Black Box IC095A User manual

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IEEE 488
Bus Extender
RECEIVE POWER
SEND
LISTEN
TALK
IEEE 488 PARALLEL
CUSTOMER
SUPPORT
INFORMATION
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AUGUST 2000
IC095A
IC096A
IEEE Bus Extender
IEEE Fiber Bus Extender

1
TRADEMARKS
TRADEMARKS USED IN THIS MANUAL
Any trademarks used in this manual are acknowledged to be the property of the trademark
owners.

2
IEEE 488 BUS EXTENDER AND IEEE 488 FIBER BUS EXTENDER
NORMAS OFICIALES MEXICANAS (NOM)
ELECTRICAL SAFETY STATEMENT
INSTRUCCIONES DE SEGURIDAD
1. Todas las instrucciones de seguridad y operación deberán ser leídas antes
de que el aparato eléctrico sea operado.
2. Las instrucciones de seguridad y operación deberán ser guardadas para
referencia futura.
3. Todas las advertencias en el aparato eléctrico y en sus instrucciones de
operación deben ser respetadas.
4. Todas las instrucciones de operación y uso deben ser seguidas.
5. El aparato eléctrico no deberá ser usado cerca del agua—por ejemplo, cerca
de la tina de baño, lavabo, sótano mojado o cerca de una alberca, etc..
6. El aparato eléctrico debe ser usado únicamente con carritos o pedestales que
sean recomendados por el fabricante.
7. El aparato eléctrico debe ser montado a la pared o al techo sólo como sea
recomendado por el fabricante.
8. Servicio—El usuario no debe intentar dar servicio al equipo eléctrico más allá
a lo descrito en las instrucciones de operación. Todo otro servicio deberá ser
referido a personal de servicio calificado.
9. El aparato eléctrico debe ser situado de tal manera que su posición no
interfiera su uso. La colocación del aparato eléctrico sobre una cama, sofá,
alfombra o superficie similar puede bloquea la ventilación, no se debe colocar
en libreros o gabinetes que impidan el flujo de aire por los orificios de
ventilación.
10. El equipo eléctrico deber ser situado fuera del alcance de fuentes de calor
como radiadores, registros de calor, estufas u otros aparatos (incluyendo
amplificadores) que producen calor.
11. El aparato eléctrico deberá ser connectado a una fuente de poder sólo del
tipo descrito en el instructivo de operación, o como se indique en el aparato.

3
NOM STATEMENT
12. Precaución debe ser tomada de tal manera que la tierra fisica y la polarización
del equipo no sea eliminada.
13. Los cables de la fuente de poder deben ser guiados de tal manera que
no sean pisados ni pellizcados por objetos colocados sobre o contra ellos,
poniendo particular atención a los contactos y receptáculos donde salen
del aparato.
14. El equipo eléctrico debe ser limpiado únicamente de acuerdo a las
recomendaciones del fabricante.
15. En caso de existir, una antena externa deberá ser localizada lejos de las
lineas de energia.
16. El cable de corriente deberá ser desconectado del cuando el equipo
no sea usado por un largo periodo de tiempo.
17. Cuidado debe ser tomado de tal manera que objectos liquidos
no sean derramados sobre la cubierta u orificios de ventilación.
18. Servicio por personal calificado deberá ser provisto cuando:
A: El cable de poder o el contacto ha sido dañado; u
B: Objectos han caído o líquido ha sido derramado dentro del aparato; o
C: El aparato ha sido expuesto a la lluvia; o
D: El aparato parece no operar normalmente o muestra un cambio
en su desempeño; o
E: El aparato ha sido tirado o su cubierta ha sido dañada.

