Black Box IC027A-R3 User Manual
1000 Park Drive • Lawrence, PA 15055-1018 • 724-746-5500 • Fax 724-746-0746
© Copyright 2007. Black Box Corporation. All rights reserved.
Order toll-free in the U.S.: Call 877-877-BBOX (outside U.S. call 724-746-5500)
FREE technical support 24 hours a day, 7 days a week: Call 724-746-5500 or fax 724-746-0746
Mailing address: Black Box Corporation, 1000 Park Drive, Lawrence, PA 15055-1018
Web site: www.blackbox.com • E-mail: info@blackbox.com
CUSTOMER
SUPPORT
INFORMATION
FEBRUARY 2007
IC027A-R3
488 Controller
FCC/IC RFI STATEMENTS
1
FEDERAL COMMUNICATIONS COMMISSION
AND
INDUSTRY CANADA
RADIO FREQUENCY INTERFERENCE STATEMENTS
This equipment generates, uses, and can radiate radio-frequency energy, and if not installed and used
properly, that is, in strict accordance with the manufacturer’s instructions, may cause interference to radio
communication. It has been tested and found to comply with the limits for a Class A computing device in
accordance with the specifications in Subpart B of Part 15 of FCC rules, which are designed to provide reasonable
protection against such interference when the equipment is operated in a commercial environment. Operation of
this equipment in a residential area is likely to cause interference, in which
case the user at his own expense will be required to take whatever measures may be necessary to correct
the interference.
Changes or modifications not expressly approved by the party responsible for compliance could void the user’s
authority to operate the equipment.
This digital apparatus does not exceed the Class A limits for radio noise emission from digital apparatus set out in the Radio
Interference Regulation of Industry Canada.
Le présent appareil numérique n’émet pas de bruits radioélectriques dépassant les limites applicables aux appareils numériques de
la classe A prescrites dans le Règlement sur le brouillage radioélectrique publié par Industrie Canada.
488 CONTROLLER
2
INSTRUCCIONES DE SEGURIDAD (Normas Oficiales Mexicanas Electrical Safety Statement)
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.
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.
3
EUROPEAN UNION DECLARATION OF CONFORMITY
EUROPEAN UNION DECLARATION OF CONFORMITY
To maintain safety, emission, and immunity standards of this declaration, the following conditions must
be met.
• Serial and IEEE cables must have a braided shield connected circumferentially to their connectors’
metal shells.
• All cable screw locks must be tightened at both ends of the cable.
• The host computer must be properly grounded.
• Some inaccuracy is to be expected when I/O leads are exposed to RF fields or transients.
• The operator must observe all safety cautions and operating conditions specified in the documentation
for all hardware used.
• The host computer, peripheral equipment, power sources, and expansion hardware must be CE
compliant.
• All power must be off to the device and externally connected equipment before internal access to the
device is permitted.
• An external power supply is provided with this product. Its input is 100–240 VAC, 50–60 Hz, 0.5 A
maximum power draw. Its 9-VDC, 15 W maximum, 1.7 A output connects to the power input of the unit.
• The RS-232/422 terminal is meant to be connected only to devices with serial-communications-level
signals. The IEEE 488 terminal is meant to be used only with non-isolated IEEE 488 systems. The
common mode voltage (cable shell to earth) must be zero.
• Terminal Installation Category for CE Compliance is Category 1.
• Operating environment for CE compliance is: Indoor use at altitudes below 2000 m, 0 to 40°C, 80%
maximum RH up to 31°C decreasing linearly 4%RH/°C to 40°C.
WARNING!
Noted conditions pertain to potential safety hazards. When you see the WARNING!,
IMPORTANT!, or CAUTION! notes, carefully read the information and be alert to the
possibility of personal injury.
Failure to follow these directives voids emissions and immunity compliance.
488 CONTROLLER
4
TRADEMARKS USED IN THIS MANUAL
Macintosh is a registered trademark of Apple Computer, Inc.
BLACK BOX and the Double Diamond logo are registered trademarks of BB Technologies, Inc.
Hewlett-Packard and HP are registered trademarks of Hewlett-Packard.
AT and IBM are registered trademarks of IBM Corporation.
Any other trademarks mentioned in this manual are acknowledged to be the property of the trademark owners.
