HP 3478A Technical Manual page 119

A-1. Introduction A-1. Introduction
A-2. A-2. This appendix contains a This appendix contains a general description of
Hewlett-Packard Interface Bus Hewlett-Packard In terface Bus (HP-IB).
Hewlett-Packard's implementation of IEEE Standard Hewlett-Packard's implementation of IEEE Standard
488-1978, "Standard Digital Interface for Programmable 488-1978, "Standard Digital Interface for Programmable
Instrumentation". The information Instrumentation". The information is non-controller
dependent but, where appropriate, is dependent on dependent but, where appropriate, is dependent on the
3478A. 3478A.
A-3. A-3. General General HP-IB HP-IB Description Description
A-4. The Hewlett-Packard I A-4. The Hewlett-Packard Interface Bus (HP-
carefully defined interface which simplifies the integration carefully defined interface which simplifies the
of various instruments, calculators, and computers into of various instruments, calculators, and computers into
systems. systems. The interface prov The interface provides for messages
form to be transferred between two or form to be transferred between two or more HP-IB
compatible devices. compatible devices. A compatible A compatible device can be
instrument, calculator, computer, or peripheral device instrument, calculator, computer, or peripheral device
that is designed to be interfaced using the HP-IB. that is designed to be interfaced using the HP-IB.
A-5. A-5. The HP-IB is a para The HP-IB is a parallel bus of 16 active signa
grouped into three sets, according to grouped into three sets, according to function, to
interconnect up to 15 instruments. interconnect up to 15 instruments. A diagram of the
Interface Connections and Bus Structure is shown in Interface Connections and Bus Structure is shown in
Figure A-1. Figure A-1.
A-6. Eight Signal lines, term A-6. Eight Signal lines, termed as DATA Lines, are
the first set. the first set. The Data Lines are The Data Lines are used to transmit
the form of coded messages. the form of c oded messages. These messages ar
used to program the instrument function, transfer used to program the instrument function, transfer
measurement data, coordinate instrument operation, and measurement data, coordinate instrument operation, and
to manage the sys to manage the system. tem. This allows you to set
instrument and rea instrument and read its measurement d its measurement data.
Output of messages, in bit parallel byte serial form, are Output of messages, in bit parallel byte serial form, are
also transferred in the Data Lines. also transferred in the Data Lines. A 7-bit ASCII code
normally represents each piece of data. normally represents each piece of data.
A-7. Data is transferr A-7. Data is transferred by means of ed by means of an interlocking
"handshake" technique which permits data transfer "handshake" technique which permits data transfer
(asynchronously) at the rate of the slowest active device (asynchronously) at the rate of the
used in that particular used in that particular transfer. transfer. The three DATA BYTE
CONTROL lines coordinate the transfer and form the CONTROL lines coordinate the transfer and form the
second set of lines. second set of lines.
A-8. The remaining A-8. The remaining five GENERAL five GENERAL INTERFACE
MANAGEMENT lines are used to manage the devices MANAGEMENT lines are used to manage the devices
on the HP-IB. on the HP-IB. This includes act This includes activating all connected
devices at once, clear devices at once, clearing the interface, ing the interface, and others.
condensed description is available in the Condensed condensed description is available in the Condensed
Description of the Hewlett-Packard Interface Bus Description of the Hewlett-Packard Interface Bus
Manual, -hp- part Manual, -hp- part number 59401-90030 number 59401-90030. . The manual is
available through your local -hp- Sales and Service available through your local -hp- Sales and Service
general description of the
(HP-IB). HP-IB is HP-IB is
is non-controller
nterface Bus (HP-IB) is a IB) is a
integration
ides for messages in digital in digital
more HP-IB
device can be an
llel bus of 16 active signal lines
function, to
A diagram of the
ed as DATA Lines, are in in
used to transmit data in
These messages are e
This allows you to set-up the -up the
data. Input and Input and
A 7-bit ASCII code
an interlocking
slowest active device
The three DATA BYTE
INTERFACE
ivating all connected
and others. A A
The manual is
APPENDIX A APPENDIX A
Office. Office.
the A-9. HP-IB S A-9. HP-IB System
A-10. A-10. The following paragraphs d The following paragraphs define the terms
concepts used to describe HP-IB (Bus) concepts used to describe HP-IB (Bus) system
operations. operations.
the
A-11. HP-IB Syst A-11. HP-IB System Te
a. a. Address
device to specify which device will send information on device to specify which device will send information on
the HP-IB and which device(s) will receive that the HP-IB and which device(s) will receive that
information. Addressing may information.
hardwiring a device to only send information or only hardwiring a device to only send information or only
receive information. receive information.
an
b. b. Byte
digits (bits). digits (bits).
c. c.
l lines
Standard 488-1978. Standard 488-1978.
d. d.
performs in response to information sent over the HP-IB. performs in response to information sent over the
The action is characteristic of an individual device and The action is characteristic of an individual device and
may vary from device to device. may vary from device to device.
data in
e. e. Polling
controller to locate a device that needs to interact with controller to locate a device that needs to interact with
the controller. There are two typ the controller.
operational information about an individual device in operational information about an individual device in
the system. the system. The process must
device from which information is desired. device from which information is desired.
information about a group of information about a group of devices simultaneously.
The 3478A does not respond to a Parallel Pol The 3478A does not respond to a Parallel Poll. l.
A-12. A-12. Basic Device Basic Device Communication
A-13. A-13. Devices which com Devices which communicate along
bus can be classified into three basic categories: bus can be classified into three basic categories:
a. a. Talker Talker: : Any device that
over the HP-IB wh over the HP-IB when it has been addres
talker may be active at a time; usually the one that is talker may be active at a time; usually the one that is
currently directed currently directed to send data.
calculators and computers are generally talkers. calculators and computers are generally talkers.
A-1 A-1
ystem Overview Overview
em Terms rms
Address: The characters sent by a controlling : The characters sent by a controlling
Addressing may also be accom also be accomplished by
Byte: A unit of information consisting of 8 binary : A unit of information consisting of 8 binary
Device: A unit that is compatible with the IEEE Device : A unit that is compatible with the IEEE
Device Dependent: An action a device Device Dependent : An action a device
Polling: This process typically is used by a : This process typically is used by a
There are two types of polling, as follows:
1 1 . . Serial Serial Poll Poll: This method obtains one byte of : This method obtains one byte of
The process must be repeated for
2. 2. Parallel Poll Parallel Poll: This methods obtains : This methods obtains
Communication Capabilities
municate along the interface
Any device that is able to is able to send informat
en it has been addressed.
to send data. All HP-IB type
TM 11-6625-3071-14 TM 11-6625-3071-14
efine the terms and and
system
plished by
HP-IB.
es of polling, as follows:
be repeated for each each
devices simultaneously.
Capabilities
the interface
send information ion
sed. Only one Only one
All HP-IB type