Measurement PC104-PDISO8 User Manual

PC104-DI48

User’s Manual

Revision 3

September, 2000

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b) support or sustain life and whose failure to perform can be reasonably expected to result in injury. Measurement
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required to ensure a level of reliability suitable for the treatment and diagnosis of people.

HM PC104-DI48.lwp

for more information about Measurement Computing trademarks. Other product and company names

Table of Contents

1.0 INTRODUCTION ...................................

2.0 SOFTWARE INSTALLATION ........................

3.0 HARDWARE INSTALLATION .......................

4.0 CABLING .........................................

5.0 DATA REGISTERS .................................

6.0 SPECIFICATIONS ..................................

7.0 ELECTRONICS AND INTERFACING .................

1
1
2

23.1 BOARD SETUP ..................................

23.2 BASE ADDRESS ..................................

4

44.1 INTRODUCTION .................................

44.2 CONNECTOR DIAGRAM ..........................

6
7
8

87.1 UNCONNECTED INPUTS FLOAT ....................

97.2 TTL TO SOLID STATE RELAYS ......................

97.3 VOLTAGE DIVIDERS ..............................

107.4 LOW PASS FILTERS DE-BOUNCE INPUTS ...........

This page is blank.

1.0 INTRODUCTION

The PC104-DI48 is designed to have the best quality and lowest cost of any digital
input board.

The PC104-DI48 conforms to the connector pin specification of all the PC104-DIO48
digital boards and CIO-Dxx48, 96 and 192 family digital boards, so may be used in
place of one another without changing cabling or connectors.

These products are supported by Universal Library programming library.

2.0 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
InstaCal
you all available options, how to configure the various switches and jumpers (as
applicable) 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.

TM

program provided as part of your software package. InstaCalTM will show

Please refer to the Extended Software Installation Manual regarding the installation

TM

and operation of InstaCal

. The following hard copy information is provided as a

matter of completeness, and will allow you to set the hardware configuration of the

TM

board if you do not have immediate access to InstaCal

and/or your computer.

Details for setting of the switches are in the following section.

1

3.0 HARDWARE INSTALLATION

3.1 BOARD SETUP

The PC104-DI48 is setup at the factory with BASE ADDRESS= 300h (768 decimal).

Open your PC (after turning off the power) and install the board. Leave the address
switches as they were set at the factory or refer to the information below to change the
settings. After the board is installed and the computer is closed up, turn power on.

PC104-DI48 is a dedicated 48 line digital input board built up of logic chips. There
are no control registers. The input pins present a single LSTTL load.

3.2 BASE ADDRESS

The PC104-DI48 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. It receives and places data on eight data lines.

Base address is the most important user-selectable item of the PC104-DI48. The base
address is the starting location that software reads from when communicating with the
PC104-DI48. DIP switches (Figures 3-1 and 4-2) are used to set the base address (0).
Each switch position corresponds to one of the PC bus address lines. By placing the
switch down, the address decode logic adds that value to the base address.

A base address is constructed by
calculating the HEX or decimal
number which will be the address
the board will respond to. For
example, in Figure 3-1, switches 1
and 2 are down, all others are up.

Switch 1 = 200h (512d) and switch
2 = 100h (256d). Added together
they equal 300h (768 decimal).

Certain addresses are used by the PC, others are free and may be used by the
PC104-DI48 and other expansion boards. We recommend that BASE = 300h (768D)
be tried first. Refer to Table 3-1 below for PC I/O addresses.

