Bus addresses…… 34, Rminators…… 34, Bus addresses – Measurement Computing Digital488/80A User Manual
Page 40: Bus terminators
• Selected Device Clear (
SDC
): In the
F0
through
F4
formats, Device Clear resets the Digital488/80A to
its power on default state, and pulses the Clear output line for approximately 50 microseconds.
If either channel is in the high-speed binary data format (
F5
), a
DCL
or
SDC
to either channel enables
the command interpreter on the channel in the
F5
mode, and then changes the format to
F0
. All other
parameters remain unchanged. In addition, the Clear output line is not pulsed by
DCL
or
SDC
when
either channel is in the
F5
mode. This is the only programmable method to exit the
F5
format.
• Serial Poll Disable (
SPD
): Disables the Digital488/80A from responding to Serial Polls by the
controller.
• Serial Poll Enable (
SPE
): When Serial Poll Enabled, the Digital488/80A 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
SRQ
s are cleared. The Digital488/80A will continue to try to output its
Serial Poll response until it is Serial Poll Disabled by the controller.
• Unlisten (
UNL
):
UNL
places the Digital488/80A in the Listener Idle State.
• Untalk (
UNT
):
UNT
places the Digital488/80A in the Talker Idle State.
Bus Addresses
The IEEE 488 interface standard permits up to 15 devices to be configured within one system. Each of
these devices must have a unique address to avoid confusion. In a similar fashion, every building in town
has a unique address to prevent one home from receiving another home's mail. Exactly how each device's
address is set is specific to the product's manufacturer. Some are set by DIP switches in hardware, others
by software. To determine how to set the Digital488/80A addresses, refer to Chapter 2: Digital488/80A
Setup.
IEEE 488 bus addresses are sent with bus (multiline) commands from the Active Controller. These
commands include My Listen Address (
MLA
), My Talk Address (
MTA
), Talk Address Group (
TAG
), and
Listen Address Group (
LAG
).
Bus Terminators
The factory default setting for the Digital488/80A output terminating character is Carriage Return, Line
Feed (
CR LF
). If necessary, it can be changed using the Terminator (
Y
) command. To save the new
setting as the power-up default, it must be saved with the Save Configuration (
S
) command. Then this new
setting can be loaded with the Recall Configuration (
O
) command. For more information on these
commands, refer to Chapter 6: Digital488/80A Commands.
The only input terminating character accepted by the Digital488/80A is the Execute (
X
) command. All
other input terminators are ignored.
34 Digital488/80A Operation
Digital488/80A User's Manual