Measurement Computing CIO-DAS1401/12 User manual

Artisan Technology Group is your source for quality
new and certied-used/pre-owned equipment
• FAST SHIPPING AND
DELIVERY
• TENS OF THOUSANDS OF
IN-STOCK ITEMS
• EQUIPMENT DEMOS
• HUNDREDS OF
MANUFACTURERS
SUPPORTED
• LEASING/MONTHLY
RENTALS
• ITAR CERTIFIED
SECURE ASSET SOLUTIONS
SERVICE CENTER REPAIRS
Experienced engineers and technicians on staff
at our full-service, in-house repair center
WE BUY USED EQUIPMENT
Sell your excess, underutilized, and idle used equipment
We also offer credit for buy-backs and trade-ins
www.artisantg.com/WeBuyEquipment
REMOTE INSPECTION
Remotely inspect equipment before purchasing with
our interactive website at www.instraview.com
LOOKING FOR MORE INFORMATION?
Visit us on the web at www.artisantg.com for more
information on price quotations, drivers, technical
specications, manuals, and documentation
Contact us: (888) 88-SOURCE | [e-mail] | www.artisantg.com
SM
View
Instra

CIO-DAS1401/12,
CIO-DAS1402/12,
CIO-DAS1402/16
Data Acquisition & Control Boards
User’s Manual
Revision 7
November, 2000
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com

LIFETIME WARRANTY
Every hardware product manufactured by Measurement Computing Corp. is warranted against defects in materials or workmanship for
the life of the product, to the original purchaser. Any products found to be defective will be repaired or replaced promptly.
LIFETIME HARSH ENVIRONMENT WARRANTYTM
Any Measurement Computing Corp. product which is damaged due to misuse may be replaced for only 50% of the current price. I/O
boards face some harsh environments, some harsher than the boards are designed to withstand. When that happens, just return the
board with an order for its replacement at only 50% of the list price. Measurement Computing Corp. does not need to profit from your
misfortune. By the way, we will honor this warranty for any other manufacture’s board that we have a replacement for!
30 DAY MONEY-BACK GUARANTEE
Any Measurement Computing Corp. product may be returned within 30 days of purchase for a full refund of the price paid for the
product being returned. If you are not satisfied, or chose the wrong product by mistake, you do not have to keep it. Please call for a
RMA number first. No credits or returns accepted without a copy of the original invoice. Some software products are subject to a
repackaging fee.
These warranties are in lieu of all other warranties, expressed or implied, including any implied warranty of merchantability or fit-
ness for a particular application. The remedies provided herein are the buyer’s sole and exclusive remedies. Neither Measurement
Computing Corp., nor its employees shall be liable for any direct or indirect, special, incidental or consequential damage arising
from the use of its products, even if Measurement Computing Corp. has been notified in advance of the possibility of such damages.
MEGA-FIFO, the CIO prefix to data acquisition board model numbers, the PCM prefix to data acquisition board model numbers,
PCM-DAS08, PCM-D24C3, PCM-DAC02, PCM-COM422, PCM-COM485, PCM-DMM, PCM-DAS16D/12, PCM-DAS16S/12,
PCM-DAS16D/16, PCM-DAS16S/16, PCI-DAS6402/16, Universal Library,InstaCal, Harsh Environment Warranty and Measure-
ment Computing Corp. are registered trademarks of Measurement Computing Corp.
IBM, PC, and PC/AT are trademarks of International Business Machines Corp. Windows is a trademark of Microsoft Corp. All other
trademarks are the property of their respective owners.
Information furnished by Measurement Computing Corp. is believed to be accurate and reliable. However, no responsibility is
assumed by Measurement Computing Corp. neither for its use; nor for any infringements of patents or other rights of third parties,
which may result from its use. No license is granted by implication or otherwise under any patent or copyrights of Measurement Com-
puting Corp.
All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form by any
means, electronic, mechanical, by photocopying, recording or otherwise without the prior written permission of Measurement Comput-
ing Corp.
Notice
Measurement Computing Corp. does not authorize any Measurement Computing Corp. product for use in life sup-
port systems and/or devices without the written approval of the President of Measurement Computing Corp. Life
support devices/systems are devices or systems which, a) are intended for surgical implantation into the body, or
b) support or sustain life and whose failure to perform can be reasonably expected to result in injury. Measure-
ment Computing Corp. products are not designed with the components required, and are not subject to the test-
ing required to ensure a level of reliability suitable for the treatment and diagnosis of people.
©Copyright 2000,Measurement Computing Corporation
HM CIO-DAS140#_1#.lwp
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com

