CIO-DO24DD&
CIO-DO48DD
User’s Manual

Revision 5A
November, 2000

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NoticeMeasurement Computing Corporation does not authorize any Measurement Computing Corporation product for
use in life support systems and/or devices without prior written consent from Measurement Computing
Corporation. Life support devices/systems are devices or systems that, 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 ininjury. Measurement Computing Corporation products are not designed with the components required, and are
not subject to the testing required to ensure a level of reliability suitable for the treatment and diagnosis ofpeople.

(C) Copyright 2000 Measurement Computing Corporation
HM CIO-DO##DD.lwp

TABLE OF CONTENTS
1.0 INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1 DIRECT DRIVE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 DARLINGTON TRANSISTORS . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.3 CLAMPING VOLTAGE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
2.0 SOFTWARE INSTALLATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
3.0 HARDWARE INSTALLATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
3.1 BASE ADDRESS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
3.2 INSTALLING IN THE COMPUTER . . . . . . . . . . . . . . . . . . . . . . . 4
4.0 INTERFACING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4.1 CONNECTOR DIAGRAMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4.2 CABLING TO THE CONNECTOR . . . . . . . . . . . . . . . . . . . . . . . . 6
4.3 CONNECTOR PIN ASSIGNMENTS . . . . . . . . . . . . . . . . . . . . . . . 6
4.4 THE OUTPUT CIRCUIT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
4.5 SIGNAL CONNECTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
4.6 CLAMPING VOLTAGE INPUT . . . . . . . . . . . . . . . . . . . . . . . . . . 8
4.7 TEST CONNECTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
5.0 CONTROL & DATA REGISTERS . . . . . . . . . . . . . . . . . . . . . . . . . 10
5.1 INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
5.2 REGISTER FORMATS - BOTH 24- AND 48-BIT VERSIONS . . . . . 11
5.3 REGISTER FORMAT-CIO-DO48DD, CONNECTOR P2 ONLY . . . . 11
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
6.0 SPECIFICATIONSThis page is blank.

1.0 INTRODUCTION
CIO-DO24DD and CIO-DD48DD are desig ned for switching circuits of higher
voltage and current than standard TTL type components are capable of. They provide
24 and 48 outputs respectively.
The ‘DD’ designation indicates that these boards are capable of ‘Direct Drive.’ The
current specification that earns the direct drive designation is a switching capacity of
up to 500 mA.
Throughout this manual the part number CIO-DO24DD is used for both products
since most of information applies to both. W here necessary, the appropriate partnumber is noted.
Both the CIO-DO24DD and the CIO-DD48DD are s upported by the Universal
Library programming library for DOS and Windows available from Measurement
Computing.

1.1 DIRECT DRIVE
The CIO-DO24DD is similar to a set of non-isolated solid state relays. The digital
lines of the DD are capable of completing a circuit to ground thereby allowing current
to flow in the circuit. Because there is a small amount of OFF current flowing in thecircuit, like a solid state relay, the circuits on a DD board are not ideal for switching
low level signals. If you have a circuit that is suitable for solid state relays and does
not need isolation, the DD board can be substituted.

1.2 DARLINGTON TRANSISTORS
Each output is an NPN Darlington pair. All outputs are open collector and incorporate
clamping diodes for transient suppression. The ability to withstand transients, connect
directly to voltages up to 50V and sink as much as 500 mA make these outputs ideallysuited for controlling lamps, relays, printer hammers and similar loads.

1.3 CLAMPING VOLTAGE
The clamping voltage is th at voltage which, when exceeded, is clam ped to prev ent
damage to th e circuit. The clamping voltage of each 8-bit port can be set
independently and must be supplied externally. In addition, the open collector pointsof each 8-bit port can be pulled to a common voltage by connecting an eight-resistor
SIP.
12.0 SOFTWARE INSTALLATIONOn the disk labeled InstaCal there is an installation program. Please run this programand accept the defaults. Refer to th e Extended Software Installation Manual forcomplete instructions. If you have purchased the Universal L ibrary for programming
language support, use that disk to install both InstaCal and the Universal Library.
InstaCal will guide you through switch and jumper settings you may need to makebefore installing y our board. Detailed information on hardware settings is also
provided below.