4
IEEE 488 BUS EXTENDER AND IEEE 488 FIBER BUS EXTENDER
Contents
Chapter Page
1. Specifications ............................................................................................................5
1.1 IEEE 488 Bus Extender (IC095A) ..............................................................5
1.2 IEEE 488 Fiber Bus Extender (IC096A) ....................................................6
2. Introduction 7
2.1 Description ....................................................................................................7
2.2 Abbreviations ................................................................................................8
2.3 What’s Included ............................................................................................9
3. Configuration..........................................................................................................10
3.1 Configuring the IEEE 488 Bus Extender (IC095A) ................................10
3.1.1 Setting the Serial Baud Rate ..........................................................10
3.1.2 Serial Data Format Selection ..........................................................11
3.1.3 Serial Port Cabling ..........................................................................12
3.2 IEEE 488 Fiber Bus Extender Configuration (IC096A) ..........................12
3.2.1 Overview ..........................................................................................12
3.2.2 Installation and Maintainance ........................................................13
4. Operation ................................................................................................................10
4.1 Powering the System ..................................................................................14
4.2 Parallell Poll Response Time ....................................................................15
5. IEEE 488 Primer ....................................................................................................17
5.1 History..........................................................................................................17
5.2 General Structure ......................................................................................17
5.3 Send It to My Address ................................................................................20
5.4 Bus Management Lines ..............................................................................20
5.5 Handshake Lines ........................................................................................21
5.6 Data Lines....................................................................................................22
5.7 Multiline Commands..................................................................................22
5.8 More On Service Requests ........................................................................24
5.8.1 Serial Poll..........................................................................................25
5.8.2 Parallel Poll ......................................................................................25
6. Service Information ................................................................................................26
6.1 Theory of Operation ..................................................................................26
6.2 IEEE 488 Bus Extender Board (IC095A)..................................................27
6.3 IEEE 488 Fiber Bus Extender Board (IC096A)........................................28
6.4 Calling Black Box........................................................................................29
6.5 Shipping and Packaging ............................................................................29
Appendix Character Codes and IEEE Multiline Messages ......................................30

5
1. Specifications
1.1 IEEE 488 Bus Extender (IC095A)
IEEE 488-1978 — Implementation: Proprietary transparent control and
data transfers
Connector: Standard IEEE 488 connector with
metric studs
Serial Interface — EIA RS-422A: Balanced voltage on TxD and RxD
Connector: DB9 female
Character Set: Proprietary asynchronous bit serial
Baud Rate: Selectable 300, 600, 1200, 2400, 4800,
9600, 19,200, and 115,200
Data Format: Selectable 7 or 8 data bits; 1 stop bit;
odd parity
Max. Cable Length: 3280 feet (1000 meters)
Data Rates — Specifications apply to data transfers after addressing has
been established
Baud Rate Data Rate (bytes per second, average)
300 13
600 26
1200 53
2400 105
4800 204
9600 385
19,200 691
115,200 3400
Indicators — LEDs for IEEE Talk, Listen, SRQ, Error, and Power
Controls — Power switch (external), serial parameter switches
(internal)
CHAPTER 1: Specifications

6
IEEE 488 BUS EXTENDER AND IEEE 488 FIBER BUS EXTENDER
Temperature — 32 to 122°F (0 to 50°C)
Humidity — Up to 70% relative humidity
Power — 105- to 125-VAC or 210- to 250-VAC; 50-60 Hz, 10 VA max.
Size — 2.7"H x 5.5"W x 7.4"D (6.9 x 14 x 18.8 cm)
Weight —3.1 lb. (1.4 kg)
1.2 IEEE 488 Fiber Bus Extender (IC096A)
IEEE 488-1978 — Implementation: Proprietary transparent control and
data transfers
Connector: Standard IEEE 488 connector with
metric studs
Fiberoptic
Interface — Wavelength: 820 nanometers typical
Connectors: SMA-905 series female
Required Cable: Duplex 100-µm, 140-µm clad fiber
optic; 200-MHz-km bandwidth;
6 dB/km max. attenuation
Max. Cable Length: 3280 feet (1000 meters)
Data Rates — 3400 bytes per second typical
Indicators — LEDs for IEEE Talk, Listen, SRQ, Error, and Power
Temperature — 32 to 122°F (0 to 50°C)
Humidity — Up to 70% relative humidity
Controls — Power switch (external)
Power — 105- to 125-VAC or 210- to 250-VAC; 50-60 Hz, 10 VA max.
Size — 2.7"H x 5.5"W x 7.4"D (6.9 x 14 x 18.8 cm)
Weight — 3.6 lb. (1.6 kg)

7
CHAPTER 2: Introduction
2. Introduction
2.1 Description
The IEEE 488 Bus Extenders and IEEE 488 Fiber Bus Extenders help you control
IEEE 488 devices up to 4000 feet (1219.2 m) from the host computer. This
overcomes the IEEE 488’s specified limit of 6 feet (1.8 m) between any two
devices, with a maximum of 60 feet (18.3 m) total chained length. In addition,
the Extenders allow up to 30 devices to be on the bus—double the 15-device limit
imposed by the IEEE standard.
You’ll need two Extenders for bus extension. The bus connecting the host
computer, or controller, is the “local” bus. The bus to which control is extended
is the “remote” bus. An Extender is required on each bus for IEEE bus extension.
The IEEE 488 Bus Extender (IC095A) transmits RS-422 data between Extenders.
RS-422, a differential serial data format, provides high noise immunity and long
distances using low-cost twisted-pair wire.
The IEEE 488 Fiber Bus Extender (IC096A) communicates serially over duplex
fiberoptic cables. Fiberoptic transmission provides even better noise immunity, low
RFI emissions, and long distances.
Extender operation is completely transparent to the system. The controller can
access both local and remote devices just as it could without the Extender, with the
exception of Parallel Poll (see “Parallel Poll Response Times” in Chapter 4).