Table of Contents
239.2 CIO-DAS1402/16 ...................................................................... 229.1 CIO-DAS1401/12 and CIO-DAS1402/12 ................................................... 22
9 SPECIFICATIONS ........................................................................ 218.2 LOW-PASS FILTERS .................................................................. 208.1 VOLTAGE DIVIDERS ................................................................. 20
8 ANALOG ELECTRONICS ................................................................. 197.2 CALIBRATING THE A/D CONVERTERS ................................................. 197.1 REQUIRED EQUIPMENT .............................................................. 19
7 CALIBRATION AND TEST ................................................................ 196.2.13 Burst Status Register .............................................................. 196.2.12 DAS1400 Mode Enable Register .................................................... 186.2.11 Burst Mode Enable Register ........................................................ 186.2.10 Convert Disable Register .......................................................... 186.2.9 Pacer Clock Data & Control Registers ................................................ 176.2.8 Programmable Gain Control Register / Burst Rate ....................................... 166.2.7 Pacer Clock Control Register ........................................................ 156.2.6 DMA, Interrupt & Trigger Control .................................................... 156.2.5 Status Registers ................................................................... 146.2.4 Four-Bit Digital I/O Registers ....................................................... 146.2.3 Channel MUX Scan Limits Register ................................................... 146.2.2 A/D Data & Channel Registers (CIO-DAS1402/16) ...................................... 136.2.1 A/D Data & Channel Registers (CIO-DAS140#/12 ....................................... 126.2 CONTROL & DATA REGISTERS ....................................................... 126.1 INTRODUCTION ..................................................................... 12
6 REGISTER ARCHITECTURE .............................................................. 115.3.7 Isolated Grounds / Differential Inputs ................................................. 115.3.6 Isolated Grounds / Single-Ended Inputs ................................................ 105.3.5 Common Mode Voltage, Greater Than +/-10V ......................................... 95.3.4 Common Mode Voltage, Less than +/-10V / Differential Inputs ............................. 95.3.3 Common Mode Voltage Less Than +/-10V / Single-Ended Inputs ............................ 95.3.2 Common Ground / Differential Inputs .................................................. 85.3.1 Common Ground / Single-Ended Inputs ................................................. 85.3 WIRING CONFIGURATIONS ............................................................ 75.2.2 Systems with Common Grounds ....................................................... 75.2.1 Ground Testing .................................................................... 75.2 SYSTEM GROUNDS and ISOLATION .................................................... 55.1.2 Differential Inputs .................................................................. 55.1.1 Single-Ended Inputs ................................................................ 55.1 ANALOG INPUTS ..................................................................... 5
5 ANALOG CONNECTIONS ................................................................. 4
4 CONNECTOR PINOUTS ................................................................... 33.8 BURST MODE GENERATOR ............................................................ 33.7 AUXILIARY TRIGGER ................................................................. 33.6 PACER EDGE SELECT ................................................................. 23.5 BIPOLAR/UNIPOLAR MODE SELECTION ................................................ 23.4 8/16 CHANNEL SELECT ................................................................ 23.3 1/10 MHz XTAL JUMPER ............................................................... 23.2 DMA LEVEL SELECT .................................................................. 13.1 BASE ADDRESS SWITCHES ............................................................ 1
3 HARDWARE INSTALLATION .............................................................. 1
2 SOFTWARE INSTALLATION .............................................................. 1
1 INTRODUCTION ..........................................................................
i
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com

This page is blank
ii
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com

1 INTRODUCTION
The installation and operation of all three of the CIO-DAS1400 series boards is very similar. Throughout this manual we use
CIO-DAS1400 as a generic designation for the CIO-DAS1401/12, CIO-DAS1402/12 and CIO-DAS1402/16. When required due to
the differences in the boards, the specific board name is used.
The CIO-DAS1400 is easy to use. This manual will help you quickly and easily setup, install and test your board. If you are unfamiliar
or uncomfortable with board installation, please refer to your computer’s documentation.
We recommend you perform the software installation described in section 2 prior to installing the board. InstaCalTM will show you
how to set the switches and jumpers on the board before installing the board.
2 SOFTWARE INSTALLATION
The board has a variety of switches and jumpers to set before installing the board in your computer. By far the simplest way to
configure your board is to use the InstaCalTM program provided as part of your software package. InstaCalTM will show you all
available options, how to configure the various switches and jumpers to match your application requirements, and will create a
configuration file that your application software (and the Universal Library) will refer to so the software you use will automatically
know the exact configuration of the board.
Please refer to the Software Installation Manual regarding the installation and operation of InstaCalTM. The following hard copy
information is provided as a matter of completeness, and will allow you to set the hardware configuration of the board if you do not
have immediate access to InstaCalTM and/or your computer.
3 HARDWARE INSTALLATION
You must set switches and jumpers before installing the board in your computer. The simplest way to configure your board is to use
the InstaCalTM program provided as part of your software package.
The following information is provided to allow you to set the hardware configuration of the CIO-DAS1400 board if you do not have
immediate access to InstaCalTM and/or your computer.
3.1 BASE ADDRESS SWITCHES
Unless there is already a board in your system using address 300 hex
(768 decimal), leave the switches as they are set at the factory.
In the example shown in Figure 3-1, the CIO-DAS1400 is set at base
address 300 hex.
Note: Wait State Enable is typically not required. Leave the WAIT
EN switch in the UP (not enabled) position.
Figure 3-1. Base Address Switches
-1-
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com

