LOCAL LOCKOUT (LLO)
LOCAL LOCKOUT disables the LOCAL op eration (HP 4284A :
Pressing
4
LCL
5
) of all devices on the bus. After this command is sent
you will be unable to operate the HP 4284A from the front panel.
Execute the LOCAL command to undo LOCAL LOCKOUT.
For example:
LOCAL LOCKOUT 7
REMOTE
REMOTE sets the HP 4284A to the remote mode. When this
command is sent, front panel with the exception of
4
LCL
5
will be
disabled.
For example:
REMOTE 717
SPOLL
SPOLL is the serial p olling command. SPOLL is used to place the
status byte of the addressed instrument on the bus. The eight bits
of the status byte can b e masked o and read to determine the
HP 4284A's op erating state.
For example:
Var=SPOLL(717)
SERVICE REQUEST
The HP 4284A can send an SRQ (Service Request) control signal
when it requires the controller to p erform a task. An SRQ can
be thoughtofasaninterrupt which informs the controller that
information is ready to b e transmitted, or that an error condition
exists in the instrument. When the HP 4284A sends an SRQ it also
sets Bit 6 of the status byte. Bit 6 is the RQS (Request Service) bit,
sometimes referred to as the
status bit
in connection with polling.
When the HP 4284A is serially p olled, it clears the RQS bit and the
SRQ line, one of the ve management control lines of the system
interface. Any bit in the status byte can initiate an SRQ. The status
byte may b e masked by the user to determine which bits caused the
HP 4284A to set the SRQ line. For more information on the status
byte, refer to \Status Byte".
TRIGGER (GET)
Enables the HP 4284A to the TRIGGER bus command. This
command may b e sent to a selected device or to all devices addressed
as listeners on the HP-IB bus. The HP 4284A m
ust rst b e
addressed as a listener, second the trigger mode is set to the BUS
trigger mo de b efore the trigger message is sen
t.
For example:
Remote Control 7-5
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