3.0 HARDWARE INSTALLATION

3.1 BASE ADDRESSThe boards are setup at the factory with the base address set to 300h (768 decimal). If
there are no other devices installed in your computer that are using addresses 300h
through 304h (or 308h if using the CIO-DO48DD), do not change the base address.
The CIO-DO24DD employs the PC bus for power, communications and data transfer.
As such it draws power from the PC, monitors the address lines and control signals
and responds to it’s I/O address, and places data on the eight data lines.
The BASE address is the only user selectable bu s related feature of the
CIO-DO24DD. The base address identifies the registers that software writes to whencommunicating with the CIO-DO24DD.
A block of eight (or seven) DIP switches are used for setting the base address. Eachswitch position corresponds to one of the PC bus address lines. Placing a switch down
asserts that address bit.
A complete address is constructed by calculating the HEX or decimal number whichcorresponds to all the address bits the board has been instructed to respond to. For
example, in Figure 3-1, (for CIO-DO24DD) address switches 9 and 8 for are DOWN,
all others UP. See Fig ure 3-2 for the address select switches for the CIO-DO48DD.
Address 9 = 200h (512D) and address 8 = 100h (256 decimal), when added together
they equal 300h (768 decimal).

2

Figure 3-1. CIO-DO24DD Address Select Switches
NOTE
DISREGARD THE NUMBERS PRINTED ON T HE SWITCH.
REFER TO THE NUMBERS PRINTED IN W HITE ON T HE
BOARD!

9

8

7

6

5

4

3

SW
A9
A8
A7
A6
A5
A4
A3

HEX
200
100
80
40
20
10
08

B A SE A D D R ESS SW ITC H - A d d re ss 3 0 0 H sh o w n h e reFigure 3-2. CIO-DO48DD Address Select Switches
Certain addresses are u sed by the PC, others are free and can be u sed by the
CIO-DO24DD and other expansion boards. R efer to Table 3-1 for PC register
addressing. We recommend BASE = 300h (768 decimal) be tried first.

3

HEX
RANGE
000-00F
020-021040-043060-063060-064070-071080-08F
0A0-0A1
0A0-0AF
0C0-0DF
0F0-0FF
1F0-1FF
200-20F
210-21F
238-23B
23C-23F
270-27F
2B0-2BF

Table 3-1. PC I/O Addresses
FUNCTION
HEX
RANGE
8237 DMA #1
2C0-2CF8259 PIC #1
2D0-2DF
8253 TIMER
2E0-2E78255 PPI (XT)
2E8-2EF
8742 CONTROLLER (AT)
2F8-2FFCMOS RAM & NMI MASK (AT)
300-30FDMA PAGE REGISTERS
310-31F
8259 PIC #2 (AT)320-32FNMI MASK (XT)378-37F
8237 #2 (AT)380-38F
80287 NUMERIC CO-P (AT)3A0-3AF
HARD DISK (AT)
3B0-3BBGAME CONTROL
3BC-3BF
EXPANSION UNIT (XT)
3C0-3CFBUS MOUSE
3D0-3DFALT BUS MOUSE
3E8-3EFPARALLEL PRINTER
3F0-3F7EGA
3F8-3FFFUNCTION
EGA
EGA
GPIB (AT)SERIAL PORTSERIAL PORTPROTOTYPE CARD
PROTOTTYPE CARD
HARD DISK (XT)
PARALLEL PRINTER
SDLC
SDLC
MDA
PARALLEL PRINTEREGACGASERIAL PORTFLOPPY DISKSERIAL PORTThe CIO-DO24DD BASE switch can be set for address in the range of 000-3FC so it
should not be hard to find a free address area for CIO-DO24DD. Once again, if you
are not using IBM prototyping cards or s ome other board which occupies theseaddresses, then 300-31F HEX are free to use.
Addresses not specifically listed, such as 390-39F, are not reserved and may beavailable. Check your computer for other boards which may use I/O addresses.

