Measurement Computing Digital488 - Manual (Page 27)

Section 2 Getting Started
2.11
2.4.2 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 Section 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. Data is expected in a
PORT5, 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. Since the interface treats all received
characters as data, the Status (Un) command will not be recognized.
2.4.3 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.
2.4.4 Group Execute Trigger (GET)
When the Digital488 recognizes a GET, it pulses the Trigger output
line for approximately 50 microseconds.