Universal Commands - Keithley 705 Instruction Manual

4. IFC (Interface Clear)-The IFC command sets the bus to a
known state by setting the IFC line (true).
5. SRQ (Service Request)-The SRQ line is pulled low by an
external device thereby informing the controller the device
requires service. The Model 705 implements this command
when in the appropriate bus response mode, as stated in
paragraph 3.5.3,
front panel controls (except POWER) are locked out. The
REN bus line must be low (true) before the instrument
responds to an LLO command.
Programming Example-This sequence is automatically
performed by the HP-85 when the following statements are
entered into the keyboard:
REMOTE 717 (END LINE)
3.4.2 Universal Commands
LOCAL LOCKOUT 7 (END LINE)
The IEEE-488 universal commands are sent when the ATN line
is low (true). There are six universal commands and their effect
on the Model 705 operation is described as follows:
1. DCL (Device Clear)-The DCL command is used to clear
the Model 705 setting it to a known state. Program memory
is cleared of all previously stored data when a DCL or SDC
command is received. The buffer is set to location one.
NOTE
To get the Model 705 out of LLO refer to para-
graph 3.4.3 step 3.
Programming Example-Using front panel controls enter
five channels on the Model 705 and select the continuous pro-
gram mode. Now enter the following statements into the
HP-85:
REMOTE 717 (END LINE)
CLEAR 7 (END LINE)
When END LINE is pressed the second time, the Model 705 is
set to its power-up default conditions which are listed in Table
3-5.
3. SPE (Serial Poll Enable)--The serial poll enable sequence is
used to obtain the Model 705 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:
A. The controller sets the ATN line true,
B. The SPE command is placed on the bus by the con-
troller.
C. The Model 705 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.
2. LLO (Local Lockout)-The LLO command is sent by the
controller to remove the Model 705 from the local operating
mode. Once the instrument receives the LLO command all
Programming Example-The HP-85 SPOLL statement
automatically performs the serial polling sequence. To demon-
strate serial polling momentarily power the unit down and enter
Table 3-5. Power-Up Default Values
Mode
Poles
Display Channel
Channel Displayed
Date Format
First Channel
Prefix
Channel Settle Time
ROM and LED Test
EOI
Set Last Channel
SRQ
Open Channel
Program
Trigger Mode
Interval Time
Terminator
__-
Value
A2
BOO1
DO
EO
Fl
GO00
HOOO.O1O
Jl
KO
Ll
MOO0
Nl
PO
Q
R
S
T6
U
V
w000.010
status
2-Pole Configuration
Display Channel One
Display Channel Mode
American Date Format
Set First Channel
Channel Data Transmitted with Prefix
Channel Settle Time = IOmsec
Check ROM and LEDs
EOI sent during last byte
Last Channel set to one.
Send no SRQ
Channel one open.
Step Program Mode
Previously programmed state.
Start on External.
Previously programmed state.
Previously programmed state.
Interval time set to IOmsec.
(CR)(LF)
3-6