3.2 INSTALLING IN THE COMPUTER
1. Turn the power off.
2. Remove the cover of your computer. Please be careful not to dislodge any of thecables installed on the boards in your computer as you slide the cover off.
3. Locate an empty expansion slot in your computer.
4. Push the board firmly down into the exp ansion bus connector. If it is not seatedfully it may fail to work and could short circuit the P C bus power onto a PC bus
signal. This could damage the m otherboard in your PC as well as the
CIO-DO24DD.
4

4.0 INTERFACING

4.1 CONNECTOR DIAGRAMSThe output connector(s) is a 50-pin header type connector accessible from the rear of
the PC through the expansion back plate (Figure 4-1). The output signals are directconnections to the Darlington output transistor.
P1

P2

1A0
1A1
1A2
1A3
1A4
1A5
1A6
1A7
1B0
1B1
1B2
1B3
1B4
1B5
1B6
1B7
1C0
1C1
1C2
1C3
1C4
1C5
1C6
1C7

4

5

6

CIO-DO24DD PIN OUT or
CIO-DO48DD, P1 CONNECTOR

2A0
2A1
2A2
2A3
2A4
2A5
2A6
2A7
2B0
2B1
2B2
2B3
2B4
2B5
2B6
2B7
2C0
2C1
2C2
2C3
2C4
2C5
2C6
2C7

CIO-DO48DD, P2 CONNECTOR

Figure 4-1. Connector Pin Outs
The connectors accepts female 50-pin header type connectors, such as th ose on the
C50FF-2, a 2-foot cable with female connectors.
If frequent changes to signal co nnections or signal co nditioning is required, pleaserefer to the information on the CIO-TERM100, CIO-SPADE50 and CIO-MINI50
screw terminal boards.
5

4.2 CABLING TO THE CONNECTOR
The CIO-DO24DD connector is accessible through the PC/AT expansion bracket.
The connector is a standard 50-pin header connector. A cable with mating connectors(C50FF-##) can be purchased from Measurement Computing Corp. The second
output connector for the CIO-DO48DD is on the end of the card opposite theexpansion bracket.

4.3 CONNECTOR PIN ASSIGNMENTS
The connector is arranged so that there is generally a ground return for each control
line, and each 8 lines of a port are together on the cable.
The signal P ull Up# is the inp ut to the pull-up resistor SIP associated with a p ort.
Applying a voltage to that pin will pull up all lines of a port to that voltage through theuser-installed SIP resistor when the circuit is open.
The signal Port n Clamp is the clam ping voltage input for that port. For example, if
the circuit you are switching at port A is a 24 volt circuit but is subject to 100V
spikes, connect 24V to the Port A Clamp input and any signal over 24V will beclamped to 24V.

4.4 THE OUTPUT CIRCUITThe heart of the CIO-DO24DD is a Darlington pair of transistors. It is composed of a
ULN2803 and a few passive components. It works much the same as a solid state
relay. A simplified schematic of the circuit is shown in figure 4-2.
The load device is wired to the Output Pin so that your device is energized ON when apath to ground is completed. If desired, a clamping voltage can b e supplied to thePort N Clamp input.
The circuit is switched by the PC setting a register bit. When a 1 is written to a bit in
the register for a particular port, the Darlington transistors associated with that bit are
turned on and your circuit is completed via a path from the output pin to PC Ground.

6Figure 4-2. Darlington Output Circuit
All outputs share a com mon ground on the board so all your circuits must use thecommon ground. Also, as with any transistor circuit, there is a small amount of OFF
current.

