Ieee-488 Bus Operation - Keithley 7021 Instruction Manual

Perform the following steps to configure the mainframe to
display the digital input channels.
1. Press the CARD CONFIGURATION key to display the
CARD CONFIG MENU.
2. Use the and keys to place the cursor on READ-I/
O-CARD and press ENTER.
Model 7001 mainframe — The real-time state (on or off)
of each input channel is provided on the first row of the
display. Only digital I/O input channels are displayed.
Model 7002 mainframe — The real-time state (on or
off) of each input channel is provided on the first row of
the appropriate LED display grid. Use the TYPE option
of the CARD CONFIG MENU if you do not know
which slot the card is installed in.
3. Use the EXIT key to exit from the "read input channels"
display mode.
NOTE
With input channels displayed, you can
turn off (open) all other channels by press-
ing OPEN ALL.

IEEE-488 bus operation

Bus operation is demonstrated using Microsoft QuickBASIC
4.5, the Keithley KPC-488.2 (or Capital Equipment Corpo-
ration) IEEE interface and the HP-style Universal Language
Driver (CECHP). Refer to "QuickBASIC 4.5 Programming"
in the mainframe manual for details on installing the Univer-
sal Language Driver, opening driver files and setting the in-
put terminal. Program statements assume that the primary
address of the mainframe is 07.
Turning channels on and off
The following SCPI commands are used to turn multiplexer
and digital I/O output channels on and off:
Turn on specified channels
:CLOSe <list>
Turn off specified (or all) channels.
:OPEN <list>|ALL
The following program statement turns on channels 1!1, 1!4
through 1!6, and the channels that make up channel pattern
M1.
PRINT #1, "output 07; clos (@ 1!1, 1!4:1!6, M1)"
Notice that the colon (:) is used to separate the range limits.
Either of the following statements turns off channels 1!1, 1!4
through 1!6, and the channels of M1:
PRINT #1, "output 07; open (@ 1!1, 1!4:1!6, M1)"
PRINT #1, "output 07; open all"
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Scanning output channels
There are many commands associated with scanning. How-
ever, it is possible to configure a scan using as little as four
commands. These commands are listed as follows:
*RST
:TRIGger:COUNt:AUTo ON
:ROUTe:SCAN <list>
:INIT
The first command resets the mainframe to a default scan
configuration. The second command automatically sets the
channel count to the number of channels in the scan list, the
third command defines the scan list, and the fourth command
takes the Model 7001/7002 out of the idle state.
The following program fragment will perform a single scan
of channels 1 through 4 of slot 1 and the channels that make
up channel pattern M1:
PRINT #1, "output 07; *rst"
PRINT #1, "output 07; trig:coun:auto on"
PRINT #1, "output 07; scan (@ 1!1:1!4, M1)"
PRINT #1, "output 07; init"
The first statement selects the *RST default configuration for
the scan. The second statement sets channel count to the
scan-list-length (5). The third statement defines the scan list,
and the last statement takes the mainframe out of the idle
state. The scan is configured to start as soon as the :INIT
command is executed.
When the above program fragment is run, the scan will be
completed in approximately 240 milliseconds (3msec delay
for channel closures and 3msec delay for each open), which
is too fast to view from the front panel. An additional relay
delay can be added to the program to slow down the scan for
viewing. The program is modified by adding a statement to
slow down the scan. Also, a statement is added to the begin-
ning of the program to ensure that all channels are open be-
fore the scan is started. The two additional statements are
indicated in bold typeface.
PRINT #1, "output 07; open all"
PRINT #1, "output 07; *rst"
PRINT #1, "output 07; trig:coun:auto on"
PRINT #1, "output 07; trig:del 0.5"
PRINT #1, "output 07; scan (@ 1!1:1!4, M1)"
PRINT #1, "output 07; init"
The first statement opens all channels, and the fourth state-
ment sets a 1/2 second delay after each channel closes.
Operation
5-5