Pickering SYSTEM 10 User manual

Page (1)
RS232/IEEE-488.2 INTERFACE 10-921
pickering
Issue 4.1 July 2019
User Manual
GPIB RS232/IEEE-488.2 Interface
(Model No. 10-921-001)
pickeringtest.com pickering
SYSTEM 10/20

Page (II) RS232/IEEE-488.2 INTERFACE 10-921
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Page (II) REED RELAY MODULE 40-110/115/120/125
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© COPYRIGHT (2019) PICKERING INTERFACES. ALL RIGHTS RESERVED.
No part of this publication may be reproduced, transmitted, transcribed, translated or stored in any form, or by
any means without the written permission of Pickering Interfaces.
Technical details contained within this publication are subject to change without notice.
ISO 9001
Reg No. FM38792

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RS232/IEEE-488.2 INTERFACE 10-921
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Page (III)
REED RELAY MODULE 40-110/115/120/125
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TECHNICAL SUPPORT
For Technical Support please contact Pickering Interfaces either by phone, the website or via e-mail.
WARRANTY
All products manufactured by Pickering Interfaces are warranted against defective materials and workmanship for a period of
three years, excluding programmable power supplies, from the date of delivery to the original purchaser. Any product found to be
defective within this period will, at the discretion of Pickering Interfaces be repaired or replaced.
Products serviced and repaired outside of the warranty period are warranted for ninety days.
Extended warranty and service are available. Please contact Pickering Interfaces by phone, the website or via e-mail.
ENVIRONMENTAL POLICY
Pickering Interfaces operates under an environmental management system similar to ISO 14001.
Pickering Interfaces strives to full all relevant environmental laws and regulations and reduce wastes and releases to the
environment. Pickering Interfaces aims to design and operate products in a way that protects the environment and the health and
safety of its employees, customers and the public. Pickering Interfaces endeavours to develop and manufacture products that can
be produced, distributed, used and recycled, or disposed of, in a safe and environmentally friendly manner.
Worldwide Technical Support and Product Information
pickeringtest.com
Germany
Tel: [phone]
E-mail: [email protected]
Sweden
Tel: [phone]
E-mail: [email protected]
USA
Tel: (West) [phone]
Tel: (East) [phone]
E-mail: [email protected]
Czech Republic
Tel: [phone]
E-mail: [email protected]
France
Tel [phone]
E-mail [email protected]
Pickering Interfaces Headquarters
Stephenson Road Clacton-on-Sea CO15 4NL United Kingdom
Tel: [phone]
E-Mail: [email protected]
China
Tel: [phone]
E-mail: [email protected]

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Page (IV) REED RELAY MODULE 40-110/115/120/125
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MEANING / DESCRIPTION SYMBOL
PROTECTIVE EARTH (GROUND)
To identify any terminal which is intended for connection to an external conductor for
protection against electric shock in case of a fault, or the terminal of a protective earth
(ground) electrode.
DANGEROUS VOLTAGE
To indicate hazards arising from dangerous voltages.
WARNING / CAUTION
An appropriate safety instruction should be followed or caution to a potential hazard
exists.
Refer to the relevant instructions detailed within the product manual.
HEAVY
If this product is heavy reference should be made to the safety instructions for
provisions of lifting and moving.
STATIC SENSITIVE
To indicate that static sensitive devices are present and handling precautions should
be followed.
!
kg
SAFETY SYMBOLS
PRODUCT SAFETY
The following safety symbols may be used on the product and throughout the product documentation.