CONTENTS
5
Chapter Page
1. Specifications....................................................................................................................................................8
2. Introduction ...................................................................................................................................................10
2.1 Description............................................................................................................................................10
2.2 What’s Included....................................................................................................................................10
2.3 Abbreviations ........................................................................................................................................11
3. Getting Started ...............................................................................................................................................12
3.1 Configuration .......................................................................................................................................12
3.2 Serial-Port Settings................................................................................................................................14
3.2.1 Serial Baud Rate .......................................................................................................................14
3.2.2 Serial Word Length (Data Bits)...............................................................................................15
3.2.3 Serial Stop Bits .........................................................................................................................16
3.2.4 Serial Parity...............................................................................................................................16
3.2.5 Serial Echo................................................................................................................................17
3.2.6 Serial Handshake .....................................................................................................................17
3.3 Selecting Terminator Substitution.......................................................................................................18
3.3.1 Serial Terminator .....................................................................................................................18
3.3.2 IEEE Bus Terminator...............................................................................................................19
3.4 Selecting the Mode...............................................................................................................................19
3.5 Selecting the IEEE Address..................................................................................................................20
3.6 Feature Selections.................................................................................................................................21
3.6.1 Controller Pass-Thru Features ................................................................................................21
3.6.2 Peripheral Pass-Thru Features ................................................................................................22
3.7 Serial Interface .....................................................................................................................................22
3.7.1 RS-232/RS-422 Signal Level Selection....................................................................................22
3.7.2 Serial Signal Descriptions ........................................................................................................23
3.7.3 Serial-Cable Wiring Diagrams .................................................................................................24
3.8 General Operation ...............................................................................................................................26
3.9 Is Anyone Out There? ..........................................................................................................................27
4. IEEE Operating Modes..................................................................................................................................28
4.1 Introduction..........................................................................................................................................28
4.2 Operating Mode Transitions................................................................................................................28
4.3 System Controller Mode ......................................................................................................................30
4.4 System Controller, Not Active Controller Mode.................................................................................31
4.5 Not System Controller Mode ...............................................................................................................33
4.6 Active Controller, Not System Controller Mode.................................................................................34
4.7 Controller Pass-Thru Mode..................................................................................................................34
4.8 Peripheral Pass-Thru Mode .................................................................................................................34
5. Command Descriptions .................................................................................................................................35
5.1 Introduction..........................................................................................................................................35
5.2 Command-Description Format............................................................................................................36
5.2.1 Syntax........................................................................................................................................36
5.2.2 Response...................................................................................................................................38
5.2.3 Mode .........................................................................................................................................38
5.2.4 Bus States ..................................................................................................................................39
5.3 Memory Use ..........................................................................................................................................40
5.4 The Commands ....................................................................................................................................40
Contents
488 CONTROLLER
6
Contents (continued)
Chapter Page
6. Controller Pass-Thru Operation ...................................................................................................................74
6.1 Introduction..........................................................................................................................................74
6.2 Serial and IEEE Terminator Substitution ...........................................................................................74
6.3 IEEE Address Selection ........................................................................................................................75
6.4 Talk Back On Terminator.....................................................................................................................75
6.5 Plotter Applications..............................................................................................................................76
6.6 Printer Applications .............................................................................................................................78
7. Peripheral Pass-Thru Operation ...................................................................................................................79
7.1 Introduction..........................................................................................................................................79
7.2 Serial and IEEE Input Buffers .............................................................................................................79
7.3 IEEE Data Transfers..............................................................................................................................80
7.3.1 Blind Bus Data Transfers .........................................................................................................80
7.3.2 Controlled Bus Data Transfers................................................................................................81
7.4 Serial Poll Status Byte Register ............................................................................................................82
