General Purpose Interface Bus (Gpib); Gpib Controls And Switches Diagram - Wavetek 75 Instruction Manual

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Paragraph 3.26.1
Figure 3-6. GPlB Controls and Switches
3.27 GENERAL PURPOSE INTERFACE BUS (GPIB)
Paragraphs 3.27 through 3.27.9are provided for readers
who wish further background information on the General
Purpose Interface Bus (GPIB). For specific Model 75 pro-
gramming information, refer to paragraph 3.28 through
3.29.3.
The GPlB interface is an implementation of IEEE
specification 488-1 978. It supports the following inter-
face functions which are described in detail in the
specification. Relevant aspects of these functions are
discussed in following paragraphs.
SHI Complete source handshake.
AH 1 Complete acceptor handshake.
T6 Basic talker.
TEO No extended talker.
L4 Basic listener.
SR1 Complete service request (software
select).
RLI Remotellocal and local lockout.
PPO No parallel poll capability.
DC1 Complete device clearlselective device
clear.
DT1 Complete device trigger capability.
E l Open collector drivers.
Instruments on the bus may have "talk" and "listen"
capabilities. The talk capability allows a device to send
data(such aserror message readings)out over the bus.
The listen capability allows a device to receive data (such
as device programming information) from the bus.
The GPlB consists of 16 negative true signal lines as
shown in figure 3-7. These 16 lines include 8 bidirectional
data lines, 3 handshake lines and 5 control lines. All
devices on the bus interface to these lines with passive
pull up and active pull down. Thus, any device may
"assert" a line by pulling it down to the logic low, or
"true" state. If nodevice is asserting the line, it is pulled
up to the logic high, or "false" state. (Only the controller
is allowed to assert certain lines.)
As shown in figure 3-7, devices connected to the bus may
be a LISTENER (only), TALKER (only), LISTENER1
TALKER or CONTROLLER. The Model 75 is both a talker
and a listener. More than one controller may be con-
nected to the bus, but only one controller may be hard
wired as SYSTEM CONTROLLER, and only one controller
at a time may assume the role of ACTIVE CONTROLLER.
Scans by Artekhfedia O 2006