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RS232/IEEE-488.2 INTERFACE 10-921
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CONTENTS
Copyright Statement ...................................................................II
Technical Support and Warranty................................................III
Product Safety .............................................................................IV
Contents (this page)....................................................................V
Warnings and Cautions ..............................................................VII
Section 1
Technical Specication...............................................................1.1
Section 2
Getting Started.............................................................................2.1
Section 3
Programming............................................................................... 3.1
Section 4
System 10/20 Commands ...........................................................4.1
Section 5
IEEE-488.2 Command Structure.................................................5.1
Section 6
IEEE-488.1 Interface Details .......................................................6.1
Section 7
RS-232 Interface Details..............................................................7.1
Section 8
Trouble Shooting.........................................................................8.1
Section 9
Maintenance Information............................................................9.1
Appendix A Self-Test Failure Table........................................A.1
Appendix B Error Message Table ..........................................B.1
Appendix C IEEE-488.2 Status Registers..............................C.1
Appendix D Command Execution Times ..............................D.1
Please use the hyperlinked text to navigate to the page required

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Page (VII)
RS232/IEEE-488.2 INTERFACE 10-921
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Page (VII)
GENERAL PURPOSE REED RELAY MODULE 10-110/115/120/125
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WARNINGS AND CAUTIONS
WARNING - HAZARDOUS ENVIRONMENTS SYMBOL
This product is not specically designed for use in hazardous environments, for example in explosive
atmospheres. If the product is to be used in hazardous environments we recommend that the user
ensures suitable protective measures are taken.
!
WARNING - DANGER OF ELECTRIC SHOCK SYMBOL
This module may contain hazardous voltages. Before removing the module from the rack remove all
supplies and disconnect user I/O signals.
Unused slots in the System 10/20 chassis are populated with blanking plates to prevent access
to user I/O signals that may be present. Blanking panels are available to order from Pickering in a
variety of slot widths. If the product is not used in this manner for example by using an extender card
then additional care must be taken to avoid contact with exposed signals.
CAUTION - HANDLING OF ELECTROSTATIC-SENSITIVE DEVICES SYMBOL
Certain semiconductor devices used in this equipment are liable to damage due to static voltage.
Observe the following precautions when handling these devices in their unterminated state, or
sub-assemblies containing these devices:
1. Persons removing sub-assemblies from equipment using these devices must be earthed by a
wrist strap and a resistor at the point provided on the equipment.
2. Soldering irons used during the repair operations must be low voltage types with earthed tips and
isolated from the mains voltage by a double insulated transformer.
3. Outer clothing worn must be unable to generate static charges.
4. Printed Circuit Boards (PCBs) tted with these devices must be stored and transported in
anti-static bags.
CAUTION - PRODUCT DOCUMENTATION SYMBOL
Suitably qualied & trained users should ensure that the accompanying documentation is fully read
and understood before attempting to install or operate the product.
!
SAFETY INSTRUCTIONS
SAFETY INSTRUCTIONS
All cleaning and servicing requires the equipment to be isolated and disconnected from the power source and user I/O
signals (refer to the Maintenance Section).
• Appropriate manual handling procedures should be followed as dictated by the weight of the individual module or
the combined weight of the modules & chassis.
• Should a fault occur with the module or chassis, immediately isolate and disconnect the incoming power to the
chassis and the user I/O signals.
• Ensure the equipment is installed, operated and maintained by trained and authorised personnel.