1 2 3 4 5 6 7

Figure 3-1. Base Address Switches (300h Shown)

2

SW H EX
1 200
2 100
3 80
4 40
5 20
6 10
7 08

Table 3-1. I/O Addresses

FUNCTIONHEX

RANGE

FUNCTIONHEX

RANGE

EGA2C0-2CF8237 DMA #1000-00F
EGA2D0-2DF8259 PIC #1020-021
GPIB (AT)2E0-2E78253 TIMER040-043
SERIAL PORT2E8-2EF8255 PPI (XT)060-063
SERIAL PORT2F8-2FF8742 CONTROLLER (AT)060-064

070-071

CMOS RAM & NMI MASK (AT)

PROTOTYPE CARD300-30F
PROTOTTYPE CARD310-31FDMA PAGE REGISTERS080-08F
HARD DISK (XT)320-32F8259 PIC #2 (AT)0A0-0A1
PARALLEL PRINTER378-37FNMI MASK (XT)0A0-0AF
SDLC380-38F8237 #2 (AT)0C0-0DF
SDLC3A0-3AF80287 NUMERIC CO-P (AT)0F0-0FF
MDA3B0-3BBHARD DISK (AT)1F0-1FF
PARALLEL PRINTER3BC-3BFGAME CONTROL200-20F
EGA3C0-3CFEXPANSION UNIT (XT)210-21F
CGA3D0-3DFBUS MOUSE238-23B
SERIAL PORT3E8-3EFALT BUS MOUSE23C-23F
FLOPPY DISK3F0-3F7PARALLEL PRINTER270-27F
SERIAL PORT3F8-3FFEGA2B0-2BF

The PC104-DI48 BASE switch may be set for address in the range of 000-3FC so it
should not be hard to find a free address area for you PC104-DI48. If you are not
using IBM prototyping cards or some other board which occupies these addresses,
then 300-31F HEX are free to use.

Addresses not specifically listed, such as 390-39F, are not reserved and may be
available. Check your computer for other boards which may use I/O addresses.

3

4.0 CABLING

4.1 INTRODUCTION

The PC104-DI48 connector is a standard 50 pin header connector (Figure 4-2). A
cable with mating connectors (C50FF-#) can be purchased from Measurement
Computing Corporation.

4.2 CONNECTOR DIAGRAM

The PC104-DI48 connector is a 50-pin header-type connector.

GND
PC1 BIT 0
PC1 BIT 2
PC1 BIT 4
PC1 BIT 6
PB1 BIT 0
PB1 BIT 2
PB1 BIT 4
PB1 BIT 6
PA1 BIT 0
PA1 BIT 2
PA1 BIT 4
PA1 BIT 6
PC2 BIT 0
PC2 BIT 2
PC2 BIT 4
PC2 BIT 6
PB2 BIT 0
PB2 BIT 2
PB2 BIT 4
PB2 BIT 6
PA2 BIT 0
PA2 BIT 2
PA2 BIT 4
PA2 BIT 6

+5V
PC1 BIT 1
PC1 BIT 3
PC1 BIT 5
PC1 BIT 7
PB1 BIT 1
PB1 BIT 3
PB1 BIT 5
PB1 BIT 7
PA1 BIT 1
PA1 BIT 3
PA1 BIT 5
PA1 BIT 7
PC2 BIT 1
PC2 BIT 3
PC2 BIT 5
PC2 BIT 7
PB2 BIT 1
PB2 BIT 3
PB2 BIT 5
PB2 BIT 7
PA2 BIT 1
PA2 BIT 3
PA2 BIT 5
PA2 BIT 7

PORT 1
BASE + 0, 1, 2

PORT 2
BASE + 4, 5, 6

Figure 4-1. 50-Pin Connector

4

Figure 4-2. Base Address Switches and Pin 1 Locations

5

5.0 DATA REGISTERS

Each PC104-DI48 is composed of parallel input chips. Each address has one input
buffer that senses eight input pins. The ports are arranged in sets of three, with an
intervening N/A (not used) address area. This scheme allows compatibility with
software written to control 82C55 based boards when the 82C55 is used as all inputs.
(On those boards every fourth address contains a control register.)