3.2 DMA LEVEL SELECT
DMA level 1 or 3 may be selected. The default level is level 1 (Figure 3-2).
There are other boards that use DMA levels. Some network boards do and
so do some IEEE-488 interface boards. Check to see if you have other
boards in your computer that use DMA channels 1 or 3.
Figure 3-2. DMA Level Select Switch
3.3 1/10 MHz XTAL JUMPER
The 1/10 MHz (1 or 10 MHz) XTAL jumper selects the frequency of the square wave used as a clock by
the A/D pacer circuitry. This pacer circuitry controls the sample timing of the A/D. The output driving the
A/D converter is also available at the CTR 2 output pin on the main connector.
To maintain full compatibility with the original DAS-16, the CIO-DAS1400 required a 1 MHz crystal
oscillator. When MetraByte redesigned the DAS-16 and added the faster 10MHz crystal, a jumper was
provided to maintain compatibility with older software. The CIO-DAS1400 has the jumper because the
DAS-16 has the jumper. For older software, the jumper must be in the 1 MHz position. If you are not
concerned with compatibility with older software, use the 10MHz position.
The CIO-DAS1400 is shipped with the jumper in the 1 MHz position (see Figure 3-3). Figure 3-3 Clock Select Jumper
3.4 8/16 CHANNEL SELECT
The Analog inputs of the CIO-DAS1400 can be configured for eight differential or 16
single-ended inputs. Use the single-ended input mode if you have more than eight, low-noise
analog inputs to sample. Using the differential input mode allows up to 10 volts of common
mode noise rejection..
The CIO-DAS1400 comes from the factory configured for 16 single-ended inputs and the 8/16
switch is in the position shown in Figure 3-4. Set it for the type (or number) of inputs you
require. On the CIO-DAS1402/16, this switch is located under the metal shield. If you need
access to this switch, this shield may be removed by removing the two screws on the back of
the CIO-DAS1402/16. Figure 3-4. 8/16 Channel Select Switch
3.5 BIPOLAR/UNIPOLAR MODE SELECTION
The Bipolar or Unipolar configuration of the A/D converter is set by a switch. This switch is
shown in Figure 3-5.. The switch controls all A/D channels. Although you cannot mix bipolar
and unipolar channels, you can measure a unipolar input in the bipolar mode. (e.g., you can
monitor a 0 to 5V input with a ±5 V channel). On the CIO-DAS1402/16, this switch is located
under the metal shield. If you need access to this switch, this shield may be removed by
removing the two screws on the back of the CIO-DAS1402/16.
Figure 3-5. Bipolar/Unipolar Select Switch
Input amplifier gain is controlled by a software-programmed register located at BASE + B hex (11 decimal). Refer to the Register
Architecture section for details on this register.
-2-
CLK SEL
1
10
Default 1MHz Shown
16/8 CHANNEL SELECT SWITCH
16 Channel differential-input
mode shown
16 CHAN 8
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com

3.6 PACER EDGE SELECT
The original Keithley MetraByte DAS-1600 was designed such that A/D conversion was initiated on
the falling (trailing) edge of the convert signal from the internal pacer. Neither the original DAS-16,
nor any of the other DAS-16 derivations convert on the falling edge. We are not aware of any A/D
board that uses the falling edge to initiate the A/D conversion.
When using the falling edge to start the conversion, the A/D may be falsely triggered by 8254 pacer
clock initialization glitching (easy to avoid but a real possibility in the DAS-1600). Converting on the
falling edge mode also may lead to timing differences if the CIO-DAS1400 board is being used as a
replacement for an older DAS16 series board.
Because using the falling edge trigger is undesirable, the CIO-DAS1400 has a jumper which allows
you choose which edge of the internal pacer signal starts the A/D conversion. The jumper has no
effect on an external pacer signal (EXTCLOCK). The only reason we supply you the option of a
falling edge trigger is to provide complete compatibility for those who have developed software for a
DAS-1600 using the AS-1600 drivers, AND, when using the CIO-DAS1400 with that software you
observe sample timing differences. Figure 3-6. Pacer Edge Select
The CIO-DAS1400 is shipped with the jumper in the rising (leading) edge position. Figure 3-6 shows the edge selection options. For
compatibility with all third party packages, with all DAS-16 software and with CIO-DAS1400 software, leave this jumper in the rising
edge position.
3.7 AUXILIARY TRIGGER
There is a position for a header connector at the rear of the CIO-DAS1400. This connector provides the same function as that found on
the DAS-1600.
The A/D trigger signal may come from this connector, if installed. A jumper controls which pin the trigger signal comes in from. We
do not install this connector (nor is it installed on the DAS-1600).
3.8 BURST MODE GENERATOR
The burst mode generator is a clock signal that paces the A/D at the maximum multi-channel sample rate, then periodically performs
additional maximum-rate scans. In this way, the channel-to-channel skew (time between successive samples in a scan) are minimized
without taking a large number of undesired samples (see Figure 3-7).
Figure 3-7. Burst Mode Generator Timing
The CIO-DAS1400 burst mode generator takes advantage of the fast A/D. The burst mode skew is 4.0 ms between channels for the
CIO-DAS1400/12. It is 13.3 ms for the CIO-DAS1402/16.
-3-
TRIGGER EDGE SELECT
JUMPERBLOCK
J9
J9
Falling Edge A/D Trigger
DAS-1600 Method
Rising Edge A/D Trigger
DAS-16 Method
Default
Setting
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com