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Page 1.1
RS232/IEEE-488.2 INTERFACE 10-921
pickering SECTION 1 - TECHNICAL SPECIFICATION
SECTION 1 - TECHNICAL SPECIFICATION
pickeringtest.com
GPIB RS-232/IEEE-488.2/Ethernet Interface 10-920A/921/922
ISSUE 5.3 SEP 2018
• IEEE-488, RS-232 & Ethernet Interface
• 32 Bit Microprocessor For Fast Response
• Fully IEEE-488.2 Compatible, So Providing a
Familiar Software Interface
• Supports ALL System 10/20 Modules and
Configurations
• Special Support for Large Matrix & Multiplexer
Systems
• Extensive Error Handling and Reporting in
English Language or Numeric Format
• Full Self Test Diagnosis Support
• Comprehensive & Easy To Use Instruction Set
• Large I/O Buffers Increase Throughput
The 10-921 IEEE-488.2/RS-232 and 10-922 IEEE-488/Ethernet
Interface Modules provides a versatile means of communicating
with a Pickering Interfaces’ Switching System. The instruction
set has been designed to ease integration of System 10/20 into
your Test or Data Acquisition environment. The use of a 32 bit
microprocessor ensures maximum response and throughput.
The 10-921 interface module provides any System 10/20 Switching
System with a full RS-232 and IEEE-488.2 interface. The 10-921
interface features powerful but easy to use instructions, which hide
many of the intricacies required when operating complex switching
systems, especially large multiplexers (scanners) and matrices.
IEEE-488.2 Compatible
The 10-921 Intelligent Interface is totally compatible with the IEEE-
488.2 (1987) standard, both the IEEE-488 and RS-232-C interfaces
follow IEEE-488.2 Protocols.
This software standard is the basis for SCPI and is much used in
VXI based instrumentation. For further information on the IEEE-
488.2 standard please refer to the 10-920 data sheet or you may
request a programming manual from Pickering.
• RS-232: The serial interface allows System 10 and 20 units to
be controlled from any standard PC, with a wide range of baud
rates plus a choice of software or hardware handshaking.
• IEEE-488 (GPIB): High speed IEEE-488.2 interface. The
10-921 is a faster version of the popular 10-920A interface
module, the two modules are compatible.
• Ethernet: Model 10-922 has an Ethernet (10BaseT) port that
supports standard protocols such as TCP/IP and SMNP.
Fast and Easy Programming
The 10-921 uses a 32 bit microprocessor (Motorola 68332) to
give maximum operating throughput. All programming is done in
ASCII using English-like instructions with support for most number
formats, all instructions follow exactly the same syntax. Incoming
instructions are placed into an input buffer, therefore a large block
of instructions may be sent to the interface which can then be left
to execute, thus leaving the control computer free to carry out other
tasks. A large output buffer simplies status and error reporting.
Full support is given to application program debug using the VIEW?
and REPORT? instructions, any incoming instruction which causes
offence (due to incorrect or invalid instructions or arguments) can
be read back together with a description of the problem. In addition
self testing and detailed fault diagnosis simplify test system debug
and maintenance.
*SAV/*RCL Stored Status Support
The 10-920A/921/922 has 256 internal registers which can be
used for storing the state of the complete switching system into
nonvolatile ash memory. These can be later recalled, using the
*RCL instruction, thus saving the user having to send a large
number of switch programming commands.