8
IEEE 488 BUS EXTENDER AND IEEE 488 FIBER BUS EXTENDER
2.2 Abbreviations
The following IEEE 488 abbreviations are used throughout this manual.
addr n IEEE bus address “n”
ATN Attention line
CA Controller Active
CO Controller
CR Carriage Return
data Data String
DCL Device Clear
GET Group Execute Trigger
GTL Go To Local
LA Listener Active
LAG Listen Address Group
LF Line Feed
LLO Local Lock Out
MLA My Listen Address
MTA My Talk Address
PE Peripheral
PPC Parallel Poll Configure
PPU Parallel Poll Unconfigure
SC System Controller
SDC Selected Device Clear
SPD Serial Poll Disable
SPE Serial Poll Enable
SRQ Service Request
TA Talker Active
TAD Talker Address
TCT Take Control
term Terminator
UNL Unlisten
UNT Untalk
* Unasserted

9
2.3 What’s Included
The Extenders are carefully inspected prior to shipment. Before you start using
your Extender, however, carefully inspect it for any obvious signs of physical
damage which may have occurred during shipping. Immediately report any
damage found. Remember to retain all shipping materials in case shipping
the Extender back to the factory becomes necessary.
Every Extender is shipped with a power supply and this user guide.
WARNING!
The Extender requires a regulated external power supply with a maximum
output of 5.25 volts. Using voltages above this level will result in damage
to the interface. Only use power supplies provided by Black Box.
CHAPTER 2: Introduction

10
IEEE 488 BUS EXTENDER AND IEEE 488 FIBER BUS EXTENDER
3. Configuration and Installation
3.1 Configuring and Installing the IEEE 488 Bus Extender (IC095A)
This section describes the configuration necessary for the RS-422 IEEE 488 Bus
Extenders. If you are using the fiberoptic extenders (IC096A), refer to Section 3.2.
Two IEEE 488 Bus Extenders are required for bus extension, with one connected
directly to the local IEEE bus, and the other connected to the remote IEEE bus.
Both local and remote Extenders are identical. At power-up, each Extender
monitors the Attention (ATN) and Remote Enable (REN) lines. The Error LED
on each Extender will blink, indicating that ATN or REN has not yet been detected
and that communication with the other Extender has not yet been established.
The first Extender to detect either of these lines asserted declares itself the local
Extender and commands the other Extender to declare itself the remote Extender.
The Error LEDs will now stop blinking. From this moment on, the local Extender
will monitor all local bus activity and transmit this activity to the remote Extender.
All activity detected by the remote Extender is also communicated back to the local
Extender.
3.1.1 S ETTING THE S ERIAL B AUD R ATE
The Extender is shipped with the serial baud rate set to 115.2 Kbps. For most
applications, this is the most efficient operating rate. However, if the Extenders will
be located at extreme distances from each other, baud rates other than 115.2 Kbps
can be selected. Selectable baud rates include 115.2 Kbps, 19.2 Kbps, 9600 bps,
4800 bps, 2400 bps, 1200 bps, 600 bps, and 300 bps. Both Extenders must be set
to the same baud rate for proper operation.
To modify the baud rate, disconnect the power supply from the AC line and
from the interface. Disconnect any IEEE or serial cables prior to disassembly.
WARNING!
Never open the Extender’s case while it is connected to the AC line.
Doing so may result in equipment failure, personal injury, or death.

11
CHAPTER 3: Configuration and Installation
Remove the screws located in each corner of the rear panel. Hold the case firmly
and pull the rear panel outward, noting the slot location of the main circuit board.
Set the DIP switches for the baud rate you want (use Figure 3-1 as a guide) and
reassemble the unit. Slide the main circuit board into the previously noted slot
and finish reassembly by re-tightening the screws.
Figure 3-1. Baud Rate Selection.
3.1.2 S ERIAL D ATA F ORMAT S ELECTION
The Extender is configurable for two data formats. The first format, the factory
default, is 8 data bits, 1 stop bit with odd parity. The number of data bits trans-
mitted can be set to 7 by setting S102 switch 4 to the closed position. Even
though the seven-bit format is chosen, binary data can still be transferred over
the Extenders. There will, however, be a slight degradation in data-transfer speeds
with this format.
Figure 3-2. Data Format Selection.

