DATA PRECISION 5740 - BCD Option Functionality

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72-1002

Model

5740

COUNTER

reference

schematic,

includes

7

one-digit

display

units,

four

anode-driver

circuits

that

are

gated

with

the

digit

select

con

trol

signal

of

the

multiplexer,

two

BCD-

to-seven

segment

converters

for

the

groups

of

digit

data

transmitted

from

the

main

assembly,

resistor-coupled

ground

signal

for

the

selected

decimal

point,

and

tran

sistor

drivers

for

the

OVERFLOW

and

GATE

annunciators.

Note

that

the

decimal

points

of

the

two

more

significant

digits

(not

used

as

decimal

points)

are

used

as

the

annunciators

in

the

upper

left

(in

stead

of

lower

right)

location.

This

in

verted

position

of

the

display

is

com

pensated

for

by

suitable

selection

of

the

seven

segments

to

display

the

desired

digit.

3.12

BCD

OPTION

When

BCD

option

is

installed,

the

mea

sured

value

in

the

latching

registers

are

connected

to

the

PC

board

edge

terminals.

In

addition,

certain

status

and

control

signals

are

also

connected

to

the

PC

board

to

provide

user

capability

for

interpret

ing

the

values

and

for

printing

only

when

the

value

has

been

latched

between

mea

surements

.

As

shown

in

Drawing

75-1005

and

the

main

reference

schematic,

the

BCD

values

for

the

three

less

signifleant_digits

are

available

at

their

respective

latches

and

are

connected

directly

to

the

output

ter

minals.

The

four

more

significant

digits

are

de—multiplexed

and

transferred

to

independent

latches

Z201

to

220*+

in

the

BCD

option

components,

from

which

they

are

connected

to

the

edge

terminals.

Decimal

point

indicator

signals

are

developed

by

the

rotary

switch

action,

and

a

ground

level

at

any

position

se

lects

that

point.

Ungrounded

levels

are

held

at

+5V.

A

Print-Enable

status

signal

is

de

veloped

by

gating

the

instrument

Hold

and

Transfer

signals.

The

Print

Enable

is

a

low

level

when

either

the

Transfer

control

is

OFF,

or

when

the

Hold

signal

is

ON.

Thus,

the

user

may

recognize

when

the

BCD

data

is

static

during

the

Automatic

measuring

modes,

or

during

the

manual

measuring

modes,

respective

ly.

312

COPVBIOHT

U76

DATA

PRECISION

CORPORATION

PRINTED

IN

THE

U5.A.