Measurement Isolator488 User Manual

Isolator488

IEEE 488 Bus Isolator

USER’S MANUAL

IOtech, Inc. • 25971 Cannon Road • Cleveland, Ohio 44146 • [phone]

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Refer all service to qualified personnel. This caution symbol warns of possible personal injury or equipment damage
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Isolator488

Instruction Manual

Part No. Isolator488-901

Revision 1.2

December 1991

IOtech, Inc.



25971 Cannon Road  Cleveland, Ohio 44146  [phone]

IMPORTANT!

READ THIS BEFORE INSTALLATION!

WARNING

The enclosure of the Isolator488 Bus Isolator is
internally connected to earth ground through the
power cord. However, the shield of the IEEE 488
cables attached to the Isolator488 and signal ground
pins may be at a high voltage with respect to earth
ground. Be sure to remove power from all devices in
your system before handling IEEE 488 cables
connected to the Isolator488. Failure to follow this
warning may result in personal injury or death.

IOtech, Inc. • 25971 Cannon Road • Cleveland, Ohio 44146 • [phone]

Table of Contents

Section 1 INTRODUCTION Page

1.1 General Description 1.1

1.2 Available Accessories 1.1

1.3 Specifications 1.2

1.4 Abbreviations 1.3

Section 2 GETTING STARTED Page

2.1 Inspection 2.1

2.2 Configuration 2.1

2.3 Modifications 2.4

2.4 Line Voltage Selection 2.7

2.5 Hardware Installations 2.9

2.6 Operation 2.10

2.6.1 BusLoading 2.11

2.6.2 Cabling Length 2.11

2.6.3 Signal Line Direction 2.12

2.6.4 Parallel Polling 2.13

2.6.5 Passing Control 2.13

Section 3 IEEE 488 Primer Page

3.1 History 3.1

3.2 General Structure 3.1

3.3 Send It To My Address 3.5

3.4 Bus Management Lines 3.5

3.4. Attention (ATN) 3.5

3.4.2 Interface Clear (IFC) 3.6

3.4.3 Remote Enable (REN) 3.6

3.4.4 End Or Identify (EOI) 3.6

3.4. Service Request (SRQ) 3.6

3.5 Handshake Lines 3.7

3.5.1 Data Valid (DAV) 3.7

3.5.2 Not Ready For Data (NRFD) 3.7

3.5.3 Not Data Accepted (NDAC) 3.7

3.6 Data Lines 3.8

3.7 Multiline Commands 3.8

Section 3 (cont.) Page

3.7.1 Go To Local (GTL) 3.8

3.7.2 Listen Address Group (LAG) 3.9

3.7.3 Unlisten (UNL) 3.9

3.7.4 Talk Address Group (TAG) 3.9

3.7.5 Untalk (UNT) 3.9

3.7.6 Local Lockout (LLO) 3.9

3.7.7 Device Clear (DCL) 3.9

3.7.8 Selected Device Clear (SDC) 3.10

3.7.9 Serial Poll Disable (SPD) 3.10

3.7.10 Serial Poll Enable (SPE) 3.10

3.7.11 Group Execute Trigger (GET) 3.10

3.7.12 Take Control (TCT) 3.10

3.7.13 Secondary Command Group (SCG) 3.10

3.7.14 Parallel Poll Configure (PPC) 3.11

3.7.15 Parallel Poll Unconfigure (PPU) 3.11

3.8 More On Service Requests 3.11

3.8.1 Serial Poll 3.12

3.8.2 Parallel Poll 3.12

Section 4 SERVICE INFORMATION Page

4.1 Factory Service 4.1

Appendix A

Character Codes and IEEE Multiline Messages

Section 1 Introduction

Introduction

1.1 GENERAL DESCRIPTION

The Isolator488 increases the number of IEEE instruments and devices allowable
on the bus from 15, including the controller, to 28 while also providing optical
isolation between the system controller and devices on the isolated bus. Since the
Isolator488 does not occupy a bus address, its operation is entirely transparent to the
IEEE controller. The IEEE standard defines 31 valid primary bus addresses.
Therefore, no special software or bank switching is necessary to access the additional
devices allowed by the Isolator488. The Isolator488 and has no effect on bus data
transfer rates.

Two IEEE ports are provided. One connects directly to the controller's IEEE bus,
the other to an additional 14 instruments, printers, plotters and specialized peripherals
which may need to be optically isolated from the system controller.

