Tektronix DC 5010 Anleitung Seite 73

Operating Instructions-DC 501 0
The talker $'unction goes to its idle state when the instru- LLO-Local Lockout
ment receives the UNT command. In this state, the instru-
ment cannot output data via the GPIB.
In response to LLO, the instrument goes to a lockout
state-from LOCS to LWLS or from REMS to RWLS.
The ADDRESSED light is off when both the talker and
listener functions are idle, If the instrument is either talk ad-
dressed or listen addressed, the light is on.
IFC-Interface Clear
This uniline message has the same effect as both the
UNT and UNL messages. The front panel ADDRESS light is
off.
DCL-Device Clear
REN-Remote Enable
If REN is true, the instrument goes to a remote state
(from LOCS to REMS or from LWLS to RWLS) when its
listen address is received. REN false causes a transition
from any state to LOCS; the instrument stays in LOCS as
long as REN is false.
A REN transition may occur after message processing
has begun. In this case execution of the message being
processed is not affected by a transition.
The Device Clear message reinitializes communication
between the instrument and controller. In response to DCL, GTL-Go To Local
the instrument clears any input and output messages and
any unexecutsd settings in the Pending Settings Buffer.
Only instruments that are listen addressed respond to
Also cleared are any errors or events waiting to be reported,
GTL by going to a local state. Remote-to-local transitions
caused by GTL do not affect the execution of the message
except the power-on event. If the SRQ line is asserted for
being when GTL was
any reason other than power-on, when DCL is received the
SRQ is unasserted.
SDC-Selected Device Clear
This message performs the same function as DCL; how-
ever, only instruments that are listen addressed respond to
-
SDC.
GET-Group Execute Trigger
The instrurnent responds to GET only if it is listen ad-
dressed and the instrument device trigger function has been
enabled by the Device Trigger command (DT). The GET
message is ignored and an SRQ generated if the DT func-
tion is disabled (DT OFF), the instrument is in the local state,
or if a message is being processed when GET is received.
SPE-Serial lPoll Enable
SPD-Serial lPoll Disable
Remote-Local Operation
The preceding discussion of interface messages de-
scribes the state transitions caused by GTL and REN. Most
front panel controls cause a transition from REMS to LOCS
by asserting a message called return-to-local (rtl). This tran-
sition may occur during message execution; but in contrast
to GTL and REN transitions, a transition initiated by
rtl
does
affect message execution. In this case, the instrument gen-
erates an error if there are any unexecuted setting or oper-
ational commands. Front panel controls that only change
the display (like ID) do not affect the remote-local
states-only front panel controls that change settings as-
sert rtl. Rtl is unasserted after processing the front panel
control change.
Local State (LOCS)
The SPE message enables the instrument to output In LOCS, instrument settings are controlled by the opera-
serial poll status bytes when it is talk addressed. The SPD tor via front panel controls. When in LOCS, only bus corn-
message switches the instrument back to its normal oper- mands that do not change instrument settings are executed
ation of sending the data from the Output buffer. (query-output commands); all other bus commands (setting
and operational) generate an error since their functions are
under front panel control.
MLA-My Listen Address
MTA-My Tallk Address
The primary listen and talk addresses are established by
With Lockout State (LWLS)
the instrumenits GPlB address (internally set). The current
setting of the GPlB address is displayed on the front panel The instrument operates the same as it does in LOCS,
when the INST ID button is pressed. except that rtl will not inhibit a transition to RWLS.
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