Page 1.2 RS232/IEEE-488.2 INTERFACE 10-921
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SECTION 1 - TECHNICAL SPECIFICATION
RS-232/IEEE-488.2/Ethernet Interface – 10-920A/921/922
pickeringtest.com
Specifications
IEEE-488.2 STANDARD INSTRUCTION SET
SynchronisationStored Settings
*RCL *SAV *OPC *OPC? *WAI
Internal Operations
*IDN? *RST TST?
Status Reporting
*CLS
*ESE *ESE? *ESR? *SRE *SRE? *STB?
SWITCHING INSTRUCTION SET
a
x
y
a
x
y
ErrorsTime StatusSwitch/Digital Output MatrixClear Digital Input
Learn
*LRN?
Macros
*DMC *EMC *EMC *GMC? *LMC? *PMC
Future Enhancements
Multiplexer
ERRNO?
REPORT?RESET ARESET CLOSE OPEN WRITE MCLOSE MOPEN DELAY VIEW? TYPE? READ? CHAN
DIAGNOSTIC?
a a a
b b w
a
a
bc
e
aa
c
a
t
aa
b
a
mm
m
m
10-920A/921/922 Instruction Tree
IEEE-488.2 Common Instructions
*CLS Clear Status Command.
*ESE m Sets the selected bits in the SESE Register.
*ESE? Event Status Enable Query.
*ESR? Event Status Register Query.
*IDN? Identication Query.
*OPC Operation Complete Command.
*OPC? Operation Complete Query.
*RCL r
Restore the state of all modules to that stored in memory r.
*RST Device Reset command
*SAV r Save the current state of all modules to memory r.
*SRE m Sets the selected bits in the SRE Register.
*SRE? Status Register Enable Query.
*STB? Status Byte Query.
*TST? Self Test Query.
*WAI Wait-to-Continue Command
If the information here is of insufcient detail Pickering Interfaces can, upon request,
send you a 50 page programming manual. It is also available at our web site.
System 10 Device Specific Instructions
ARESET a Addressed Reset, clear module a.
CHAN a,c Close channel con scanner a.
CLOSE a,b Close switch bon module a.
DELAY t Delay of tmilliseconds.
DIAGNOSTIC? Returns full self-test fault diagnosis, if any.
ERRNO? Returns an error value in range “0” - “255”.
MCLOSE a,x,y Close switch at coordinates x,y on module a.
MOPEN a,x,y Open switch at coordinates x,y on module a.
OPEN a,b Open switch bon module a.
READ a Read input word from module a.
REPORT? Returns error string describing the last error.
RESET
Reset all modules to clear state (as at power on).
TYPE? a Return type and size of module a.
VIEW? [a,b] View status of whole system or module.
WRITE a,w Write word wto module a.
System 10/20 modules may be programmed completely using just the device
specic instructions, i.e. the IEEE-488.2 instructions can, if wished, be totally
ignored with little loss of functionality.
RS-232 Interface Specifications
• Connector Type is Standard 9-pin D-Type Socket (on ying lead).
• Input/Output Buffer Max Transfer Rate = 2kByte/Sec.
• Input/Output Buffer Size = 1kByte.
• RS-232-C Interface Functions: RxD, TxD, CTS, RTS plus software handshake.
• Baud Rates:
1200, 2400, 4800, 9600, 19200, 38400 & 57600.
IEEE-488 Interface Specifications
• Connector Type is Standard 24-pin GPIB type.
• Input/Output Buffer Burst Transfer Rate = 50kByte/Sec.
• Input/Output Buffer Size = 1kByte.
• IEEE-488.1 Interface Functions: SH1, AH1 T6, L4, SR1, RL0, PP0, DC1, DT0,
C0, E2.
• Compatible with Slower 10-920A Module.
• Fully Compatible with Original IEEE-488 (1978) Standard.
Instruction Execution Times
The average instruction execution time is around 5ms, this varies from <1ms up to
>100ms depending upon instruction type and system complexity (Note: *TST?
Self Test Command may take up to 1 minute for large matrix systems).
Typical execution times are:
CHAN a,c 2ms CLOSE a,b 5ms
MCLOSE a,x,y 5ms READ? 5ms
VIEW? a <1ms WRITE a,w 2ms
Example Instructions
CHAN 6,75 Close channel 75 on multiplexer with address 6.
CLOSE 5,2 Close switch 2 on module with address 5.
MOPEN 2,12,98 Open matrix crosspoint at x=12, y=98 on matrix with
address 2.
10-921 Front Panel has the following on it:
Indicators for Power On, System Active, Self-Test Active, Self-Test Error, RS-232
Active and IEEE-488 Active. In addition a recessed switch will initiate self test and
system exercise.
Mechanical Characteristics
All modules conform to the 3U height (128mm) Eurocard standard and are 160mm deep.
Panel width is 1.2 Inches.

