Chapter 1 Overview
OsmoTECH XT Single-Sample Micro-Osmometer Service Guide
12
1.4 Electrical description
This section describes the major electrical components
in the OsmoTECH XT (see Mechanical description).
Power supply and control PCB assembly (p/n 235028)
The power supply and control PCB assembly is divided
into lower and upper sections using a metal shelf.
• The lower section contains the power entry module
(PEM), a 200W AC/DC power supply, and a fan. All
high-voltage connections are contained in the lower
section, making it safe to operate the instrument with
either the rear door and/or cover removed.
• The upper section contains the control PCB
(p/n235027PC). This board controls all of the
instrument’s low-level, time-sensitive operations, such
as the thermo-electric chamber, solenoid, barcode
scanner, and high-precision temperature probes. The
control board uses the PIC32MZ microchip
micro-controller.
Barcode scanner port
This port communicates to a 2D barcode scanner
(Diamond Technologies DSE0450-DTC0E) via 115Kbps,
1start bit, 1 stop bit, and no parity protocol. The
scanner’s presentation mode activates when an object
trips the scanner’s proximity sensor. The sensor has
built-in red illumination LEDs to help read barcodes in
low light conditions.
RS-232 driver circuits
The instrument uses three RS-232 ports:
• Communication to display PCB
• Communication to scanner
• Communication to printer
A transceiver IC handles the level translation of all three
ports.
Sample cooling assembly circuits
The sample cooling assembly circuit PCB controls the
following:
• TEC cooling block
• Two fans used to exhaust air from the power box and
remove heat from the TEC module
• Activation of the solenoid for sample nucleation
• A/D readings of the Wheatstone bridge circuits of the
sample probe and block probe
Display assembly (p/n 235022)
The display assembly functions as the main user
interface controller and provides connectivity to the USB
and Ethernet peripherals. It contains the display PCB and
color LCD screen, resistive touch element, and the USB/
Ethernet extension cables. The assembly is secured
underneath the top of the instrument’s bezel cover.
7" Color/touch LCD screen
The OsmoTECH XT instrument has a 7" WVGA
(800 x 480) LCD/touch screen built into the display
assembly. It uses a metal gasket to reduce radiated
electrical emissions. The LCD screen has a built-in
four-wire resistive touch screen overlay.
Display PCB
The display PCB contains a high-power IMX6 micro-
processor running a real-time operating system (RTOS)
from Mentor Graphics called “Nucleus.” It is used to
interact with the color/touch LCD screen and to provide
the following serial interfaces to the control PCB:
• Two USB 2.0 Type A ports
• One Ethernet port
• One USB 2.0 Type B port
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