4.5 PULL-UP RESISTORS
There are locations for pull-up resistors on the board. They are marked RN1 through
RN3 (through RN6 on the CIO-DO48DD).
These locations are designed to accept 9 pin SIP resistors configured as eig ht
individual resistors with one end in common. Each resistor in the SIP package makes
a connection between one of the Darlington collectors and the pin labeled “Pull Up #”for the port associated with that particular Darlington transistor.
For example, installing a 9 pin SIP resistor into the location marked “RN1” places a
resistor between all of the Darlington collectors for Port A1 and the pin labeled “Pull
Up 1”. A voltage applied to this pin becomes the supply voltage for all eight of the
Darlington transistors in Port A1.

4.6 SIGNAL CONNECTION
The output circuits are capable of completing a circuit of up to 50 volts and having acurrent of up to 500 mA.
1.

The voltage specification applies only when the transistor is off.
transistor can block up to 50V.
7

The

2.

The current specification applies on ly when the transistor is on. The
transistor can pass up to 500 mA.

Figure 4-3 is an example of a simple circuit. It shows a lamp with a 9 volt battery.
The positive battery terminal is connected to a co ntact of the lamp. The other lamp
connection is tied to the Darlington output. The negative side of the battery isconnected to GND (pin 44). When you write a 1 to the A0 bit, the Darlington turns oncompleting the circuit and the lamp lights.

Figure 4-3. Darlington Explained
Notice in Figure 4-3 above, that an equivalent, simplified circuit based on a resistor isshown to the right o f the Darlington circuit. The Darlington transistors act like aswitch which alternates between two resistors, one of great resistance and one ofminimal resistance. Notice that when the Darlington is OFF, th ere is some leakage
current flowing. Notice also that when the transistors are ON, there is a small voltage
drop across the Darlington. Both these aspects of the switch should be considered in
the design of your overall circuit.
The current can only flow from the pins labeled A#, B#, and C# to ground, and the PC
must share a common ground with your circuit.
For specifications of the leakage current and ON voltage of the Darlington, please see
the specifications in the back of this manual.

84.7 CLAMPING VOLTAGE INPUTThe output transistors can be set to clamp voltage spikes and prevent them fromdamaging your circuit. For example, if you are switching a 9V circuit, connect the
9V to the clamp input as well. This will hold transient voltages to less than 11V (9V+ 2V max forward voltage across the clamping diode at 350mA).

4.8 TEST CONNECTIONSThe CIO-DO24DD is a digital switching device. To test the installation and the board
you will need a kno wn working circuit to switch, such as a lamp bulb and battery
described previously.
After you have the circuit connected, the TEST option of the InstaCal program can beused to produce an alternating on/off signal at the switch.

95.0 CONTROL & DATA REGISTERS

5.1 INTRODUCTION
CIO-DO24DD is a direct drive, 24-line digital switching board built up of logic chips.
There are n o configuration registers as su ch. There are on ly four (or eight) buffer
registers for holding the output values. The output circuits are capable of switching up
to 500 mA at up to 50V.
Each board is composed of parallel ou tput chips. Each address contains one latch
and one buffer controlling 8 output pins. The ports are arranged in sets of 3, with anintervening unused address.
This scheme allows partial compatibility withapplications written to control 82C55 based boards in w hich the 8 2C55 is used for
output only. On those boards every fourth address contains a configuration register.
The partial compatibility arises from the lack o f a read back of the output buffers on
the CIO-DO24DD or CIO-DO48DD.
To write control data to an o utput register, the individual bits must be set to 0 or 1
then combined to form a byte.
Table 5-1 has the register assignments for the CIO-DO24DD and CIO-DO48DD.
Note that the last four registers (Base + 4 to +7) apply only to the CIO-DO48DD.

