Audio Precision DCX-127 Bedienungsanleitung
DCX-127
Multifunction Module
User’s Guide
June 2000
Audio Precision PN 8211.0122
Version 1
NOTICE TO EU CUSTOMERS
This product is not updated to comply with RoHS Directive 2011/65/EU and, as of July 22, 2019, will not
be shipped to the European Union (EU). Customers may be able to purchase products from inventory
that were placed on the EU market prior to July 22, 2019 until supplies are depleted. Audio Precision is
committed to assisting with your audio measurement needs. Please contact your local AP sales
representative for further assistance or to determine if alternative product(s) are available.
Audio Precision, Inc.
PO Box 2209
Beaverton, Oregon 97075-2209
U.S. Toll Free: 1-800-231-7350
Tel: (503) 627-0832 Fax: (503) 641-8906
Email: [email protected]
Web: www.audioprecision.com
®
Copyright © 2000-2019 Audio Precision, Inc. All rights reserved.
No part of this manual may be reproduced or transmitted in any form or by any
means, electronic or mechanical, including photocopying, recording, or by any
information storage and retrieval system, without permission in writing from the
publisher
Audio Precision®, System One®, System Two™, System Two Cascade™, System
One + DSP™, System Two + DSP™, Dual Domain®, FASTTEST®, and APWIN™
are trademarks of Audio Precision, Inc.
Windows is a trademark of Microsoft Corporation.
Published by:
Printed in the United States of America
XIX0723122500
CONTENTS
Safety Information ...................v
Safety Symbols .....................vi
Disclaimer........................vi
Description........................1
Scope of This Manual..................1
Introduction ......................1
DC Voltage Measurements ...............2
Resistance Measurements ...............3
DC Voltage Outputs...................5
Digital Input ......................6
Digital Output ......................7
Program Control Outputs ..............8
Auxiliary Output Ports ................10
Installation .......................11
Mounting .......................11
Primary Power Considerations ...........11
Checking or Changing Power Line Voltage ....11
Fuse Information ...................13
Changing Fusing Arrangement ...........14
Power Switch .....................15
Proper Environment .................15
Connecting the APIB Interface............16
Operation ........................17
Panel ..........................17
Volts/Ohms Measurements .............18
DC Output 1 and 2 On/Off..............21
DC Output 1 and 2 Value ..............21
Digital Input and Output ..............22
Program Control, Gate Delay............25
Auxiliary Outputs ..................26
Specifications .....................29
DCX-127 Multifunction Module User’s Guide Page iii
Safety Information
Do NOT service or repair this product unless properly qualified.
Only a qualified technician or an authorized Audio Precision distributor
should perform servicing.
Do NOT defeat the safety ground connection. This product is
designed to operate only from a 50/60 Hz AC power source (250 Vrms
maximum) with an approved three-conductor power cord and safety
grounding. Loss of the protective grounding connection can result in
electrical shock hazard from the accessible conductive surfaces of this
product.
For continued fire hazard protection, fuses should be replaced
ONLY with the exact value and type as indicated on the rear panel and
in Section of this document. The AC voltage selector also must be set
to the same voltage as the nominal power source voltage (100, 120,
230, or 240V rms) with the appropriate fuses installed.
The International Electrotechnical Commission (IEC 1010-1)
requires that measuring circuit terminals used for voltage or current
measurement be marked to indicate their Installation Category. The
Installation Category is defined by IEC 664 and is based on the
amplitude of transient or impulse voltage that can be expected from the
AC power distribution network. This product is classified as
INSTALLATION CATEGORY II, abbreviated “CAT II” on instrument
front panels.
Do NOT substitute parts or make any modifications without the
written approval of Audio Precision. Doing so may create safety
hazards.
This product is for indoor use - pollution degree 2.
Use this equipment only for switching applications as described in
this manual.
Page iv DCX-127 Multifunction Module User’s Guide
Safety Symbols
The following symbols may be marked on the panels or covers of
equipment or modules:
WARNING! - This symbol alerts you to a potentially
hazardous condition, such as the presence of
dangerous voltage that could pose a risk of electrical
shock. Refer to the accompanying Warning Label or
Tag, and exercise extreme caution.
ATTENTION! – This symbol alerts you to important
operating considerations or a potential operating
condition that could damage equipment. Refer to the
User’s Manual or Operator’s Manual for precautionary
instructions.
FUNCTIONAL EARTH TERMINAL – This
symbol marks a terminal that is electrically
connected to a reference point of a measuring
circuit or output and is intended to be earthed for
any functional purpose other than safety.
PROTECTIVE EARTH TERMINAL – This
symbol marks a terminal that is bonded to
conductive parts of the instrument. Confirm that
this terminal is connected to an external
protective earthing system.
Disclaimer
Audio Precision cautions against using their products in a manner
not specified by the manufacturer. To do otherwise may void any
warranties, damage equipment, or pose a safety risk to personnel.
Safety Symbols Safety Information
DCX-127 Multifunction Module User’s Guide Page v
Description
Scope of This Manual
This manual serves several purposes:
§It will help you install the DCX-127 Multifunction Module. In
addition to the instrument capabilities, descriptions of all
connectors are given.
§It presents specifications of the DCX-127.
§It contains some fundamental APWIN assistance relating to the
use of the DCX-127.
Introduction
The DCX-127 Multifunction Module contains an autoranging 4-1/2
digit dc voltmeter-ohmmeter, two 20-bit programmable dc voltage
sources, 21 bits of digital I/O, and three 8-bit programmable auxiliary
output ports for device control or status indicators. Typical applications
include A/D and D/A converter testing, VCA gain control linearity, VCA
distortion, amplifier dc offset and power supply checks, power amplifier
load switching control, loudspeaker voice coil resistance
measurements, temperature measurements, and test fixture control.
