2-8, Getting Started 11-19-01 Digital488 User’s Manual
My Listen Address (MLA)
When the Digital488 is addressed to listen in the F0 through F4 format, it accepts characters from the
active talker and interprets these characters as commands and command parameters. These commands are
explained in Chapter 3.
In the high-speed binary format (F5), the command interpreter is disabled. The Digital488 treats all bytes
received as data to be output to the Digital I/O ports. Each time it receives five bytes
or detects EOI
it pulses the Data Strobe for approximately 15 microseconds. Using the Digital488 data is expected I
n a PORT5, PORT4, PORT3, PORT2, PORT1 sequence. Using the Digital488/32/OEM data is expected
in a PORT4, PORT3, PORT2, PORT1 sequence.
If only two bytes are received, with EOI asserted on the second byte, the Digital488 will update PORT5
with the first byte received PORT4 with the second and pulse the Data Strobe.
If using Digital488/32/OEM will update PORT4 with the first byte received, and PORT3 with the second
and pulse the Data Strobe. Since the interface treats all received characters as data, the Status (Un)
command will not be recognized.
Device Clear (DCL and SDC)
In the F0 thru F4 formats, Device Clear resets the Digital488 to power on defaults and pulses the Clear
output line for approximately 50 microseconds.
In the high-speed binary format (F5), it enables the command interpreter and changes the format to F0. All
other parameters remain unchanged. In addition, the Clear output line is not pulsed by DCL or SDC when
the interface is in F5. This is the only programmable method to exit the F5 format.
Group Execute Trigger (GET)
When the Digital488 recognizes a GET, it pulses the Trigger output line for approximately 50
microseconds.
Interface Clear (IFC)
IFC places the Digital488 in the Talker/Listener Idle State and pulses the Clear output line for
approximately 50 microseconds.
Serial Poll Enable (SPE)
When Serial Poll Enabled, the Digital488 sets itself to respond to a serial poll with its serial poll status byte
if addressed to talk. When the serial poll byte is accepted by the controller, any pending SRQs are cleared.
The Digital488 will continue to try to output its serial poll response until it is serial poll disabled by the
controller.
Serial Poll Disable (SPD)
Disables the Digital488 from responding to serial polls by the controller.
Unlisten (UNL)
UNL places the Digital488 in the Listener Idle State.
Untalk (UNT)
UNT places the Digital488 in the Talker Idle State.
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