The Z-Drive and the Pipette Module
DSX™ System Service Manual 6-15
6.3.3 Top Level Functional Design
On starting, the Z Pipette initializes the IO ports, the variables, the Z encoder and the
communications sub-function and the program continuously checks the serial port for
incoming information. On detecting an incoming command, the program decodes it, executes
it and replies with the result as shown in Figure 6-10.
Start Initialise
Extract Command
Incoming?
Handler Exists?
Execute Command
Prepare Reply and Send it.
Repeat
NO
NO
Figure 6-10 Top Level Z/Pipette Module Program
6.3.4 Hardware Considerations
6.3.4.1. Motor Drivers Pipette and Eject
The Pipette and Eject motor drivers are similar, using the A2919, and set for 0.5 amps. The
pipette actuator is only rated for 350 mA with a software boost, and driven in quarter steps.
The Eject motor runs in half steps.
6.3.4.2. Motor Driver Z Motor
The Z Motor is driven via two National Semi Conductor H drivers ICs. These are mounted
on the Z Transition board on the Z-axis arm. The motor voltage is 24V and the H drivers
use current limiting to produce a driving current of 1.5A with boost and 0.9 Amps without
boost.
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