1.2 AVAILABLE ACCESSORIES

Additional accessories that can be ordered for the Isolator488 include:

123-0900
CA-7-1
CA-7-2
CA-7-3
CA-7-4
CN-20
CN-21
CN-22

CN-23

Instruction Manual

1.5 foot IEEE 488 cable
6 foot IEEE 488 cable
6 foot Shielded IEEE 488 cable
Reverse entry 6 foot IEEE 488 cable
Right Angle IEEE 488 adapter, male and female
IEEE 488 connector Extender, male and female
IEEE 488 multi-tap bus strip, four female
connectors wired in parallel.
IEEE 488 panel mount feed-through connector,
male and female

1.1

Section 1 Introduction

1.3 SPECIFICATIONS

PROPAGATION DELAYS:

Local to Remote Talker

Data Lines 85 nS typ., 120 nS Max.
Command Lines 90 nS typ., 125 nS Max.

Remote to Local Talker

/ATN to Local Data 355 nS typ., 475 nS Max.
/ATN to Local DAV 155 nS typ., 2075 nS Max.
Data Lines 85 nS typ., 120 nS Max.
Command Lines 90 nS typ., 125 nS Max.
Parallel Poll Response 140 nS typ., 205 nS Max.

SIGNAL LINE DIRECTIONS:

Data Lines:

DIO1 - DIO7 Bidirectional

Handshake Lines:

DAV, NRFD, NDAC Bidirectional

Command Lines:

SRQ, ATN, REN, IFC To Local Bus
ATN To Remote Bus
EOI Bidirectional

CONNECTORS: Two IEEE 488 connectors with metric studs
INDICATORS: LED for Power
POWER: 105-125V or 210-250V,50, 60 Hz; 20 VA MAX.
ENVIRONMENT: 0 to 50 °C; 0 to 70% RH
DIMENSIONS: 425 mm deep x 45 mm wide x 208 mm high.

(16.75 "x 1.75 "x 8.20 ")
WEIGHT: 2.1 kg (4.6 lbs)
CONTROLS: Power switch
SUPPLIED ACCESSORIES: Power cable and manual
ISOLATION: IEEE 488 common on Controller Bus to IEEE 488

common on Instrument Bus:

1600 volts peak maximum @ sea level to 10,000 ft.

0 - 70° C, and 0 - 80% RH non-condensing OR

5

500 Vac maximum, 10

Specifications are subject to change without notice.

V-Hz

1.2

Section 1 Introduction

1.4 Abbreviations

The following IEEE 488 abbreviations are used throughout this manual.

addr n IEEE bus address "n"
ATN Attention line
CA Controller Active
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
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

1.3

Section 2 Getting Started

GETTING STARTED

2.1 Inspection

The Isolator488 was carefully inspected, mechanically and electrically, prior to
shipment. When you receive the interface, carefully unpack all items from the
shipping carton and check for any obvious signs of physical damage which may have
occurred during shipment. Report any damage to the shipping agent immediately.
Remember to retain all shipping materials in the event that shipment back to the
factory becomes necessary.

Every Isolator488 is shipped with the following....

•

Isolator488

•

123-0900

•

123-0800

2.2 Configuration

Before using the Isolator488, you should be aware of the connections
between the IEEE digital commons, the shield lines on each bus, and earth ground.
The following information is provided so that you can determine if the factory
configuration is appropriate for your application or if some changes need to be
made prior to use.

The following is a list of terms and their definitions as used in this manual:

Isolation The ability of the Isolator488 to break the electrical

connection between the shields and digital commons
of its IEEE 488 ports while allowing the transfer of
data.

IEEE Bus Isolator
Instruction Manual
Accessory Kit ( includes power cable,
fuse, and rack mounting hardware)

2.1

Section 2 Getting Started

Earth Ground The Ground terminal on the AC power cable. This is

internally connected to the chassis of the Isolator488.

Controller Port The IEE 488 port labeled CONTROLLER on the rear

panel of the Isolator488. The system controller
must be connected to this port. Instruments may also be
connected to this port, but instruments placed in the
CONTROLLER port will not be isolated from the
system controller.

Instrument Port The IEEE488 port labeled INSTRUMENTS on the

rear panel of the Isolator488. Instruments may be
connected to this port. Instruments connected to the
Instrument Port may be isolated from devices on the
Controller Port depending on the internal configuration
of the Isolator 488.

Controller Common The logic common connection on the Controller Port.

Pins 18, 19, 20, 21,22, 23, and 24 of the Controller
Port are all connected to Controller Common.

Instrument Common The logic common connection on the Instrument Port.

Pins 18, 19, 20, 21, 22, 23, and 24 of the Controller

Port are all connected to Instrument Common.
Controller Shield The Shield connection (Pin 12) on the Controller Port.
Instrument Shield The Shield connection (Pin 12) on the Instrument Port

The factory configuration of the Isolator488 is as follows:

2.2