Agilent Technologies G1367A Reference Manual page 221

Sampling Unit Control
Needle lock, metering device valve and peristaltic pump motors are driven by
controlled pulse-width modulation in the same way as the ST L6506 (see
"Transport Unit Control"
not require precise position control. Therefore, a closed loop servo system is
not required. Commutation is done in FPGA logic. The needle lock, metering
device and valve motors use ST L6203 output drivers to deliver the higher
currents required for fast movement or high torque. The peristaltic pump
drive is built with a ST L6201 circuit.
The movement sensing of the valve motor is done by two microswitches. Two
reflection light sensors are used to detect the end positions of the needle lock
device. One photo sensor is required to detect the home position of the
metering device. All the sensors are mounted on one flex board. The flex
board and motors are connected to the sampling unit distribution board
(SUD). The SUD board is connected to the Microtiter Plate Board (MTP) via a
flat-band cable (64 pin).
Figure 38
1100 Series WS MWS Reference Manual
FPGA
Sensor Circuits
Microtiter
Safety Hall
Plate Board
Sensors (2)
(MTP)
Side Door
Sampling unit control
on page 220). The motors require fast speed but do
Needle Lock
Needle Lock
End-Position
Drive
Sensors (2)
Metering
Metering
Home-Positio
Drive
n Sensor
2A/Phase
Valve
Valve Drive
End-Position
4.5A/Phase
Sensors (2)
Peristaltic
Pump
Drive 0.15
Theory of Operation
Via
sampling
unit flex
board
Sampling Unit
Distribution Board
SLS Board
Safety Hall
Sensors (2)
Front Door
7
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