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Chapter 4 Remote Interface Reference
The SCPI Status Registers
The Status Byte Summary register is cleared when:
• Y o u e x e c u t e t h e
• Q u e r y i n g t h e S t a n d a r d E v e n t r e g i s t e r (
5 i n t h e S t a t u s B y t e s u m m a r y r e g i s t e r .
F o r e x a m p l e , 2 4 ( 8 + 1 6 ) i s r e t u r n e d w h e n y o u h a v e q u e r i e d t h e s t a t u s o f t h e
S t a t u s B y t e r e g i s t e r , Q U E S a n d M A V c o n d i t i o n s h a v e o c c u r r e d .
The Status Byte Enable register (Request Service) is cleared when:
• Y o u e x e c u t e t h e
• Y o u t u r n o n t h e p o w e r a n d h a v e p r e v i o u s l y c o n f i g u r e d t h e p o w e r s u p p l y
u s i n g t h e
• T h e e n a b l e r e g i s t e r w i l l n o t b e c l e a r e d a t p o w e r - o n i f y o u h a v e p r e v i o u s l y
c o n f i g u r e d t h e p o w e r s u p p l y u s i n g
Using Service Request (SRQ) and Serial POLL
Y o u m u s t c o n f i g u r e y o u r b u s c o n t r o l l e r t o r e s p o n d t o t h e I E E E - 4 8 8 s e r v i c e
r e q u e s t ( S R Q ) i n t e r r u p t t o u s e t h i s c a p a b i l i t y . U s e t h e S t a t u s B y t e e n a b l e
r e g i s t e r (
I E E E - 4 8 8 s e r v i c e r e q u e s t s i g n a l . W h e n b i t 6 ( r e q u e s t s e r v i c e ) i s s e t i n t h e S t a t u s
B y t e , a n I E E E - 4 8 8 s e r v i c e r e q u e s t i n t e r r u p t m e s s a g e i s a u t o m a t i c a l l y s e n t t o
t h e b u s c o n t r o l l e r . T h e b u s c o n t r o l l e r m a y t h e n p o l l t h e i n s t r u m e n t s o n t h e b u s
t o i d e n t i f y w h i c h o n e r e q u e s t e d s e r v i c e ( t h e i n s t r u m e n t w i t h b i t 6 s e t i n i t s
S t a t u s B y t e ) .
T h e r e q u e s t s e r v i c e b i t i s c l e a r e d o n l y b y r e a d i n g t h e S t a t u s B y t e u s i n g a n
I E E E - 4 8 8 s e r i a l p o l l o r b y r e a d i n g t h e e v e n t r e g i s t e r w h o s e s u m m a r y b i t i s
c a u s i n g t h e s e r v i c e r e q u e s t .
T o r e a d t h e S t a t u s B y t e s u m m a r y r e g i s t e r , s e n d t h e I E E E - 4 8 8 s e r i a l p o l l
m e s s a g e . Q u e r y i n g t h e s u m m a r y r e g i s t e r w i l l r e t u r n a d e c i m a l v a l u e w h i c h
c o r r e s p o n d s t o t h e b i n a r y - w e i g h t e d s u m o f t h e b i t s s e t i n t h e r e g i s t e r . S e r i a l
p o l l w i l l a u t o m a t i c a l l y c l e a r t h e " r e q u e s t s e r v i c e " b i t i n t h e S t a t u s B y t e
s u m m a r y r e g i s t e r . N o o t h e r b i t s a r e a f f e c t e d . P e r f o r m i n g a s e r i a l p o l l w i l l n o t
a f f e c t i n s t r u m e n t t h r o u g h p u t .
C a u t i o n
The IEEE-488 standard does not ensure synchronization between your bus controller
program and the instrument. Use the *OPC? command to guarantee that commands
previously sent to the instrument have completed. Executing a serial poll before a
*RST, *CLS, or other commands have completed can cause previous conditions
to be reported.
*CLS
( c l e a r s t a t u s ) c o m m a n d .
*SRE 0
c o m m a n d .
*PSC 1
c o m m a n d .
* SRE
c o m m a n d ) t o s e l e c t w h i c h s u m m a r y b i t s w i l l s e t t h e l o w - l e v e l
* ESR?
c o m m a n d ) w i l l c l e a r o n l y b i t
*PSC 0
.
4
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