7.5 Use of Serial and Bus Terminators ......................................................................................................83
7.6 IEEE 488 Bus Implementation ............................................................................................................83
7.6.1 My Talk Address (MTA)...........................................................................................................83
7.6.2 My Listen Address (MLA) .......................................................................................................83
7.6.3 Device Clear (DCL and SDC) .................................................................................................84
7.6.4 Interface Clear (IFC)...............................................................................................................84
7.6.5 Serial Poll Enable (SPE) ..........................................................................................................84
7.6.6 Serial Poll Disable (SPD) .........................................................................................................84
7.6.7 Unlisten (UNL)........................................................................................................................84
7.6.8 Untalk (UNT) ..........................................................................................................................84
7.7 IEEE Address Selection ........................................................................................................................84
8. IEEE 488 Primer.............................................................................................................................................85
8.1 History ...................................................................................................................................................85
8.2 General Structure .................................................................................................................................85
8.3 Send It To My Address..........................................................................................................................87
8.4 Bus Management Lines ........................................................................................................................87
8.4.1 Attention (ATN) ......................................................................................................................87
8.4.2 Interface Clear (IFC)...............................................................................................................87
8.4.3 Remote Enable (REN).............................................................................................................87
8.4.4 End or Identify (EOI)..............................................................................................................87
8.4.5 Service Request (SRQ) ............................................................................................................87
8.5 Handshake Lines ..................................................................................................................................88
8.5.1 Data Valid (DAV) .....................................................................................................................88
8.5.2 Not Ready For Data (NRFD) ...................................................................................................88
8.5.3 Not Data Accepted (NDAC)....................................................................................................88
8.6 Data Lines .............................................................................................................................................89
8.7 Multiline Commands............................................................................................................................89
8.7.1 Go To Local (GTL)..................................................................................................................89
8.7.2 Listen Address Group (LAG) ..................................................................................................89
8.7.3 Unlisten (UNL)........................................................................................................................89
8.7.4 Talk Address Group (TAG) .....................................................................................................89
8.7.5 Untalk (UNT) ..........................................................................................................................89
8.7.6 Local Lockout (LLO) ..............................................................................................................89
8.7.7 Device Clear (DCL) .................................................................................................................89
CONTENTS
7
Chapter Page
8.7.8 Selected Device Clear (SDC)...................................................................................................89
8.7.9 Serial Poll Disable (SPD) .........................................................................................................89
8.7.10 Serial Poll Enable (SPE) ..........................................................................................................89
8.7.11 Group Execute Trigger (GET)................................................................................................89
8.7.12 Take Control (TCT).................................................................................................................89
8.7.13 Secondary Command Group (SCG).......................................................................................90
8.7.14 Parallel Poll Configure (PPC) .................................................................................................90
8.7.15 Parallel Poll Unconfigure (PPU) ............................................................................................90
8.8 More On Service Requests ...................................................................................................................90
8.8.1 Serial Poll..................................................................................................................................90
8.8.2 Parallel Poll...............................................................................................................................90
9. Theory of Operation & Board Layout ..........................................................................................................91
9.1 Theory of Operation ............................................................................................................................91
9.2 Board Layout.........................................................................................................................................92
Appendix A: 488 Controller Command Summary.............................................................................................94
Appendix B: 488 Controller Error Messages......................................................................................................97
Appendix C: Character Codes and IEEE Multiline Messages ...........................................................................99
Appendix D: Sample Programs .........................................................................................................................101
488 CONTROLLER
8
488 Controller
IEEE 488-1978 Implementation: C1, C2, C3, C4, and C28 controller subsets; SH1, AH1, T6,
TE0, L4, LE0, SR1, RL0, PP0, DC1, DT1, E1
Terminators: Selectable CR, LF, LF-CR, and CR-LF with EOI
Connector: Standard IEEE 488 connector with metric studs
Serial Interface
EIA RS-232C: AB, BA, BB, CA, CB
EIA RS-422A: Balanced voltage on TxD and RxD
Character Set: Asynchronous bit serial
Output Voltage: ±5 volts minimum (RS-232C); 3.5 volts typical (RS-422A)
Input Voltage: ±3 volts minimum; ±15 volts maximum
Baud Rate: Selectable 110, 300, 600, 1200, 1800, 2400, 3600, 4800, 7200,
9600, 19,200, and 57,600
Data Format: Selectable 7 or 8 data bits; 1 or 2 stop bits; odd, even, mark,
space and no parity on transmit
Duplex: Full with Echo/No Echo
Serial Control: Selectable CTS/RTS or X-ON/X-OFF
Terminators: Selectable CR, LF, LF-CR, and CR-LF
Connector: DB25; RS-232C DCE configured
1. Specifications
9
CHAPTER 1: Specifications
General
Data Buffer: 32,000 characters total, dynamically allocated
Environment: 0 to 50°C; 0 to 70% R.H. to 35°C; Linearly derate
3% R.H./°C from 35 to 50°C
Controls: Power switch (external), IEEE and serial parameter switches
(internal); jumper selection of RS-232 or RS-422 operation
(internal)
Certification: FCC, CE
Indicators: (4) LEDs: Talk, Listen, SRQ, Error, and Power
Power: Input: 100–240 VAC, autosensing, 50–60 Hz,
0.5 A maximum;
Output: 9 V, 15 W maximum, 1.7 A
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)
WARNING!
