Fluke PM6681 S t a t u s B y t e, R e g i s t e r, S R Q, s ig n a, L o g ic a, l O R, Example

Using the Subsystems

request,

it

may

regularly

test

the

Example:

SRQ-line,

it

may

regularly

make

serial

*SRE￿16

poll or *STB?, or the controller may not

This sets bit 4 (16=24) in the service request

react at all. The preferred method is to

enable register (see Figure 6-8). This

use SRQ because it presents a minimum

makes

the

instrument

signal

SRQ

of disturbance to the measurement pro-

when a message is available in the

u

s

cess.

output queue.

it

t

Selecting Summary Message to Gen-

RQS/MSS

a

B

t

erate SRQ

The original status byte of IEEEs

e

le

is

488.1S

b

The counter does not generate any SRQ

u

ic

a

sent as a response to a serial poll, anditbit

D

by default. You must first select

which

t

t

a

y

B

ila

v r

6 means requested service, RQS.

summary message(s) from the status byte

a

r

b

register should give SRQ. You do

that

IEEE 488.2 added the *STB?s query and

S

e

m u

a

le

n

ila

a

with the

Service

Request Enable

com-

expanded the statusSbyte with a slightly

m

t

v

b

mand *SRE <bit mask>.

different bit 6, the MSS. This bit is true

io

s

u

t

a

A

n

a

t S

S

e

io

v

e

t

ic

g

A

r

e

s

r

a

u

t

a

s

t

v

e

n

s

r

e

e

q

t

e

s

e

o

D

e

p

R

a

v

e

Q

u

r

r

d

O

E

M

E

e

=

=

=

M

s

=

=

0

=

=

=

u

G

R

S

B

E

P

Q

S

S

V

U

V

t

E

O

R

S

E

A Q

A

o

R

M

E

N

D

M

t

p

u

t

u

e

o

e

in

t

h

t

a

in

r

e

t

le

is

g

e

R

R Q S

S e r

v ic e

S t a t u s B y t e

R e q

6

1

D R

E G 0

uOePsRtE S B QM UAE A V

G e n

e

r

a t

io

n

R e g i s t e r

1

M S S

21

6

8

4

2

1

2 8 3

S R Q

s ig n a

lS e r v ic e R e q u e s t E n a b

L o g ic a

l O R

Figure 6-7The status byte bits.

Status Subsystem 6-17