4 CONNECTOR PINOUTS
The CIO-DAS1400 analog connector is a 37-pin, “D”-connector accessible from the rear of the PC on the expansion back plate. The
signals available are identical to the DAS-16, or optionally, an additional signal, SS&H OUT (Simultaneous Sample & Hold), is
available at pin 26.
The connector accepts female 37D type connectors, such as on the C73FF-2, a two-foot cable. If frequent changes to signal
connections or signal conditioning is required, we strongly recommend purchasing the CIO-MINI37 screw terminal board and the
mating C37FF-2 cable.
Figure 4-1. CIO-DAS1400 Analog Signal Connector
-4-
LLGND 19
CH0 LOW / CH8 HIGH 18
CH1 LOW / CH9 HIGH 17
CH2 LOW / CH10 HIGH 16
CH3 LOW / CH11 HIGH 15
CH4 LOW / CH12 HIGH 14
CH5 LOW / CH13 HIGH 13
CH6 LOW / CH14 HIGH 12
CH7 LOW / CH15 HIGH 11
n/c 10
n/c 9
-5V REF OUT 8
DIG GND 7
DIG IN 1 6
DIG IN 3 5
DIG. OUT 1 4
DIG. OUT 3 3
CTR 0 OUT 2
+5V PC BUS 1
37 CH0 HIGH
36 CH1 HIGH
35 CH2 HIGH
34 CH3 HIGH
33 CH4 HIGH
32 CH5 HIGH
31 CH6 HIGH
30 CH7 HIGH
29 LLGND
28 LLGND
27 n/c
26 SS&H OUT
25 DIG IN 0 / TRIGGER
24 DIG IN 2 / CTR0 GATE
23 DIG OUT 0
22 DIG OUT 2
21 CTR 0 CLOCK IN
20 CTR 2 OUT
37 PIN CONNECTOR
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com

5 ANALOG CONNECTIONS
5.1 ANALOG INPUTS
Analog signal connection is one of the most challenging aspects of applying a data acquisition board. If you are an electrical engineer
you may wish to skip this section, but for many PC data acquisition users, the best way to connect your analog inputs may not be
obvious. While complete coverage of this topic is beyond the scope of this manual, the following section provides some explanations
and helpful hints regarding analog input connections. This section is included to help you achieve the optimum performance from your
CIO-DAS1400 series board.
Before making connections, you should have a basic understanding of Single-Ended/Differential inputs and signal grounding/isolation.
If you are already familiar with these topics, skip to the next section.
The CIO-DAS1400 provides either 8 differential or 16 single-ended input channels. Single-ended and differential inputs are described
in the following section.
5.1.1 Single-Ended Inputs
A single-ended input measures the voltage between the input signal and ground. In single-ended mode, the CIO-DAS1400 measures
the voltage between the input channel and LLGND. The single-ended input configuration requires only one physical connection (wire)
per channel and allows the CIO-DAS1400 to monitor more channels than the 2-wire differential configuration using the same
connector and onboard multiplexor. However, since the CIO-DAS1400 is measuring the input voltage relative to its own low level
ground, single-ended inputs are more susceptible to both EMI (electro-magnetic interference) and any ground noise at the signal
source. Figure 5-1 shows the single-ended input configuration
Figure 5-1. Single-Ended Input Configration
5.1.2 Differential Inputs
Differential inputs measure the voltage between two distinct input signals. Within a certain range (referred to as the common mode
range), the measurement is almost independent of signal source to CIO-DAS1400 ground variations. A differential input is also much
more immune to EMI than a single-ended one. Most EMI noise induced in one lead is also induced in the other, the input only
measures the difference between the two leads, and the EMI common to both is ignored. This effect is a major reason there is twisted
pair wire as the twisting assures that both wires are subject to virtually identical external influence. Figure 5-2 shows a typical
differential input configuration.
-5-
+
-
Input
Amp To A/D
LL GND
CH IN
~
12
Vs Vs + V
g
2 - V
g
1
An
y
volta
g
e differential between
g
rounds
g
1 and
g
2 shows up as an error si
g
nal
at the input amplifier
Sin
g
le-ended input with Common Mode Volta
g
e
g
g
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com