Do not use this interface outdoors. The interface is intended for indoor use only. Using this
equipment outdoors could result in equipment failure, bodily injury, or death.
CAUTION
Do not connect AC line power directly to the 488 Controller. Direct AC connection will
damage equipment.
488 CONTROLLER
10
2.1 Description
The 488 Controller converts a host RS-232 or RS-422 computer into an IEEE 488 bus talker, listener, and
controller. The 488 Controller provides full IEEE 488-1978 bus implementation including advance
capabilities such as PASS CONTROL, RECEIVE CONTROL, PARALLEL POLL, SERIAL POLL, and
SECONDARY ADDRESSING. The device may be located several hundred feet from the host and may
control as many as fourteen 488 bus instruments. In the noncontroller mode the 488 Controller converts
the host into a bus peripheral for data processing and mass storage.
The 488 Controller interprets simple high-level commands sent from the computer’s serial port and
performs the necessary, and usually complex, bus control and handshaking. The commands and protocol
are similar to those used by the Hewlett-Packard
®
HP-85 computer.
Additional features provide a transparent IEEE to serial converter and a serial to IEEE pass-thru controller.
As a serial-to-IEEE-488 converter, the 488 Controller receives data from a serial host, then automatically
performs the bus sequences necessary to send this data to the IEEE 488 device. If desired, data can be
requested from the IEEE 488 device and returned to the host.
As an IEEE-488-to-serial converter, the 488 Controller is a peripheral to an IEEE 488 controller. Data
received from the controller is sent to the serial device and data received from the serial device is buffered
for transmission to the IEEE 488 controller. The 488 Controller can inform the host, by the serial poll-status
byte, that it has received data from the serial device.
2.2 What’s Included
Your package should include the IEEE 488 controller, an AC power cable, and this user’s manual.
2. Introduction
11
CHAPTER 2: Introduction
2.3 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
REN Remote Enable
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
488 CONTROLLER
12
3.1 Configuration
Three internal DIP switches set the interface’s configuration.
NOTE
Selectable functions are read only at power-on and should only be set prior to applying
power to the interface.
The figures below and on the next page illustrate the factory-default conditions, which are:
Serial Por
t: IEEE:
9600 Baud Mode = System Controller
8 Data Bits Address = 10
2 Stop Bits Bus Terminator = CR-LF; EOI Disabled
No Parity Talk-Back Enabled
Serial Terminator = CR-LF
Echo Disabled
RTS/CTS Handshake
Figure 3-1. SW3 factory-default settings.
1 2 3 4 5
6
7 8
OPEN
SW3
IEEE Addr
IEEE Term
EOI
10
CR-LF
Disabled
Switch
Side
View
DOT
3. Getting Started
13
CHAPTER 3: Getting Started
Figure 3-2. SW2 factory-default settings.
Figure 3-3. SW1 factory-default settings.
1 2 3 4 5 6 7 8
OPEN
SW1
Baud Rate
Handshake
Word Length
9600
RTS/CTS
8 Data Bits
Switch
Side
View
DOT
Pass-Thru Feature
Enabled
Stop Bits
2 Stop Bits
1 2 3 4 5 6 7 8
OPEN
SW2
Mode
Serial Term
Echo
SC
CR-LF
Switch
Side
View
DOT
Parity
No Echo
No Parity
488 CONTROLLER
14
The 488 Controller is configured as an IEEE controller. In this mode, the 488 Controller allows an RS-232
host computer to control up to 14 IEEE 488 devices. This mode of operation is described in detail, along
with its command descriptions, in Chapters 4 and 5. These sections also cover the Peripheral mode of
operation.