12
IEEE 488 BUS EXTENDER AND IEEE 488 FIBER BUS EXTENDER
3.1.3 I NSTALLING
S ERIAL P ORT C ABLING
The Extender is designed to use an RS-422 transmission medium, which prescribes
differential receivers for high noise immunity. To ensure signal integrity, only use
shielded cable for the serial-port connections. If you are not using a cable provided
by Black Box, listed below are the appropriate connections for proper operation.
3.2 Configuring and Installing the IEEE 488 Fiber Bus Extender (IC096A)
3.2.1 O VERVIEW
This section describes the configuration necessary for the fiberoptic IEEE 488
Fiber Bus Extenders. If you are using the RS-422 extenders (IC095A), refer to
Section 3.1.
Two Extenders are required for bus extension, with one connected directly
to the local IEEE bus, and the other connected to the remote IEEE bus.
Both local and remote Extenders are identical. At power-up, each Extender
monitors the Attention (ATN) and Remote Enable (REN) lines. The Error LED
on each Extender will blink, indicating that ATN or REN has not yet been detected
and that communication with the other Extender has not yet been established.
The first Extender to detect either of these lines asserted declares itself the local
Extender and commands the other Extender to declare itself the remote Extender.
The Error LEDs will now stop blinking. From this moment on, the local Extender
will monitor all local bus activity and transmit this activity to the remote Extender.
All activity detected by the remote Extender is also communicated back to the
local Extender.
WARNING!
There are no user-serviceable parts or user-selectable parameters inside
the Extender’s case. Refer all servicing to qualified repair personnel. Refer
to Section 6.4 for additional information on malfunctioning equipment.

13
CHAPTER 3: Configuration and Installation
3.2.2 I NSTALLING AND
M AINTAINING F IBEROPTIC C ONNECTIONS
The Extender requires duplex fiberoptic cabling. Most cable manufacturers
mark the two connectors at each end of the duplex cable with a “T” and an “R”
to distinguish which to connect to the transmitter (T) and which to connect to
the receiver (R). Connect the fiberoptic cables as shown below. The Transmitter
of #1 is connected to the receiver of #2 and vice versa.
Follow these guidelines for taking care of your Extender.
1. Treat the fiberoptic transmitter, receiver, and cabling ends gently. Good
system performance requires clean port optics and cable ferrules to avoid
obstructing the optical path.
2. Compressed air is often all that’s needed to remove dirt particles from the
optic transmitters and receivers. Standard lens-cleaning tissues or cotton
swabs soaked with methanol or freon also work well for cleaning cable
ferrules. Be careful not to splash methanol or freon on case parts.
3. When the Extender is not in use, replace the Extender’s optical transmitter
and receiver protection caps. Make sure cable ferrule protection caps are
also replaced.
4. When pulling optical cable through conduits of walls, never use the
connectors as a link to the pulling lead. Make sure that the cable is loose
in the conduit after installation. If the cable is pulled tight on a corner,
transmission loss may be increased significantly.
5. When seating connectors in the transmitter and receiver, you might have
to turn the connector a little to achieve satisfactory transmission.
Extender #1 Extender #2

14
IEEE 488 BUS EXTENDER AND IEEE 488 FIBER BUS EXTENDER
4. Operation
4.1 Powering the System
After configuring the Extenders and attaching the serial port or fiberoptic
cabling, plug the power-supply connector into the rear jack on the interface.
CAUTION
Always connect the power supply to the Extender first, then to the AC
line power. Connecting it to the power first may result in damage to the
Extender. Only a supply with regulated +5-volt output should be used.
WARNING
The power supply provided with the interface is intended for indoor use
only. Using it outdoors could result in equipment failure, personal
injury, or death.
After connecting the power supply to the Extender, plug the power supply into the
AC line power. Place the rear-panel power switch in the ON [1] position. All front-
panel indicators should light for approximately one second while the Extender
performs an internal ROM and RAM self-check. At the end of the power-on
sequence, the ERROR LED should continue to blink, indicating that commun-
ication with another Extender has not been established. Now repeat the above
procedure with the second Extender. All LEDs should function the same as with
the first Extender. If any of the following LED conditions exist after power-on,
a failure has occurred.
SYMPTOM FAILURE
All lights remain on. ROM test has failed.
All lights blink continually. RAM test has failed.
No LEDs blink. Power supply has failed.
If any of the symptoms shown occur, cycle the power switch on the Extender
to be sure of the problem. If the problem is unresolved, refer to Chapter 6.
WARNING
The Extender makes its earth-ground connection through the IEEE
interface cable. Each Extender must be connected to at least one IEEE
device which is earth-ground referred. Failure to do so may allow
dangerous voltages to build up. This could result in damage to the
interface, personal injury, or death.