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RS232/IEEE-488.2 INTERFACE 10-921
pickering SECTION 1 - TECHNICAL SPECIFICATION
RS-232/IEEE-488.2/Ethernet Interface – 10-920A/921/922
pickeringtest.com
Ordering Information
© Copyright (2019) Pickering Interfaces. All Rights Reserved Pickering Interfaces maintains a commitment to continuous product development, consequently we reserve the right to vary from the description given in this data sheet.
Product Order Codes
System 10 RS232/IEEE-488.2 Interface
System 10/20 RS232/IEEE-488.2 Interface
System 10/20 Ethernet Interface
10-920A-001
10-921-001
10-922-101
Product Customization
Pickering System 10 modules are designed and manufactured
on our own exible manufacturing lines, giving complete product
control and enabling simple customization to meet very specic
requirements.
Customization can include:
• Different performance specications
All customized products are given a unique part number, fully
documented and may be ordered at any time in the future. Please
contact your local sales ofce to discuss.
Operating/Storage Conditions
Operating Conditions
Operating Temperature:
Humidity:
Altitude:
0°C to +55°C
Up to 95% non-condensing
5000m
Storage and Transport Conditions
Storage Temperature:
Humidity:
Altitude:
-20°C to +75°C
Up to 95% non-condensing
15000m
Safety & CE Compliance
All modules are fully CE compliant and meet applicable EU
directives: Low-voltage safety EN61010-1:2010, EMC Immunity
EN61326-1:2013, Emissions EN55011:2009+A1:2010.

Page 1.4 RS232/IEEE-488.2 INTERFACE 10-921
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SECTION 1 - TECHNICAL SPECIFICATION
Additional Self Test Support
The 10-921 Intelligent Interface has a recessed self test button, “MAN TEST”. If this button is pressed a full switching self test will
occur, if an error was found the “ERR” LED will go on, use the DIAGNOSTIC? command to nd the cause. Also if the self test button
is held in for approximately 5 seconds the unit goes into a system exercising mode (which can only be stopped by holding down this
button again), this will continually exercise the relays and then run self test. Detailed self test results can then be viewed using the
DIAGNOSTIC? 1 query.
IEEE-488.2 (1987)
The Intelligent GPIB Interface has been designed to conform to the IEEE-488.2 Standard “Codes, Formats, Protocols and Common
Commands”, this carries with it many future benets. But anyone using System 10/20 can, if they desire, ignore all “standard” commands
and just use specic System 10/20 commands with no loss of switch control.
IEEE-488.2 is completely compatible with the original IEEE-488 (1978) standard. It has been designed to sit on top of IEEE-488.1 as a
second layer. IEEE-488.1 dened a complete mechanical, electrical and data exchange standard. However it stopped short of dening
any message exchange protocol, data structures or status reporting. So each equipment manufacturer used their own formats. IEEE-
488.2 denes a message exchange protocol with error handling, status reporting, dened data structures and a mandatory and optional
command set.
Its main objective has been to present a standard software interface to the applications programmer. This will greatly reduce the time
spent becoming familiar with a new instrument, for once learnt, each new instrument will have the same standard interface. Only the
device specic functions will have to be learnt.
Both the IEEE-488 and RS-232 interfaces can be run simultaneously. This is frequently used when the IEEE-488 interface is used for
programmed control while the RS-232 interface is used for occasional status reporting to a serial terminal or printer.
Powering Up With System 20 Modules
The more recent System 20 range of switching modules (particularly high density matrix) have extensive built-in self test facilities.
Because of this self testing the power-on period may take up to 1 minute instead of the 15 seconds for System 10/20 only units, please
refer to Sec 2.1 for further details.
Ethernet Connectivity
The 10-922-101 allows a System10 or System 20 to be controlled over an Ethernet network by employing a Lantronix Xport device
for ethernet connectivity. Standard SCPI/IEE488.2 commands can be issued to the system in two ways, either via a TCP/IP port or via
SNMP variables.
To communicate with the interface using TCP/IP its simply a case of establishing a connection to the correct port number (default is
10001) and sending a string in SCPI format. Any response is sent back over the same connection.
To use the SNMP method any SNMP compliant program can communicate with the interface through a number of standard and enterprise
specic MIB-II variables. The standard variables are all of the MIB-II system objects, with sysName, sysLocation and sysContact having
write access. Below is a table of the enterprise specic variables:
*Note the OID prex of 1.3.6.1.4.1.18371.1.1 (iso.org.dod.internet.private.enterprises.pickering.products.system20) is assumed.
ObjectID* Name* Access Description
.1 s20Command Read/Write Variable can be written to send a command to the system.
.2 s20Reply Read Any reply or data from the system is available by reading this.
.4.1.1 cards.cardTable.cardEntry Read A table entry for displaying information about the cards installed in the system.
.3.1 traps.s20OK Read Trap sent to indicate the system is not in an error state. Triggered by the ‘Err’ LED
on the front panel turning off.
.3.2 traps.s20Error Read Trap sent to indicate the system is in an error state. Triggered by the ‘Err’ LED on
the front panel turning on.
.3.3 traps.s20Test Read Trap sent to indicate the system has started or nished a self test. Triggered by the
changing state of the ‘TEST’ LED on the front panel.

