B. Braun Vista basic - Battery Operation, Alarm Circuit, and Pump Unit

System Overview
sured and the charging of the battery is interrupted for the dura-
tion of the measurement.
Battery Operation
The battery function is monitored by the following data: charge
current, discharge current and time, and self-discharge time. In
battery operation the battery function is checked during the
switch-on test. The theoretical load condition is read from the
clock module of the battery. Then the battery is connected to UBS
and the voltage is measured. If the minimum requirements are not
reached a battery alarm is activated.
Alarm Circuit
The alarm generation consists of:
- Standstill of pump due to switch- off of MS (motor circuit}
and UMOT (motor operating voltage}
- Audible alarm due to the drive of the buzzer or the ou 中
speaker via ALA- AK (control channel) or via ALA- UB
- Optical alarm. Is displayed in the LCD and a separate LED dis-
play. Additionally the set rate flashes with AAA.A.
- Staff call via the MFC staff call cable.
The user must check the optical and audible alarm during the
switch-on test. An alarm must be activated to test the staff call
alarm of the Vista basic, e.g. open pump cover during operation.
Pump Unit
The pump head is driven by a stepper motor. Each full step of the
motor is realized by 5 microsteps. The motor is driven by an FET
output stage. The function processor controls the motor with the
MS signal. A slot disc which is mounted on the pump head axle is
scanned by two light barriers (PKS1 and PKS2 signal). Thereby the
control microprocessor monitors the direction of rotation and
speed of the pump head.
The pump head position is also determined with the PKS2 signal.
The motor can therefore be accelerated during the withdrawal
phase. Thus a nearly pulse-free flow is realized in the lower deliv-
ery range (<100 ml/h). The total pump head cycles and running
time are available in the service program under history data.
Vista basic 950971 (5/04)