ADDRESS
BASE + 0
BASE + 1
BASE + 2
BASE + 3
BASE + 4
BASE + 5
BASE + 6
BASE + 7

Table 5-1. Register Assignments
READ FUNCTIONWRITE FUNCTION
ID CodePort 1A Outputs (24 & 48 bit models)NonePort 1B Outputs (24 & 48 bit models)NonePort 1C Outputs (24 & 48 bit models)
None
None
None
Port 2A Outputs ( 48 bit model only)
None
Port 2B Outputs ( 48 bit model only)
None
Port 2C Outputs ( 48 bit model only)
None
None

Notice that the register layout is very similar to that of a standard 82C55 based digital
I/O board and the other high drive digital output boards. The alignment of ports A, B
& C are id entical and the position normally occupied by the configuration register isleft empty. This is so your existing digital board software will work without
modification.

10

5.2 REGISTER FORMATS - BOTH 24- AND 48-BIT VERSIONSPORT 1A DATABASE ADDRESS + 0
7
6
1A7
1A6

5
1A5

4
1A4

3
1A3

2
1A2

1
1A1

0
1A0

PORT 1B DATABASE ADDRESS + 1
7
6
1B7
1B6

5
1B5

4
1B4

3
1B3

2
1B2

1
1B1

0
1B0

PORT 1C DATABASE ADDRESS + 2
7
6
1C7
1C6

5
1C5

4
1C4

3
1C3

2
1C2

1
1C1

0
1C0

5.3 REGISTER FORMAT-CIO-DO48DD, CONNECTOR P2 ONLYPORT 2A DATABASE ADDRESS + 4
7
6
2A7
2A6

5
2A5

4
2A4

3
2A3

2
2A2

1
2A1

0
2A0

PORT 2B DATABASE ADDRESS + 5
7
6
2B7
2B6

5
2B5

4
2B4

3
2B3

2
2B2

1
2B1

0
2B0

PORT 2C DATABASE ADDRESS + 6
7
6
2C7
2C6

5
2C5

4
2C4

3
2C3

2
2C2

1
2C1

0
2C0

11

6.0 SPECIFICATIONSPower consumption+5V
CIO-DO24DD
CIO-DO48DD

275mA typical, 345mA max
425mA typical, 535mA max

Digital Output
Digital TypeULN2803 Darlington (opencollector)

Configuration
CIO-DO24DD
CIO-DO48DD
Number of channels
CIO-DO24DD
CIO-DO48DD
Maximum output voltage, VCE
Maximum continuous current, Ic
Output leakage current
Vo = 50V, Ta = +70 °C
Vo = 50V, Ta = +25 °C
Collector-Emitter saturation voltage
iC= 350mA, iB = 500µA
iC= 200mA, iB = 350µA
iC= 100mA, iB = 250µA
Clamp diode reverse leakage current
Vr = 50V, Ta = +25 °C
Clamp diode forward voltage
Diode current = 350mA

3 banks of 8 outputs each
6 banks of 8 outputs each
24
48
50V
500mA
100 µA max
50 µA max
1.1V typ, 1.6Vmax
0.95V typ, 1.3Vmax
0.85V typ, 1.1Vmax
50 µA max
1.5V typ, 2.0V max

Environmental
Operating temperature range
Storage temperature range
Humidity

0 to 50°C−20 to 70°C
0 to 90% non-condensing

12For your notes.

13

For your notes.

14

EC Declaration of Conformity
We, Measurement Computing Corporation, declare under sole responsibility that the
product:
CIO-DO24DD &CIO-DO48DDPart Number

CURRENT OUTPUT BOARD
Description

to which this declaration relates, meets the essential requirements, is in conformity
with, and CE marking has been applied according to the relevant EC Directives listed
below using the relevant section of the following EC standards and other normative
documents:
EU EMC Directive 89/336/EEC: Essential requirements relating to electromagnetic
compatibility.
EU 55022 Class B: Limits and methods of measurements of radio interference
characteristics of information technology equipment.
EN 50082-1: EC generic immunity requirements.
IEC 801-2: Electrostatic discharge requirements for industrial process measurement
and control equipment.
IEC 801-3: Radiated electromagnetic field requirements for industrial process
measurements and control equipment.
IEC 801-4: Electrically fast transients for industrial process measurement and control
equipment.
Carl Haapaoja, Director of Quality Assurance

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