Hardware
isolates the digital ground from the driving ground.
2. Driving circuit of valves and pumps
The driving voltage of the valves and pumps are 12V (TTL). The circuit mainly
consists of ULN2068. In the BC-2800, the circuit can maximum drives 14 valves
and 2 pumps. The fluidic system decides which pumps or valves are to be
actually used.
1.7.2.3 Motor control block
The motor control block includes: serial communication circuit, control/drive
circuit of the sample probe mechanism, control/drive circuit of the syringe motor,
and drive/signal-detecting circuit of the position sensors.
1. Serial communication circuit
Since the CPU board requires a 3.3V power supply while the driving board
requires a 5V power supply, a photocoupler (H11L1) is needed for the purposes
of conversion and isolation.
2. Control/Drive circuit of sample probe mechanism
The control/Drive circuit of sample probe mechanism includes the control/drive
circuit of the elevator motor and that of the rotation motor. The control system of
the sample probe motor consists of a AT89S51 MCU and ADM705 WDT. The
AT89S51 also detects the signals coming from the position sensor when
controlling the motors.
A. Control/drive circuit of the elevator motor
The circuit includes the control part (a MCU system) and the drive part, as
shown in the figure below.
The MCU system provides the sequence signals for the elevator and rotation
motors and controls the position sensors, as the figure below shows. The MCU
reset signal (RST_XY) is active-high.
The drive part mainly consists of a control device (L6506), drive device (L298N)
and follow-current device (UC3610). The drive voltage is 30V. The sequence
signal and the enable signal of the drive device come from the MCU.
B. Control/drive circuit of the rotation motor
The circuit mainly consists of a control part (MCU system) and a drive part.
Refer to the previous introduction for the MCU system. The drive part is the
ULN2068B and the drive voltage is 12V. The sequence signal comes from the
MCU, as shown in the figure below.
3. Control/drive circuit of the syringe motor
The circuit mainly consists of a control part (MCU system) and a drive part.
The MCU is the P87LPC762 with built-in WDT. The MCU system executes the
aspirating and dispensing operation of the syringe and detects the signals sent
by the position transducers.
The drive part is similar to that of the elevator motor. See the block diagram
above for details.
1-12 BC-2800 Auto Hematology Analyzer (V1.0)
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