Addressed Commands - Keithley 706 Instruction Manual

feet. This is, of course, because of the previous LLO com-
mand.
NOTE
To get the Model 706 out of the local lockout
condition send a GTL (Go To Local) command,
refer to paragraph 3.4.3 step 3.
3. SPE (Serial Poll Enable)-The serial poll enable sequence
is used to obtain the Model 706 status byte. Usually, the
serial polling sequence is used to determine which of
several devices has requested service over the SRQ line.
The serial polling sequence is conducted as follows:
_ ._c?. The controller sets the ATN line true.
B. The SPE command is placed on the bus by the con-
troller.
C. The Model 706 is addressed to talk.
D. The controller sets the ATN line false.
E. The instrument then places its status byte on the bus to
be read by the controller.
F. The controller then sets the ATN line low and places
SPD on the bus to end the serial polling sequence.
1. SDC (Selected Device Clear)-The SDC command per-
forms the same functions as the DCL command except
that only the addressed device responds. The instrument
returns to the set conditions listed in Table 3-5 when
responding to an SDC command. The program memory
of the addressed Model 706 is cleared of all previously
stored data when an SDC command is received. In addi-
tion the buffer and the display pointers are set to location
1.
SDC Programming Example-Using front panel controls
close channels 1 through 10 on the Model 706 and select the
single program mode. Now enter the following statements in-
to the HP-85.
REMOTE 718 (END LINE)
. .
CLEAR 712 (END LINE)
Notice that when the END LINE key is pressed after the
CLEAR 712 statement that the Model 706 did not respond to
the SDC because the command was sent with a primary ad-
dress of 12. Now enter the following statement into the
HP-85.
SPE Programming Example-The HP-85 SPOLL state-
CLEAR 718 (END LINE)
ment automatically performs the serial polling sequence. To
demonstrate serial polling, momentarily power the unit down
When the END LINE key is pressed after the CLEAR 718
and enter the following statements into the HP-85 keyboard.
statement, notice that the instrument returns to the SDC
default conditions listed in Table 3-5. Note, that, the program
REMOTE 718 (END LINE)
memory is cleared of previously stored data.
S=SPOLL (718) (END LINE1
DISP S (END LINE)
When the END LINE key is pressed after the S = SPOLL 718
statement, the computer performs the serial polling se-
quence. When the END LINE key is pressed after the DISP S
statement the status byte value is displayed on the CRT. The
status byte has a value of 0 with this example because all the
bits are set to 0.
2. GET (Group Execute Trigger)-The GET command is
used to trigger devices to perform a specific action that
depends on device configuration. Although GET is con-
sidered to be an addressed command, many devices res-
pond to GET without being addressed. Using the GET
command is only one of several methods that can be used
ti start or stop the Model 706 program operation.
4. SPD (Serial Poll Disable)-The controller automatically
sends the SPD command on the bus to end the serial poll-
ing sequence in SPE.
5. UNT (Untalkl-The controller sends the UNT command
to clear the bus of any talkers.
6. UNL (UnlistenI-The controller sends the UNL command
to clear the bus of any listeners.
3.4.3 Addressed Commands
Each of the addressed commands are sent to a specific
device on the bus. Each device is selected on the basis of its
primary address. The Model 706 responds to these com-
mands only if the primary address of the command is the
same as the primary address of the Model 706. All of the
following commands are implemented by addressing the
Model 706 to listen.
GET Programming Example-To help illustrate this exam-
ple first set the Model 706 to a known state, such as the
default conditions. Enter the following statements to do this.
REMOTE 718 (END LINE)
CLEAR 718 (END LINE)
When the END LINE key is pressed after the CLEAR 718
statement the Model 706 reverts to the set conditions listed in
Table 3-5. Now enter the following statement into the HP-85
to place the instrument in the continuous program mode and
start on GET trigger mode.
OUTPUT 718;"PTTw" (END LINE)
Where P2 is the command to set the instrument into the con-
tinuous program mode and T2 is the command to set the in-
strument to the start on GET mode. Now the instrument may
be triggered to start with the following statement:
' 3-7'