baxter ARENA - Troubleshooting

11. Heparin Delivery
11.4 TROUBLESHOOTING
11.4.1 Overspeed Alarm
Refer to Figure 11-4. To ensure that the heparin pump does not
exceed its set speed, the I/O Controller board software monitors a
motor step rate clock (logic) signal from the Blood Pump
Controller board that is equivalent to 1/4th the heparin pump step
rate. In the event that a heparin pump overspeed occurs, the I/O
Controller board disables the heparin pump via a hardware line
that goes to the Blood Pump Power Board and notifies the SBC of
the alarm.
To determine if the heparin pump is running at the correct speed,
the time it takes for ten clock signals to occur is measured and
compared against a minimum time period that is set by the SBC. If
the measured period is less than the SBC set limit, an overspeed
alarm occurs. The SBC is notified of the alarm and the heparin
pump is disabled via the hardware line to the Blood Pump Power
Board.
When the heparin pump rate changes, the SBC resets the minimum
time period, and the I/O Controller board waits for the first clock
signal to restart the timer (this first clock is not counted as one of
the ten). In this way, the alarm logic is resynchronized with the
heparin pump stepper motor.
The I/O Controller board also monitors the total amount of heparin
delivered in the high-speed bolus mode. When it receives clock
signals at a rate faster than a predetermined speed, it assumes the
pump is operating in the high-speed mode. It has a high-speed
counter, which is set by the SBC. If more high-speed counts occur
than are in the counter, a high-speed alarm occurs. The SBC is
notified of the high-speed alarm and the heparin pump is disabled
via the hardware line to the Blood Pump Power Board.
11.4.2 Arm Engage/Disengage Failure
The signal from the “arm engaged/disengaged” optical sensor can
be monitored on R46 on the Blood Pump Power Board. This
sensor is also plugged into PF23 in the Blood Pump Power Board.
This signal will be low when the heparin pump is disengaged.
11.4.3 Overpressure Alarm
The end-of-stroke sensor will cause an alarm if the heparin rack
can not deliver the specified amount due to occlusion and/or an
empty syringe. The signal can be monitored on R47 on the Blood
Pump Power Board. This signal will be high and go low when an
157-1278-918 Rev A 11-9
April 2004