The DCX-127 also provides pulses and dc levels whose timing
depend upon key software actions such as end of sweep, analyzer
channel selection, or data settling. These may be used for
synchronization and sequencing of external devices or portions of the
test system such as the triggered sine burst generator.
The DCX-127 functions include:
§DC voltage and resistance measurement from 200 mV to 500 V
and 200 W to 2 MW full scale, fully floating and guarded for
accurate measurements in the presence of large common mode
voltages. Readings can be offset and scaled by the software.
DCX-127 Multifunction Module User’s Guide Page 1
§Resistance measurements using either 4-wire or 2-wire
techniques.
§Two independently programmable bipolar floating DC voltage
outputs, each with a ±10.5 V range, 20 mV resolution and
monotonicity to 40 mV (19 bits). The software can sweep either
dc source.
§Digital input of static or low-speed parallel input, word width up
to 21 bits.
§Digital output of a parallel digital word of 21 bits.
§A simplified 8-bit program control interface that can be defined
to execute any pre-defined keystroke sequence. This can be used
to run different software procedures based upon switch closures.
All the DCX-127 output functions are controlled from APWIN
software, and all of the inputs are displayed in APWIN software and
may be displayed as bargraphs or plotted values during a sweep when
appropriate.
The DCX-127 Multifunction Module is a separate unit packaged in
a one-rack-unit high case that may be rack-mounted or used as a
bench instrument.
The following sections describe the capabilities in greater detail.
Complete specifications can be found at the end of this manual.
DC Voltage Measurements
The DCX-127 includes a 4-1/2 digit autoranging dc voltmeter-
ohmmeter. In voltage mode, the meter will automatically select among
its 200 mV, 2 V, 20 V, 200 V, or 500 V ranges for best resolution of the
measured signal. It may also be fixed on any of its ranges. The meter
has selectable reading rates of 6 or 25 readings per second. The
6/second selection provides full 4-1/2 digital resolution (20,000 counts
full scale). The 25/second selection also displays 4-1/2 digits, but the
last digit will always be either 0 or 5. Normal mode rejection and
common mode rejection also degrade by approximately a factor of
DC Voltage Measurements Description
Page 2 DCX-127 Multifunction Module User’s Guide
four when the 25/second reading rate is selected. Resolution versus
range and reading rate are shown in Table 1.
Resistance Measurements
The resistance mode operates by forcing a calibrated value of
current through the unknown resistance and measuring the consequent
voltage drop. The ohmmeter is autoranging and will select either the
200 W,2kW,20kW, 200 kW,or2MWrange depending on the value
of the unknown resistance being measured. It may also be fixed on any
range. Reading rates of 6 readings per second or 25 readings per
second may be selected. Software features also permit displaying a
computed value which is a function of resistance, using user-entered
values of offset and scale parameters. The DCX-127 input
configuration permits making these resistance measurements on either
a 2-wire or 4-wire basis.
Description Resistance Measurements
DCX-127 Multifunction Module User’s Guide Page 3
Range Resolution
6/s Rate
Resolution
25/s Rate
200 mV 10 uV 50 uV
2 V 100 uV 500 uV
20 V 1 mV 5 mV
200 V 10 mV 50muV
500 V 100 mV 500 mV
Table 1. Reading rate for various ranges
Two-wire connection
If only one pair of test leads is used, connected from the (+) and (-)
terminals of the DCX-127 to the unknown resistance, a 2-wire
measurement results. Current from the internal current source flows
through an internal resistor, through the test leads and resistance being
measured, and through another internal resistor back to the current
source. The two internal resistors are indicated schematically on the
front panel of the DCX-127. Voltage drop across these internal
resistors, produced by this current, is internally measured at the (+)
and (-) terminals. The resistance of the two test leads is thus included in
the measurement. For moderate and high values of unknown
resistance, the additional error introduced by resistance of the test leads
is usually negligible.
Resistance Measurements Description
Page 4 DCX-127 Multifunction Module User’s Guide
Vmeas
Rw
(test lead)
Rw
(test lead)
Rx
(unknown)
Iref
Icomp
+INPUT
-INPUT
600
600
-SOURCE
Figure 1.
Simplified
diagram of
2-wire
ohmmeter
operation
Four-wire (Kelvin) connection
For the highest accuracy when measuring low values of resistance,
we recommend a 4-wire measurement (Kelvin lead connection). For
this measurement, connect one pair of test leads from the two current
source connectors (marked SOURCE) to the unknown resistance.
Connected a second pair of test leads from the voltmeter input
terminals (+ and - jacks) to the unknown. Now current from the
current source does not flow through the voltmeter leads, so the
resistance of the test leads is not included in the measurement.
The resolution of the reading varies with the range and with the
reading rate as shown in Table 1 on page 3.
DC Voltage Outputs
Two independent dc voltage outputs are available at the DCX-127
front panel. Each output may be set with 20 microvolt resolution
(approximately 20 bits equivalent) to any voltage in the ±10.5000 volt
range.
Description DC Voltage Outputs
DCX-127 Multifunction Module User’s Guide Page 5
Vmeas
Rw
(test lead)
Rw
Rw
Rw
(test lead)
Rx
(unknown)
Iref
Icomp
+INPUT
-INPUT
600
600
-SOURCE
Figure 2.
Simplified
diagram of
4-wire
ohmmeter
operation
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