station to
acknowledge a transmission by the token holder. The token holder must
relinquish control of the Stackbus by passing the token to the next station on
the loop within a specified period of time. During normal operation, the right
to access the Stackbus passes from station to station in a continuous,
consistent manner.
