Campbell Scientific CR10 CR10 Measurement and Control - Page 205

APPENDIX

ASCII:

Abbreviation for American Standard

Code

for

Information Interchange (pronounced

"askee").

A specific binary code

of

128

characters

represented by 7 bit binary numbers.

ASYNCHRONOUS: The transmission

of data

between

a

transmitting

and

a

receiving device

occurs as

a

series of zeros and

ones.

For

the

data

to

be "read" correctly,

the

receiving device

must

begin

reading

at

the

proper

point

in

the

series.

In

asynchronous communication, this

coordination

is

accomplished by having each

character

surrounded

by one

or

more start and

stop bits which designate

the

beginning and

ending

points

of

the

information (see

Synchronous).

BAUD

RATE:

The

speed of

transmission

of

information across

a serial

interface, expressed

in units of bits per

second.

For

example,

9600

baud refers

to

bits being

transmitted (or

received)

from

one piece of equipment

to

another at

a

rate

of

9600 bits per second.

Thus, a 7 bit ASCII

character

plus parity bit plus

1

stop

bit

(total 9 bits)

would

be

transmitted

in

9/9600 sec.

=

.94 ms or

about

1000

characters/sec. When communicating via

a

serial intedace,

the baud

rate settings of two

pieces of

equipment must

match each other.

DATA

POINT:

A data value

which

is

sent to

Final Storage as

the

result of an Output

Instruction.

Strings of

data

points output

at

the

same

time make

up Output

ArraYs.

EXECUTION

INTERVAL:

The

time

interval

between initiating

each

execution of a given

Program

Table.

lf

the

Execution Interual

is

evenly

divisible

into

24

hours (86,400 seconds),

the

Execution

lntervalwill

be synchronized with

24

hour time, so that the

table

is executed at

midnight and every

execution

interval thereafter.

The

table will

be executed for the first time at

the first

occurrence

of

the

Execution Interval

after

compilation.

lf

the

Execution Interval does

not

divide evenly into

24

hours, execution will

start on the

first even

second after compilation.

See Section OV4.3.1

for

information on the

choice of

an Execution

Interval.

EXECUTION

TIME:

The

time

required

to

execute

an

instruction or group of instructions.

lf

the

execution

time

of

a

Program Table

A.

GLOSSARY

exceeds the

table's

Execution Interval,

the

Program Table

will

be

executed

less

frequently

than programmed

(Section

OV4.3.1

and 8.9).

FINAL

STORAGE:

That

portion

of

memory

allocated

for

storing Output

Arrays.

Final

Storage may

be

viewed as

a

ring memory, with

the newest data being written over the oldest.

Data

in

Final Storage may be displayed using

the

*7

Mode or sent to

various

peripherals

(Sections 2, 3, and OV4.1).

GARBAGE:

The

refuse of

the

data

communication

world.

When

data

are sent

or

received incorrectly (and there

are

numerous

reasons

this

happens)

a

string

of

invalid,

meaningless

characters (garbage)

results.

Two

common

causes

are:

1)

a baud

rate mismatch

and 2) synchronous data being sent to

an

asynchronous device and vice versa.

HANDSHAKE, HANDSHAKING: The

exchange

of predetermined information

between two devices to assure each

that

it

is

connected to

the

other.

When

not used as

a

clock

line, the

CLIVHS

(pin

7)

line in the CR10

is

primarily

used to detect

the

presence

or

absence of peripherals such as

the

Storage

Module.

HIGH

RESOLUTION:

A

high resolution data

value

has

5

significant digits

and

may range

in

magnitude from +.00001 to

+99999.

A

high

resolution data

value

requires

2

Final Storage

locations (4

bytes).

All

Input

and

Intermediate

Storage locations

are

high

resolution.

Output

to

Final Storage defaults

to

low resolution; high

resolution

output

must be specified by

Instruction

78.

INDEXED

INPUT

LOCATION:

An

lnput

location entered as

an

instruction

parameter

may

be

indexed by keying "C" before it

is

entered by keying "A"; two

dashes

(--)

will

appear

at

the

right

of

the

display.

Within

a

loop

(lnstruction 87,

Section

12),

this

willcause

the

location

to

be incremented

with each

pass

through

the

loop.

Indexing

is

also

used with

Instruction 75 to cause

an

Input location, which

normally remains constant,

to be

incremented

with each

repetition.

A-1

Campbell Scientific CR10 CR10 Measurement and Control - Page 205

Appendix, Glossary

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