4BChapter One: General Information
50BIntroduction
17
Chapter One: General Information
Introduction
The MKS Baratron
®
Type DMA Absolute Pressure Transducer with a DeviceNet™ Digital
Interface is part of the MKS family of general purpose pressure transducers designed to provide
accurate, reliable, and repeatable pressure measurements in the range from 1K Torr to as low as
100 mTorr Full Scale (FS). The DMA is designed specifically to meet the needs of vacuum
process systems where environmental and process conditions are particularly demanding.
Temperature control of the DMA (45° C) and DMA (80° C) transducers minimizes the effects of
ambient or process temperature variations typically encountered in process line environments.
The DMA (45° C) controls its temperature at 45° C nominal. The DMA (80° C) transducer is
internally controlled at 80° C, thereby minimizing contamination from the process. The DMA
(Ambient) is unheated.
The DMA unit exposes only Inconel
®
to the process, permitting use with corrosive or dirty gases
and eliminating contamination of the process with transducer materials. Measurements are
independent of gas composition. Using the latest single-sided, dual-electrode Inconel transducer
design, coupled with a low impedance, fixed-frequency bridge signal conditioner, this instrument
is capable of withstanding high overpressure conditions (45 psia) with minimal or no shifts in
output over their range. The advanced bridge signal conditioning technology provides high
accuracy and operation which is extremely temperature-stable at operating pressure.
The transducer provides a digital pressure signal through the DeviceNet communications
interface, or as an analog signal through a 9-pin Type DE-9S Interface connector for direct
measurement. Output is linear and proportional to pressure. The operational settings of the DMA
unit are controlled using DeviceNet communications, which support 125, 250, and 500 Kb data
rates. A non-volatile storage device stores the user settings.
Note
Use this manual in conjunction with the Open DeviceNet Vendor Association
(ODVA) “DeviceNet Specification,” Volume I and Volume II [1, 2]; and the
SEMI
®
Standards Device Models [3, 4, 5] to obtain a complete functional
description of your device. Refer to Table 6, page 20, for a list of the documents
referenced throughout this manual.
Protection from RF interference and noisy electrical environments is increased by the use of a
metal case and internal design elements as well as surge and ESD suppression networks and RFI
filtering on all inputs and outputs.
The unit is available with a variety of fittings.
Ambient and Temperature Regulated Models are available:
The DMA (Ambient) measures pressure at ambient temperatures of 0° to 50° C (32° to 122° F).
The DMA (45° C) measures pressure at ambient temperatures of 15° to 40° C (59° to 104° F).
The DMA (80° C) measures pressure at ambient temperatures of 15° to 50° C (59° to 122° F).
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