15
CHAPTER 4: Operation
If the Extender seems to be operating properly, turn off the Extender’s power
switch and connect the other IEEE devices to each of the Extender’s IEEE ports.
Connect the local Extender to the remote Extender via the serial or fiberoptic
cable. Apply power to all devices in the system. If the Extender’s ERROR LED
continues to blink after the power-on sequence, this indicates one of two possible
conditions: either the system controller has not yet asserted the Attention line, or
communication with the mating Extender has not yet been established. Be sure
both Extenders are powered on, the cabling has been installed, and the controller
has asserted Attention before assuming there is a problem.
Once all IEEE devices have been connected and powered on, the Extender will
allow the system controller to command up to 13 IEEE devices on its local bus (in
addition to the controller itself and the local Extender), and up to 14 IEEE devices
on the remote bus (in addition to the remote Extender). The Extenders have
no address of their own, and therefore will operate completely transparent to the
system (with the exception of parallel poll—see below). Be careful not to have
two IEEE devices with the same address connected to either remote or local buses.
If you do, the bus will “lock up” when one of the devices is accessed.
4.2 Parallel Poll Response Times
The Parallel Poll function is the only extended bus transaction which is not
completely transparent to your system. This is because the speed at which data is
transferred serially is slower than the IEEE specification for Parallel Poll response.
Consequently, it is necessary for the controller to perform two Parallel Polls.
When the local Extender detects the parallel poll, it outputs the most recent
Parallel Poll information to the controller on the local bus. This data should be
discarded by the controller because it is not current. After receiving a Parallel Poll,
the local Extender commands the remote Extender to perform a Parallel Poll, and
returns the remote Parallel Poll data byte to the local Extender. The bus controller
should now perform another Parallel Poll and use this data as the valid Parallel
Poll byte. The table on the next page describes the minimum times the controller
should wait between consecutive Parallel Polls in order to assure valid data on the
second poll.

16
IEEE 488 BUS EXTENDER AND IEEE 488 FIBER BUS EXTENDER
Table 4-1. Extender Parallel Poll Response Times
The minimum time the controller should wait with the IEEE 488 Fiber Bus
Extender between consecutive Parallel Polls is 1 millisecond.

17
5. IEEE 488 Primer
5.1 History
The IEEE 488 bus is an instrumentation communication bus adopted by the
Institute of Electrical and Electronic Engineers in 1975 and revised in 1978.
The IEEE 488 Bus Extender and the IEEE 488 Fiber Bus Extender conform
to this most recent revision designated IEEE 488-1978.
Prior to the adoption of this standard, most instrumentation manufacturers
offered their own versions of computer interfaces. This placed the burden of
system hardware design on the end user. If his application required the products
of several different manufacturers, then he might need to design several different
hardware and software interfaces. The popularity of the IEEE 488 interface
(sometimes called the General Purpose Interface Bus or GPIB) is due to the
total specification of the electrical and mechanical interface as well as the data
transfer and control protocols. The use of the IEEE 488 standard has moved the
responsibility of the user from design of the interface to design of the high-level
software that is specific to the measurement application.
5.2 General Structure
The main purpose of the GPIB is to transfer information between two or more
devices. A device can either be an instrument or a computer. Before any
information transfer can take place, it’s first necessary to specify which will do the
talking (send data) and which devices will be allowed to listen (receive data). The
decision of who will talk and who will listen usually falls on the System Controller,
which is, at power-on, the Active Controller.
The System Controller is similar to a committee chairman. On a well-run
committee, only one person may speak at a time and the chairman is responsible
for recognizing members and allowing them to have their say. On the bus, the
device which is recognized to speak is the Active Talker. There can only be one
Talker at a time if the information transferred is to be clearly understood by all.
The act of “giving the floor” to that device is called Addressing to Talk. If the
committee chairman cannot attend the meeting, or if other matters require his
attention, he can appoint an acting chairman to take control of the proceedings.
For the GPIB, this device becomes the Active Controller.
At a committee meeting, everyone present usually listens. This is not the case with
the GPIB. The Active Controller selects which devices will listen and commands all
other devices to ignore what is being transmitted. A device is instructed to listen by
CHAPTER 5: IEEE 488 Primer