Figure 5-2. Differential Input - Common Mode Voltage Rejection
Before moving on to the discussion of grounding and isolation, it is important to explain the concepts of common mode, and common
mode range (CM Range). Common mode voltage is depicted in the diagram above as Vcm. Though differential inputs measure the
voltage between two signals, without (almost) respect to the either signal’s voltages relative to ground, there is a limit to how far away
from ground either signal can go. Though the CIO-DAS1400 has differential inputs, it will not measure the difference between 100V
and 101V as 1 Volt (in fact the 100V would destroy the circuit!). This limitation or common mode range is depicted graphically in
Figure 5-3. The CIO-DAS1400 common mode range is +/- 10 Volts. Even in differential mode, no input signal can be measured if it is
more than 10V from the board’s low level ground (LLGND).
Figure 5-3. Common Mode Voltage Range Values
-6-
+
-
Input
Amp To A/D
Differential
Input
LL GND
CH High
CH Low
~
Vs Vs
Vcm
Common Mode Voltage (Vcm) is ignored
by differential input configuration. However,
note that Vcm + Vs must remain within
the amplifier’s common mode range of ±10V
Vcm = Vg2 - Vg1 gg1 2
+
-
Input
Amp To A/D
Differential Input
I/O
Connector
LL GND
CH High
CH Low
+1V
-13V
+2V
-12V
+3V
-11V
+4V
-10V
+5V
-9V
+6V
-8V
+7V
-7V
+8V
-6V
+9V
-5V
+10V
-4V
+11V
-3V
+12V
-2V
+13V
-1V
Gray area represents common mode range
Both V+ and V- must always remain within
the common mode range relative to LL Gnd
Vcm (Common Mode Voltage) = +5 Volts
Vcm
With Vcm= +5VDC,
+Vs must be less than +5V, or the common mode range will be exceeded (>+10V)
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com

5.2 SYSTEM GROUNDS and ISOLATION
There are three possibilities when connecting a signal source to the CIO-DAS1400 board:
The CIO-DAS1400 and the signal source may have the same (or common) ground. This signal source can be connected directly to the
board.
The CIO-DAS1400 and the signal source may have an offset voltage between their grounds (AC and/or DC). This offset is commonly
referred to as a common mode voltage. Depending on the magnitude of this voltage, it may or may not be possible to connect the
board directly to your signal source. We will address this topic further in a later section.
The CIO-DAS1400 and the signal source may have isolated grounds. This signal source can be connected directly to the board.
5.2.1 Ground Testing
Perform the following test: Using a battery powered voltmeter*, measure the voltage between the ground signal at your signal source
and at your PC. Place one voltmeter probe on the PC ground and the other on the signal source ground. Measure both the AC and DC
Voltages.
*If you do not have access to a voltmeter, skip the test and read the following three sections. You may be able to identify your system
type from the descriptions provided.
If both AC and DC readings are 0.00 volts, you may have a system with common grounds. However, since voltmeters will average out
high frequency signals, there is no guarantee. Please refer to the section below titled Common Grounds.
If you measure reasonably stable AC and DC voltages, your system has an offset voltage between the grounds. This offset is referred to
as a Common Mode Voltage. Read and observe the following warning, then proceed to the section describing Common Mode systems.
WARNING
An offset voltage greater than 30 volts can cause injury or death. It may also only damage board and computer circuitry. Use extreme
care. If either the AC or DC voltage is greater than 10 volts, do not connect a CIO-DAS1400 series board to this signal source. You are
beyond the board’s usable common mode range and will need to either adjust your grounding system or add special signal isolation
conditioning in order to take useful measurements.
If you cannot obtain a reasonably stable DC voltage measurement between the grounds, or the voltage drifts considerably, the two
grounds are most likely isolated. To check for isolation, change your voltmeter to a resistance scale and measure the resistance
between the two grounds. Turn both systems OFF prior to taking this resistance measurement. If the measured resistance is more than
100 Kohm, it’s a fairly safe bet that your system has electrically isolated grounds.
5.2.2 Systems with Common Grounds
In the simplest (but perhaps least likely) case, your signal source will have the same ground as the CIO-DAS1400. This would
typically occur when providing power or excitation to your signal source directly from the board. There may be other common ground
configurations, but it is important to note that any voltage between the CIO-DAS1400 ground and your signal ground is a potential
error voltage if you set up your system based on a common ground assumption.
As a safe rule of thumb, if your signal source or sensor is not connected directly to an LLGND pin on your board, it’s best to assume
that you do not have a common ground even if your voltmeter measured 0.0 Volts. Configure your system as if there is ground offset
voltage between the source and the CIO-DAS1400. This is especially true if you are using either the CIO-DAS1402/16 or the
CIO-DAS1402/12 at high gains, since ground potentials in the sub-millivolt range will be large enough to cause A/D errors, yet will
not likely be measured by your handheld voltmeter.
5.2.3 Systems with Common Mode (Ground-Offset) Voltages
The most frequently encountered grounding scenario involves grounds that are loosely connected, but have AC and/or DC offset
voltages between the board and the signal source ground. This offset voltage may be AC, DC, or both and may be caused by a number
of things including EMI pickup or resistive voltage drops in ground wiring and connections.
5.2.4 Small Common Mode Voltages
If the voltage between the signal source ground and board ground is small, the combination of the ground voltage and input signal will
not exceed the CIO-DAS1400’s +/-10V common mode range, (i.e. the voltage between grounds, added to the maximum input voltage,
-7-
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com

