the talk address is transmitted and false when the
status byte is read.
SPD (Serial Poll Disable) - The SPD command
is sent by the controller to remove all instrumentation
on the bus from the serial poll mode.
4-8-3. Addressed Commands
Addressed commands are multiline commands that
must be preceded by a listen command derived from
the device’s primary address before the instrument
will respond. Only the addressed device will respond
to each of these commands:
SDC (Selective Device Clear) - The SDC command
performs essentially the same function as the DCL
command except that only the addressed device will
respond. This command is useful for clearing only
a selected instrument instead of all devices simul-
taneously. Model 8020 will return to the default
conditions listed in Tables 3-1 and 4-4 when re-
sponding to an SDC command. To transmit the SDC
command, the controller must perform the following
steps:
1. Set ATN true.
2. Address the Model 8020 to listen.
3. Place the SDC command on the data bus.
GTL (Go To Local) - The GTL command is used
to remove the instrument from the remote mode of
operation. Also, front panel control operation will
usually be restored if the LLO command was pre-
viously sent. To send the GTL command, the controller
must perform the following sequence:
1. Set ATN true.
2. Address the Model 8020 to listen.
3. Place the GTL command on the bus.
NOTE
The GTL command does not remove
the local lockout state. With the local
lockout condition previously set, the
GTL command will enable front panel
control operation until the next time
a listener address command is re-
ceived. This places the Model 8020
in the local lockout state again.
GET (Group Execute Trigger) - The GET command
is used to trigger or arm devices to perform a
specific task depends on device configuration. Al-
though GET is considered to be an addressed
command, many devices respond to GET without
being addressed. Using the GET command is only
one of several methods that can be used to initiate
a trigger. More detailed information on triggering can
be found in Section 3 of this manual. To send GET
command over the bus, the controller must perform
the following sequence:
1. Set ATN true.
2. Address the Model 8020 to listen.
3. Place the GET command on the data bus.
GET can also be sent without addressing by omitting
step 2.
Mode Default Status
Display/Modify D0 Display frequency
Sweep Mode S0 Sweep mode off
Offset Mode O0 Offset mode off
Operating Mode V0 VCO mode off
Gated Mode G0 Gated mode off
Trigger Mode T0 Trigger mode off
Pulse Mode (Model 8021) P0 Pulse mode off
AM Mode (Model 8022) A0 Am mode off
Output Mode (Model 8021) C0 Pulse complement off; Ramp down off
St-by B0 Output stand-by off
Response Message Format X0 Response header OFF
Response Message Terminator Z0 New line(LF), END(EOI) terminator
Event Status Enable Mask *ESE0 No mask
SRQ Enable Register Mask *SRE0 No mask
Table 4-4. Default Conditions. (Status After SDC, DCL, or *RST )
IEEE-488.2 Operation Model 8020
Page 4-8
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