The first address, or BASE ADDRESS, is determined by setting the base address
switches on the board. To read data from an input register, a byte is read representing
the status of all eight digital input lines. The individual bits are decoded as a (0) or a
(1). Data read from registers must be analyzed to determine which bits are on or off.

The registers and their function are listed on the following table. Each register has
eight bits of data.

WRITE FUNCTIONREAD FUNCTIONADDRESS

NonePort 1A DataBASE + 0
NonePort 1B DataBASE + 1
NonePort 1C DataBASE + 2

NoneBASE + 3

NonePort 2A DataBASE + 4
NonePort 2B DataBASE + 5
NonePort 2C DataBASE + 6

NoneBASE + 7

PORTS 1A and 2A DATA
BASE ADDRESS + 0, and +4

PORTS 1B and 2B DATA
BASE ADDRESS + 1, and +5

PORTS 1C and 2C DATA
BASE ADDRESS + 2, and +6

01234567

A0A1A2A3A4A5A6A7

01234567

B0B1B2B3B4B5B6B7

01234567

C0C1C2C3C4C5C6C7

6

POWER CONSUMPTION

+5V Supply 250 mA typical / 325 mA max.
+12V Supply None.

−12V Supply None.

DIGITAL INPUT

Digital Type Input: 74LS373
Configuration 6 banks of 8 bits each, input only
Number of channels 48 inputs
Input High 2.0 volts min, 7 volts absolute max
Input Low 0.8 volts max, −0.5 volts absolute min
Miscellaneous Locations provided for installation of pull-up or

ENVIRONMENTAL

Operating Temperature 0 to 70°C
Storage Temperature −40 to 100°C
Humidity 0 to 90% non-condensing

6.0 SPECIFICATIONS

pull-down resistors.

7

7.0 ELECTRONICS AND INTERFACING

This short introduction to the electronics, most often needed by digital I/O board
users, covers a few key concepts.

7.1 UNCONNECTED INPUTS FLOAT

Unconnected inputs will float. If you are using the PC104-DI48 board for input, and
have unconnected inputs, ignore the data from those lines.

For example, if you connect bit A0 and not bit A1, do not be surprised if A1 stays
low, stays high or tracks A0... It is unconnected and so is unspecified. The input
buffer is not malfunctioning. In the absence of a pull-up/pull-down resistor, any input
to a PC104-DI48 which is unconnected, is unspecified.

You do not have to tie input lines, and unconnected lines will not affect the
performance of connected lines. Just make sure that you mask out any unconnected
bits in software.

An alternative to masking inputs is to define the state of unused inputs by using
pull-up or pull-down resistors. There are locations on the board for installation of
these resistors marked RN1 thro ugh RN6 . T he lo ca tion asso ci ated with FIRST P ORT
A (the port at Base +0) is RN1. The lo cation for FIRST PORT B (the port at B ase
+1) is RN2. FIRST PORT C (Base +2) is RN3; SECOND PORT A (Base +4) is
RN4; SECOND PORT B (Base +5) is RN5; SECOND PORT C (Base +6) is RN6.

A 10Kohm, eight-resistor SIP has all its resistors connected on one end to a single
common pin. The common pin is marked with a dot and is at one end of the SIP. The
other ends connect to eight in-line pins.

The SIP can be installed to pull-up or pull-down. At each location there are 10 holes
in a line. One end of the line is marked HI; the other end LO. The eight holes in the
middle are connected to the eight lines of a port, A, B, or C.

To pull-up lines, orient the SIP with the common pin (dot) in toward the HI end; to
pull-down, install the resistor with the common pin in the LO hole.

Carefully solder the SIP in place.

A resistor value of 10K is recommended. Use other values only if you have
determined the necessity for doing so.

8

7.2 TTL TO SOLID STATE RELAYS

Many applications require digital inputs monitor AC and DC voltages. High AC and
DC voltages cannot be applied directly by the TTL digital lines.