stays within +/-10V), This input is compatible with the CIO-DAS1400 and the system may be connected without additional signal
conditioning. Fortunately, most systems fall in this category and have a small voltage differential between grounds.
5.2.5 Large Common Mode Voltages
If the ground differential is large enough, the board’s +/- 10V common mode range will be exceeded (i.e. the voltage between
CIO-DAS1400 and signal source grounds, added to the maximum input voltage you’re trying to measure exceeds +/-10V). In this case
the CIO-DAS1400 cannot be directly connected to the signal source. You must change your system grounding configuration or add
isolation signal conditioning. (Please look at our ISO-RACK and ISO-5B-series products to add electrical isolation, or give our
technical support group a call to discuss other options).
CAUTION
Do not rely on the earth prong of a 120VAC for signal ground connections. Different ground plugs may have large and potentially
even dangerous voltage differentials. Remember that the ground pins on 120VAC outlets on different sides of the room may only be
connected in the basement. This leaves the possibility that the “ground” pins may have a significant voltage differential (especially if
the two 120 VAC outlets happen to be on different phases!)
5.2.6 Isolated Grounds Exist
Some signal sources may be electrically isolated from the CIO-DAS1400. Figure 5-4 shows a typical isolated ground system. These
signal sources are often battery powered. Isolated ground systems provide excellent performance, but require some extra care during
connections to assure optimum performance is obtained. Please refer to the following sections for further details.
5.3 WIRING CONFIGURATIONS
Combining all the grounding and input type possibilities provides us with the following potential connection configurations. The
combinations along with our recommendations on usage are shown in Table 5-1 below.
Table 5-1. Recommended Input Configurations
RecommendedDifferential Inputs
Already Isolated
Grounds
AcceptableSingle-ended InputsAlready Isolated Grounds
Unacceptable without
adding Isolation
Differential Inputs
Common Mode
Voltage > +/-10V
Unacceptable without
adding Isolation
Single-Ended Inputs
Common Mode
Voltage > +/- 10V
RecommendedDifferential Inputs
Common Mode
Voltage < +/-10V
Not RecommendedSingle-Ended Inputs
Common Mode
Voltage < +/-10V
AcceptableDifferential InputsCommon Ground
RecommendedSingle-Ended InputsCommon Ground
OUR VIEWINPUT CONFIGURATIONGROUND CATEGORY
The following sections show recommended input wiring schemes for each of the eight possible input configuration/grounding
combinations.
5.3.1 Common Ground / Single-Ended Inputs
Single-ended is the recommended configuration for common ground connections. However, if some of your inputs are common ground
and some are not, we recommend you use the differential mode. There is no performance penalty (other than loss of channels) for
-8-
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com

using a differential input to measure a common ground signal source. However the reverse is not true. Figure 5-4 is a connection
diagram for a common ground / single-ended input system.
Figure 5-4. Single-Ended, Common Ground
5.3.2 Common Ground / Differential Inputs
The use of differential inputs to monitor a signal source with a common ground is a acceptable configuration though it requires more
wiring and offers fewer channels than selecting a single-ended configuration. Figure 5-5 shows the recommended connections in this
configuration.
Figure 5-5. Differential Input, Sharing Common Ground
5.3.3 Common Mode Voltage Less Than +/-10V / Single-Ended Inputs
This is not a recommended configuration. In fact, the phrase common mode has no meaning in a single-ended system and this case
would be better described as a system with offset grounds. Anyway, you are welcome to try this configuration, no system damage
should occur and depending on the overall accuracy you require, you may receive acceptable results.
5.3.4 Common Mode Voltage, Less than +/-10V / Differential Inputs
Systems with varying ground potentials should always be monitored in the differential mode. Care is required to assure that the sum of
the input signal and the ground differential (referred to as the common mode voltage) does not exceed the common mode range of the
A/D board (+/-10V on the CIO-DAS1400). Figure 5-6 shows recommended connections in this configuration
-9-
+
-
Input
Amp To A/D
A/D Board
I/O
Connector
LL GND
CH IN


Signal
Source with
Common Gnd
Optional wire
since signal source
and A/D board share
common ground
Si
g
nal source and A/D board
sharin
g
common
g
round connected
to sin
g
le-ended input.
+
-
Input
Amp To A/D
A/D Board
I/O
Connector
LL GND
CH High
CH Low


Signal
Source with
Common Gnd
Optional wire
since signal source
and A/D board share
common ground
Required connection
of LL GND to CH Low
Signal source and A/D board
sharing common ground connected
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com

.
Figure 5-6. Differential Input, Maximum Common Mode Voltage Requirement
5.3.5 Common Mode Voltage, Greater Than +/-10V
The CIO-DAS1400 will not directly monitor signals with common mode voltages greater than +/-10V. You will either need to alter the
system ground configuration to reduce the overall common mode voltage, or add isolated signal conditioning between the source and
your board . See Figures 5-7 and 5-8.
Figure 5-7. Common Mode Voltage Greater Than +/-10V, Differential Input
.
Figure 5-8. Common Mode Voltage Greater Than +/-10V, Single-Ended Input w/Isolation Barrier
-10-
+
-
Input
Amp To A/D
A/D Board
I/O
Connector
LL GND
CH High
CH Low


Signal Source
with Common
Mode Voltage
Signal source and A/D board
with common mode voltage
connected to a differential input.
GND
The volta
g
e differential
between these
g
rounds,
added to the maximum
input si
g
nal must stay
within +/-10V
System with a Large Common Mode Voltage,
Connected to a Differential Input