Page 1.5
RS232/IEEE-488.2 INTERFACE 10-921
pickering SECTION 1 - TECHNICAL SPECIFICATION
Electrical & Mechanical Specications
Voltage Supplies
5Vdc ±5%.
Front Panel Connectors
24 way GPIB type specied in section 4 of the IEEE-488 (1978) standard
and RJ45 for the RS-232 port.
Rear Backplane Connector
64 way DIN 41612 style female type using rows A & C.
Approx Weight (g) 225
Dimensions (mm)
Front Panel Width 30.4
Height 128.5
Overall Length † 189
Typical Power /Current Consumption
Maximum 5V 400mA
Power 2W
Minimum 5V
Power
† Approx dimensions. Standard 160mm 3U Eurocard (as specied in DIN 41494.)

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SECTION 1 - TECHNICAL SPECIFICATION
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Page 2.1
RS232/IEEE-488.2 INTERFACE 10-921
pickering SECTION 2 - GETTING STARTED
SECTION 2 - GETTING STARTED
Power
Supply
(Posn 1)
Interface
Module
(Posn 2)
Other modules
(Not position dependent)
Figure 2.1 - Model 10-930A-002 Rear Access System10 chassis
with various modules tted
kg
PRE-OPERATION CHECKS (UNPACKING)
1. Check the module for transport damage and report any damage immediately to Pickering Interfaces.
Do not attempt to install the product if any damage is evident.
2. Position the chassis relative to any other equipment the module(s) will connect with. Ensure the chassis is not
connected to the electrical supply.
3. Ensure that the designated area for the chassis containing the module is of at and solid construction to
withstand and support the combined weight of the module(s) and chassis.
!
Refer to the Warnings and Cautions at the front of this manual
Modular products require installation in a suitable System 10/20 chassis.
The module is designed for indoor use only.
!
HARDWARE INSTALLATION
ELECTRICAL CONNECTION (CHASSIS)
1. The chassis must be electrically installed in accordance with local regional electrical codes by a qualied
engineer.
2. Ensure the power supply lead provides the necessary integrity of chassis ground.
Electrostatic discharge can damage the components on the module. To avoid such damage in handling the
board refer to page VII.
Ensure that there is adequate ventilation.

Page 2.2 RS232/IEEE-488.2 INTERFACE 10-921
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SECTION 2 - GETTING STARTED
All switching systems are usually shipped from the factory pre-congured, and are despatched with a “System
Schematic Diagram”, this describes the type, location and address of all switching modules. So most of the
installation instructions given in this and the Ancillaries manual (10-910/930) will in most cases not be required.
The 10-921 interface is factory congured as follows:
• IEEE-488 address = 10
• RS-232 conguration = 9600 baud, hardware handshake, 8 bit word with 1 stop bit and no parity.
The IEEE-488 addressing and RS-232 congurations are set via software commands (no DIP switches), to
change these settings use the CONFIG command (see section 4).
For information on the IEEE-488.2 and RS232 Interfaces and how to congure them should that be necessary
see Sections 6 and 7.
!
MODULE INSTALLATION
The Interface should be installed in accordance with the following procedure:
1. Ensure that the system is turned OFF but still connected to mains so that it remains grounded.
2. Insert the Interface Module into the relevant chassis position detailed in the Pickering 10-910M IEEE-488
GPIB System 10/20 Ancillaries manual.
3. Align the module with the backplane and screw holes at the front of the chassis.
Hold the handle whilst slowly sliding the module into the card guides until the module seats rmly into the
backplane. The front panel of the module should be ush with the front or rear panel of the chassis.
4. Screw the front panel of the module to the chassis front panel mounting rails.
5. Ensure all necessary modules including the power supply are tted to the rack and other slots blanked off
before powering up.
To achieve the correct initialisation of the sytem, ensure any slave chassis are powered up before the master
chassis.
SOFTWARE INSTALLATION
For the latest version of any drivers please refer to our web site pickeringtest.com where links to our Software
Download page will provide the driver software for the various programming environments encountered.

