Measurement Computing Analyzer488 - Manual (Page 56)

Section 3 Front Panel Operation
3.10
The final examples use the Analyzer488 as an active controller connected to a
Keithley Instruments Model 196 System Digital Multimeter.
3.7.1 Controlling Bus Management and Bus Data Lines
Run the KYBDCTRL keyboard controller program, and turn the
Analyzer488 on. The front panel display will show a typical bus display:
SRQ IFC
REN ATN
EOI LOCATION MESSAGE
BUS LED on
BUS ACG00 00
¼
The front panel [EOI], [ATN], [SRQ], [REN], and [IFC]
keys are used to assert and unassert bus management lines. The
corresponding LED indicators show whether the Analyzer488 is
asserting (LED on) or unasserting (LED off) the lines. The EOI, ATN,
SRQ
, REN, and IFC digits on front panel display show the actual state
of the bus management lines. A • indicates that the line is asserted and
a blank indicates that it is unasserted.
The driven state, as shown by the keyboard LED indicators, and
the actual state, as shown by the digits on the front panel display, might
not be the same. If, for instance, the Analyzer488 is trying to unassert
a line (ATN LED off) and the controller is asserting the Attention line,
the LED indicator for that line will be off, but the front panel digit for
ATN
will be • , showing that the line really is asserted.
The -MESSAGE- area on the front panel display shows the state
of the bus data lines. When the Analyzer488 is in the Talk state (TALK
LED is on), bus data lines are driven by the hexadecimal keys, [0] -
[F]
, and the [
↑] and [↓] cursor keys. The actual bus state shown in
the -MESSAGE- area may not be the same as the driven state. For
instance, two devices may be driving the bus at the same time. If the
actual bus state is different from the driven state, the bus data in the -
MESSAGE-
area will flash. If hexadecimal format is used, the
hexadecimal value will flash. If binary format is used, the digits that
represent the individual lines that are different will flash.