L
arge common
mode voltage
between signal
source & A/D board
GND
I
so
l
at
i
on
Barrier
When the voltage difference
between signal source and
A/D board ground is large
enough so the A/D board’s
common mode range is
exceeded, isolated signal
conditioning must be added.
+
-
Input
Amp To A/D
A/D Board
I/O
Connector
LL GND
CH High
CH Low
10 K
10K is a recommended value. You may short LL GND to CH Low
instead, but this will reduce your system’s noise immunity.
System with a Large Common Mode Voltage,
Connected to a Single-Ended Input
I/O
Connector
+
-
Input
Amp To A/D
LL GND
CH IN
A/D Board


L
arge common
mode voltage
between signal
source & A/D board
GND
Isolation
Barrier
When the voltage difference
between signal source and
A/D board ground is large
enough so the A/D board’s
common mode range is
exceeded, isolated signal
conditioning must be added.
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com

5.3.6 Isolated Grounds / Single-Ended Inputs
Single-ended inputs can be used to monitor isolated inputs, though the use of the differential mode will increase you system’s noise
immunity. The diagram below shows the recommended connections is this configuration.
Figure 5-9. Isolated Ground - Single-Ended input
5.3.7 Isolated Grounds / Differential Inputs
Optimum performance with isolated signal sources is assured with the use of the differential input setting. The diagram below shows
the recommend connections is this configuration.
Figure 5-10. Isolated Grounds - Differential Input
-11-
Isolated Si
g
nal Source
Connected to a Sin
g
le-Ended Input
I/O
Connector
+
-
Input
Amp To A/D
LL GND
CH IN
A/D Board


Isolated
signal
source
+
-
Input
Amp To A/D
A/D Board
I/O
Connector
LL GND
CH High
CH Low


Signal Source
and A/D Board
Already Isolated.
Already isolated signal source
and A/D board connected to
a differential input.
GND
These grounds are
electrically isolated.
10 K
10K is a recommended value.You may short LL GND to CH Low
instead, but this will reduce your system’s noise immunity.
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com

6 REGISTER ARCHITECTURE
6.1 INTRODUCTION
There are three ways to generate software for CIO-DAS1400 series boards. These are:
Writing custom software using our Universal Library package.
Using a fully integrated software package (e.g. SoftWire).
Doing direct register-level programming.
CUSTOM SOFTWARE UTILIZING THE UNIVERSAL LIBRARY
Most customers write custom software using Measurement Computing’s Universal Library. The Universal Library takes care of all the
board I/O commands and lets you concentrate on the application part of the software. For additional information regarding using the
Universal Library, please refer to the documentation supplied with the Universal Library
FULLY INTEGRATED SOFTWARE PACKAGES (e.g. SoftWire)
Many customers also take advantage of the power and simplicity offered by one of the high-level data acquisition packages. Please
refer to the package’s documentation for setup and usage details.
DIRECT REGISTER-LEVEL PROGRAMMING
Though uncommon, some applications may not allow the use of our Universal Library and a high-level package may not be available.
For this case, a detailed register mapping for experienced programmers follows.
6.2 CONTROL & DATA REGISTERS
The CIO-DAS1400 is controlled and monitored by reading and writing 24 I/O addresses. The first address is referred to as the BASE
ADDRESS (BADR) and is set by a bank of switches on the board. All other addresses are located at the BASE ADDRESS plus a
specified offset. In particular, the main analog I/O functions are controlled by the I/O addressees from BADR to BADR +F hex and
BADR +404 hex through BADR +407 hex. Although registers are easy to read and write to, unless there is a specific reason to write
your program at the register lever, we highly recommend you use our Universal Library.
The method of programming required to set/read bits from bytes is beyond the scope of this manual. The remainder of this chapter is
included for those experienced programmers who wish to write their own registe level programs.
-12-
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com

The registers and their functions are listed in Table 6-1. Each register has eight bits for either a byte of data or individual bit functions.
Table 6-1. Register Addresses and Functions
NoneStatus of extended featuresBASE + 407h DAS 1400 Enable/DisableNoneBASE + 406h Burst Mode Enable/DisableNoneBASE + 405h Conversion Enable/DisableNoneBASE + 404h NoneNoneBASE + 403h NoneNoneBASE + 402h NoneNoneBASE + 401h NoneNoneBASE + 400h Pacer Clock Control (8254)None. No read back on 8254BASE + Fh CTR 2 Data - A/D PacerCTR 2 Data - A/D Pacer ClockBASE + Eh CTR 1 Data - A/D PacerCTR 1 Data - A/D Pacer ClockBASE + Dh Counter 0 DataCounter 0 DataBASE + Ch PGA Control/DT resetPGA gainBASE + Bh Burst Length/pacer clk cntrlnoneBASE + Ah Set DMA, INT etcDMA, Interrupt & Trigger ControlBASE + 9 Clear InterruptStatus EOC, UNI/BIP etc.BASE + 8 NoneNoneBASE + 7 NoneNoneBASE + 6 NoneNoneBASE + 5 NoneNoneBASE + 4 Digital 4-Bit OutputDigital 4-Bit InputBASE + 3 Channel MUX / FIFO resetChannel MUXBASE + 2 NoneA/D Data (Most significant byte)BASE + 1 Start A/D ConversionA/D Data (Least significant four bits)BASE WRITE FUNCTIONREAD FUNCTIONADDRESS
6.2.1 A/D Data & Channel Registers (CIO-DAS140#/12
Base Address +0
CH0CH1CH2CH3A/D 0
LSB
A/D 1A/D 2A/D 3 01234567
This register is read/write.
READ
On read, it contains two types of data. The least significant four digits of the analog input data and the channel number from which the
current data was taken.
These four bits of analog input data must be combined with the eight bits of analog input data in BASE + 1, forming a complete 12-bit
number. The data is in the format 0 = minus full scale. 4095 = +FS.
The channel number is binary. If the current channel were five, then bits CH2 and CH0 would be high, CH3 and CH1 would be low.
WRITE
Writing any data to the register causes an immediate A/D conversion.
BASE ADDRESS +1
A/D 4A/D 5A/D 6A/D 7A/D 8A/D 9A/D 10A/D 11 01234567
MSB
This register is read-only.
On read, the most significant A/D byte is read.
-13-
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com