Page 2.3
RS232/IEEE-488.2 INTERFACE 10-921
pickering SECTION 2 - GETTING STARTED
Testing
In order for the GPIB/RS-232 Interface to work correctly there must be at least one switching module present in
the rack. Now turn on the power, check to see that the “ACTIVE” & “ERROR” LEDs ash. If “ERROR” stays on it is
usually because there are no switching modules present in the backplane.
If everything is OK both LEDs will go off. Now attach the IEEE-488 or RS-232 connector directly from your computer
to the 10-921 Interface (make sure no other devices are on the IEEE-488 bus at this stage).
To test out System 10/20, rst send the command “REPORT?”, if the Interface is happy then you should receive the
message “OK.”. The “IEEE-488” or “RS-232” LED will indicate which port is active.
Now try the following query instructions:
VIEW?tells you what is in the System 10/20 rack.
*IDN? gives information about the Interface Model.
*TST? performs a self-test (watch the LEDs ash), this should return 0.
Problems
If you cannot get the 10-921 Interface to respond, your controller software may not be set up correctly, refer to
Section 3 for a description of the message exchange protocol. If this does not solve the problem then see Section
8 or contact Pickering for further advice.
“POWER” LED (red) indicates when the 5V power supply is on.
“ACTIVE” LED (green) indicates when the interface is working (re-
ceiving, transmitting or executing commands).
“TEST” LED (yellow) is set when the system is running a self test.
“ERR” LED (red) is set whenever a “System Error” occurs (use
REPORT? to find the cause), this will only be cleared when the
machine is switched off.
“GPIB” LED (green) is set when the IEEE-488 bus is controlling the
switching system.
“RS232” LED (green) is set when the RS-232 bus is controlling the
switching system.
Figure 2.1 - Front Panel Display LEDs

