Agilent Technologies 4284A, Operation Manual

Page: 205 / 460

LOCAL LOCK OUT (LLO)
LOCAL LOCK OUT disables the LOCAL op eration ( 4284A :
Pressing 4 LCL 5) of all devices on the bus. After this command is
sen t y ou will b e unable to op erate the 4284A from the fron t panel.
Execute the LOCAL command to undo LOCAL LOCK OUT.
F or example:
LOCAL LOCKOUT 7
REMOTE
REMOTE sets the 4284A to the remote mo de. When this command
is sen t, fron t panel with the exception of 4
LCL
5 will b e disabled.
F or example:
REMOTE 717
SPOLL
SPOLL is the serial p olling command. SPOLL is used to place the
status b yte of the addressed instrumen t on the bus. The eigh t bits of
the status b yte can b e masked o and read to determine the 4284A's
op erating state.
F or example:
Var=SPOLL(717)
SERVICE REQUEST
The 4284A can send an SR Q (Service Request) con trol signal when it
requires the con troller to p erform a task. An SR Q can b e though t of
as an in terrupt whic h informs the con troller that information is ready
to b e transmitted, or that an error condition exists in the instrumen t.
When the 4284A sends an SR Q it also sets Bit 6 of the status b yte.
Bit 6 is the R QS (Request Service) bit, sometimes referred to as the
status bit in connection with p olling. When the 4284A is serially
p olled, it clears the R QS bit and the SR Q line, one of the v e
managemen t con trol lines of the system in terface. An y bit in the
status b yte can initiate an SR Q. The status b yte may b e masked b y
the user to determine whic h bits caused the 4284A to set the SR Q
line. F or more information on the status b yte, refer to \Status Byte".
TRIGGER (GET)
Enables the 4284A to the TRIGGER bus command. This command
may b e sen t to a selected device or to all devices addressed as
listeners on the GPIB bus. The 4284A m ust rst b e addressed as
a listener, second the trigger mo de is set to the BUS trigger mo de
b efore the trigger message is sen t.
F or example:
SEND 7;UNL MTA LISTEN 17
Remote Control 7-5