HP 3468A - Page 78

SRO (Cont'd)
Example 2. Front Panel SRO
The front panel SRO feature of the 3468A provides you with a way of manually
interrupting the controller from the multimeter front panel. This feature is enabled
by setting bit 4 of the SRO mask, command “M20”. Once this is done, pressing
the 3468A front panel SRO key causes the 3468A to request service (SRQ) from
the controller. The SRO annunciator turns on in the display until the controller
responds by doing a serial poll or the CLEAR command.
The
following
program
shows
how
easily
this
can
be
accomplished.
| FRUNT PANEL SRe EXAMPLE
' -he- $5 VERSION
A | 3463R AT ADDRESS 9at
46 REMOTE 9
Sa QUTPUT 9@1 : "Mea"
6@ ON INTR 9 GOSUB 1868
7a@ ENABLE INTR 958
68 1 The body of the Program 30
es here
996 END
19G@ P=SPOLL¢3a1)
1410 IF BIT¢P:.4) THEN DISP "SRG
key Pressed"
1926 RETURN
Line
50
60
70
80-990
1000
1010
1020
74
Description
The “M20” statement sets the 3468A to
respond to the front panel SRQ key.
This tells the computer where to go (line
1000) when an SROQ interrupt occurs.
ENABLE INTR actually allows the controller
to respond to interrupts.
These lines contain the body of the pro-
gram.
SPOLL returns 3468A status byte to
variable P, It also clears the status register.
Bit 4 of the status byte (P) is checked to
make sure it is a” 1”. If it is, the message
SRQ KEY PRESSED is displayed. If it isn’t,
then something else caused the interrupt.
This line returns program control to where
it was interrupted.