6.2.2 A/D Data & Channel Registers (CIO-DAS1402/16)
BASE ADDRESS
A/D 0
LSB
A/D 1A/D 2A/D 3A/D 4A/D 5A/D 6A/D 7 01234567
This register is read/write.
READ
On read, it contains the least significant eight digits of the analog input data.
These eight bits of analog input data are combined with the eight bits of analog input data in BASE + 1, forming a complete 16-bit
number. The data is in the format 0 = minus full scale. 65,535 = +FS.
WRITE
Writing any data to the register causes an immediate A/D conversion.
BASE ADDRESS +1
A/D 8A/D 9A/D 10A/D 11A/D 12A/D 13A/D 14A/D 15
MSB
01234567
This register is read-only. On read, the most significant A/D byte is read.
6.2.3 Channel MUX Scan Limits Register
BASE ADDRESS +2
CH L0CH L1CH L2CH L3CH H0CH H1CH H2CH H3 01234567
This register is read and write.
READ
The current channel scan limits are read as one byte. The high channel number scan limit is in the most significant four bits. The low
channel scan limit is in the least significant four bits.
WRITE
The channel scan limits desired are written as one byte. The high channel number scan limit is in the most significant four bits. The
low channel scan limit is in the least significant four bits.
NOTE
Every write to this register sets the current A/D channel MUX setting to the number in bits 0-3 and resets the FIFO. See BASE + 8.
6.2.4 Four-Bit Digital I/O Registers
BASE ADDRESS +3 (when read)
DI0, TRIGDI1DI2, CTR0 GATEDI30011 01234567
READ
The signals present at the inputs are read as one byte, the most significant four bits of which are always zero. Pins 25 (digital input 0)
and 24 (digital input 2) digital inputs have two functions each.
The TRIG function of digital input 0 may be used to hold off the first sample of an A/D set by holding it low (0V) until you are ready
to take samples, which are then paced by the 8254. It can also be used as the source of an external start conversion pulse,
synchronizing A/D conversions to some external event.
-14-
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com

BASE ADDRESS +3 (when written to)
DO0DO1DO2DO3XXXX 01234567
WRITE
The upper four bits are ignored. The lower four bits are latched TTL outputs. Once written, the state of the inputs cannot be read back
because a read back would read the separate digital input lines (see above).
NOTE
Since the digital inputs have multiple functions, use the digital input lines 0-3 with care when you are also using the A/D converter.
The digital outputs are also used by the CIO-EXP32, 32-channel analog multiplexer/amplifier.
6.2.5 Status Registers
BASE ADDRESS + 8
CH0CH1CH2CH3INTMUXU/BEOC 01234567
This register is read-mostly, one-function-write.
READ
EOC = 1, the A/D converter is busy. EOC = 0, it is free.
U/B = 1, the amplifier is in Unipolar mode. U/B = 0, is bipolar.
MUX = 1, Channels are configured 16, single-ended. MUX = 0, 8 differential.
INT = 1, an interrupt has been received. INT = 0, ready to receive an interrupt. An interrupt service routine must clear
this bit after each interrupt.
CH3, CH2, CH1 & CH0 are bits in a binary number between 0 and 15 indicating the MUX channel currently selected. It is valid only
when EOC = 0. The channel MUX increments shortly after EOC = 1 so may be in a state of transition when EOC = 1.
WRITE
A write of any data to this register sets the INT bit to 0.
6.2.6 DMA, Interrupt & Trigger Control
BASE ADDRESS + 9
TS0TS1DMAXIR0IR1IR2INTE 01234567
This register is read and write.
READ
INTE = 1, interrupts are enabled. An interrupt generated will be placed on the PC bus interrupt level selected by IR4, IR2, and IR1.
INTE = 0, interrupts are disabled.
IR2, IR1, IR0 are bits in a binary number between 0 and 7 which map interrupts onto the PC bus interrupt levels 2 - 7. Interrupts 0 and
1 can not be asserted by the CIO-DAS1400.
-15-
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com