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SECTION 2 - GETTING STARTED
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Page 3.1
RS232/IEEE-488.2 INTERFACE 10-921
pickering SECTION 3 - PROGRAMMING
System 10/20 Programming
The IEEE-488.2/RS-232 Interface can be programmed on two different levels:
Level 1. Suitable for learning and driving simple switching systems. Uses only those commands listed in
Section 4 “System 10/20 Commands”. Experiment with some of the examples shown on Page 4.5.
Level 2. Is used in systems which are complex and time sensitive (e.g. Automatic Test Equipment). Uses the
commands listed in both Section 4 and Section 5 “IEEE-488.2 Command Summary”.
Once you have tested and established communication with the Intelligent GPIB Interface you should start
programming using just Level 1 instructions.
RS-232 Note: In the following description of the IEEE-488 interface bus, all RS-232 commands behave in a similar
way (except those commands which are hardware dependent, e.g. SRQ).
Instruction Processing
A brief understanding of the Intelligent GPIB Interfaces’ handling of instructions is necessary. All incoming instructions
are stored in an input buffer (> 250 bytes), see Figure 3.1, which holds the data until the Parser is ready to look at
it. If the instruction is OK it is passed directly to the Execution Unit where it will be run.
If any error occurs along this path the error will be immediately reported in the Standard Event Status Register
(Figure 5.1), this register can be programmed to send an SRQ to the controller. See Appendix C for details of status
registers.
All return messages or queries are stored in an output buffer (> 250 bytes), this is used to store the message until
the controller requests it. The presence of a message in the output buffer is indicated by the MAV bit in the Status
Byte Register.
Number Formats: System 10/20 uses only integer numbers, however if a number is supplied in a non-integer format
it will always be rounded to the nearest integer value. For example 1, 1.3789, 0.89 or 100.789x10-2 will all be read
as the integer 1.
System 10/20 Message Exchange Protocol
Program Message Structure
The following description uses a simplied version of the terminology employed in the IEEE-488.2 Standard, to
which System 10/20 conforms. If a full and rigorous description is required the user should refer to that standard.
The basic element used in programming System 10/20 is the program instruction. A program instruction consists of
a sequence of data bytes sent to System 10/20 which form a command which is recognised by System 10/20. e.g.
“WRITE 1,5”.
A program message consists of a sequence of program instructions. All programming of System 10/20 should be
performed using complete program messages. The program message must be terminated either:
a) by a newline data byte (ASCII character 10 decimal)
b) by a IEEE 488.1 <EOI> sent with the last data byte
or c) by both of these together.
A program message may contain a number of program instructions. Individual program instructions within a program
message are separated by the semicolon ‘;’ (ASCII character 59 decimal), e.g. “WRITE 1,5;WRITE 1,6”.
Program Instruction Types
A program instruction may be either a command instruction, which does not cause System 10/20 to return any data
to the controller, or a query instruction, which does cause it to do so. Query instructions are distinguished by a query
mark ‘?’ (ASCII character 63 decimal) as the nal character of their mnemonic. The two types of program instruction
are reected in two forms of program message:
Command Message. A command message contains no query instructions, and does not cause System 10/20
to return any data to the controller. Such messages may be sent without restriction, e.g.
“*RST;*CLS;*SRE 32”.
SECTION 3 - PROGRAMMING

Page 3.2 RS232/IEEE-488.2 INTERFACE 10-921
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SECTION 3 - PROGRAMMING
Query Message. A query message contains one or more query instructions, and causes System 10/20 to
generate data for return to the controller. System 10/20 expects such messages to be handled
on a ‘one - for - one’ basis, i.e. the controller should issue a query message and then read the
System 10/20 response to that message before sending System 10/20 any further instructions.
An error will be detected if this protocol is violated (RESPONSE INTERRUPTED). Any attempt
to read data from System 10/20 without having previously issued a valid query message will
also cause an error (UNTERMINATED MESSAGE).
Response Messages
System 10/20 returns data to the controller in the form of a response message . A response message consists of a
sequence of bytes, terminated by a response terminator which is dened as a newline data byte (ASCII character
10 decimal) sent with IEEE 488.1 <EOI>.
Similar to the program message, a response message may contain a number of response units, such units again
being separated by the semicolon ‘;’ (ASCII character 59 decimal).
In general, a program message may contain any combination of command instruction and query instruction elements.
Where more than one query instruction is present in the program message, the message is a compound query.
The response to each query instruction will be included in the response message in the order in which the query
instructions were present in the program message, separated by semicolons. However, certain query instructions
produce a response in a form the end of which can only be unambiguously determined by the response terminator
dened above. These queries cannot have further queries compounded after them, and System 10/20 will detect an
error (ILLEGAL COMPOUND QUERY) if such an operation is attempted, e.g. “VIEW?;*IDN?”
PARSER
EXECUTION
UNIT
CONTROL DATA
COMMAND
ERROR
(CME)
EXECUTION
ERROR
(EXE)
QUERY
ERROR
(QYE)
DEVICE FUNCTIONS
IEEE-488.1 BUS
I/O CONTROL
MESSAGE
EXCHANGE
CONTROL
OUTPUT
QUEUE
(512 BYTES)
INPUT
BUFFER
(256 BYTES)
OPERATION
COMPLETE
(OPC )
POW ER
ON
(PON)
DEVICE DEPENDENT
ERROR
(DDE)
Figure 3.1 - Block Diagram of Instruction Processing