Solid State Relays, such as those available from Measurement Computing Corp. allow
control and monitoring of high AC and DC voltages and provide 400V isolation.
Solid State Relays (SSRs) are recommended for interfacing to high voltages.

The most convenient way to use solid state relays is to purchase a Solid State Relay
Rack. SSR Racks are available from Measurement Computing Corp.

7.3 VOLTAGE DIVIDERS

An alternative method of measuring a signal which varies over a range greater than the
input range of a digital input, is to use a voltage d ivider. When correctly designed, it
can drop the voltage of the input signal to a safe level the digital input can accept.

Ohm's law states:

Voltage = Current x Resistance

Kirkoff's law states:

The sum of the voltage drops around a circuit will be equal to the voltage
drop for the entire circuit.

In a voltage divider, the voltage across one resistor in a series circuit is proportional to
the total resistance divided by the one resistor (see formula below).

The object in a voltage divider is to choose two resistors having the proportions of
the maximum voltage of the input signal to the maximum allowed input voltage.

The formula for attenuation is:

Attenuation = R1 + R2

R2

For example, if the signal varies between 0 and 20

2 = 10K + 10K

10K

R1 = (A-1) x R2

volts and you wish to measure that with an analog
input with a full scale range of 0 to 10 volts, the
attenuation (A) is 2:1 or just 2.

For a given attenuation, pick a resistor and call it
R2, the use this formula to calculate R1.

9

Digital inputs often require the use of voltage dividers. For example, if you wish to
measure a digital signal that is at 0 volts when off and 24 volts when on, you cannot
connect that directly to a digital input. The voltage must be dropped to 5 volts max
when on. The attenuation is 24:5 or 4.8.

Using the equation above, if R2 is 1K, R1 = (4.8−1) x 1000 = 3.8K.

Remember that a TTL input is 'on' when the input voltage is greater than 2.5 volts.

NOTE

The resistors, R1 and R2, are going to dissipate power in the divider
circuit according to the equation W = I
Voltage/Resistance). The higher the value of the resistance (R1 +
R2), the less power dissipated by the divider circuit. Here is a
simple rule:

For attenuation of <5:1, no resistor should be less than 10K.

For attenuation of > 5:1, no resistor should be less than 1K.

2

x R; (Current (I) =

7.4 LOW PASS FILTERS DE-BOUNCE INPUTS

A low pass filter is placed on the signal wires between a signal and an A/D board. It
prevents frequencies greater than the cut-off frequency from entering the A/D board's
digital inputs.

The cut-off frequency is that frequency above which no variation of voltage with
respect to time may enter the circuit. For example, if a low-pass filter had a cut-off
frequency of 30 Hz, the kind of interference associated with line voltage (60 Hz)
would be mostly filtered out but a signal of 25 Hz would pass with less attenuation.

Also, in a digital circuit, a low-pass filter is often used to remove contact bounce noise
signals from a switch or a relay contacts.

A simple low-pass filter can be constructed from one resistor (R) and one capacitor
(C). The cut-off frequency is determined according to the formula:

Fc =

R = 1

1 Where π = 3.14...

2 π R C R = ohms

C = farads

Fc = cut-off frequency in cycles/second.

2π C Fc

10

EC Declaration of Conformity

Measurement Computing Corp.

We,

PC104-DI48

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:

, declare under sole responsibility that the product:

DescriptionPart Number
Digital input board

EU EMC Directive 89/336/EEC

compatibility.

EU 55022 Class B

characteristics of information technology equipment.

EN 50082-1

IEC 801-2

and control equipment.

IEC 801-3

measurements and control equipment.

IEC 801-4

equipment.

Carl Haapaoja, Director of Quality Assurance

: Electrostatic discharge requirements for industrial process measurement

: Radiated electromagnetic field requirements for industrial process

: Electrically fast transients for industrial process measurement and control

: Limits and methods of measurements of radio interference

: EC generic immunity requirements.

: Essential requirements relating to electromagnetic

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