The 488 Controller can be configured to transparently communicate with a single IEEE peripheral, such
as a plotter. This Controller Pass-Thru mode is described in detail in Chapter 6.
The 488 Controller may also be configured as a transparent IEEE Pass-Thru Peripheral. As a Pass-Thru
Peripheral, it allows an IEEE controller to communicate with an RS-232 device. The Peripheral Pass-Thru
operation mode is described in detail in Chapter 7.
To modify any of these defaults, follow this simple procedure:
1) Disconnect the power supply from the AC line and from the 488 Controller. Also disconnect any IEEE
or serial cables prior to disassembly.
WARNING
Never open the 488 Controller’s case while it is connected to the AC line. Failure to
observe this warning may result in equipment failure, personal injury, or death.
2) Place the 488 Controller upside down on a flat surface. Remove the four screws located near the rubber
feet.
3) Return the interface to the upright position and carefully remove the top cover.
4) Change whichever DIP-switch settings you need to change.
5) When you have made all of your changes, reverse this procedure to reassemble the 488 Controller.
3.2 Serial-Port Settings
The first parameters to configure are those that correspond to the RS-232 port. These include baud rate,
word length, number of stop bits, parity selection, and type of RS-232 handshake. Each of these is described
in Sections 3.2.1 through 3.2.6.
3.2.1 S
ERIAL
BAUD RATE
The “baud rate” is the number of serial bits per second transferred into and out of the serial interface.
SW1-1 through SW1-4 determine the serial baud rate. The factory-default baud rate is 9600 baud. Baud rates
may be selected from 110 to 57,600 baud. Refer to the following diagram for specific baud rates.
15
CHAPTER 3: Getting Started
Figure 3-4. Switch SW1: Selecting the serial baud rate.
3.2.2 SERIAL WORD LENGTH (DATA BITS)
SW1-6 determines the number of data bits, often referred to as word length, for each serial character
transmitted or received. The factory default is 8 data bits.
Figure 3-5. Switch SW1: Selecting the serial word length (data bits).
1 2 3 4 5
6
7 8
OPEN
8 Data Bits
1 2 3 4 5
6
7 8
OPEN
7 Data Bits
Switch
Side
View
DOT
488 CONTROLLER
16
3.2.3 SERIAL S
TOP BITS
Switch SW1-8 determines the number of stop bits contained in each serial character transmitted
and received. The factory default is 2 stop bits.
Figure 3-6. Switch SW1: Selecting the serial stop bits.
3.2.4 S
ERIAL P
ARITY
Serial parity is selected with S2-6 through S2-8. The 488 Controller generates the selected parity during serial
transmissions but it does not check parity on data that is received. The factory default is parity disabled.
Figure 3-7. Switch SW2: Selecting the serial parity.
Switch
Side
View
DOT
1 2 3 4 567 8
OPEN
Mark Parity
1 2 3 4 567 8
OPEN
Odd Parity
1 2 3 4 567 8
OPEN
Space Parity
1 2 3 4 567 8
OPEN
Even Parity
1 2 3 4 567 8
OPEN
Parity Disabled
Switch
Side
View
DOT
1 2 3 4 5
6
7 8
OPEN
2 Stop Bits
1 2 3 4 5
6
7 8
OPEN
1 Stop Bit
17
CHAPTER 3: Getting Started
3.2.5 SERIAL E
CHO
Serial data sent to the 488 Controller will be echoed back to the serial host if SW2-5 is set to the open
position. The factory default is Echo Disabled.
Figure 3-8. Switch SW2: Enabling or disabling echo.
3.2.6 S
ERIAL HANDSHAKE
Switch SW1-5 is used to select hardware (RTS/CTS) or software (X-ON/X-OFF) serial handshake control.
With X-ON/X-OFF, the 488 Controller issues an X-OFF character (ASCII value of &H13) when its buffer
memory is near full. When the X-OFF character is sent, there are still more than 1000 character locations
remaining to protect against buffer overrun. When it is able to accept more information, the 488 Controller
issues an X-ON character (ASCII value of &H11). The 488 Controller also accepts X-ON/X-OFF on transmit
from the serial host it is communicating with. RTS/CTS serial control becomes inactive when X-ON/X-OFF
is enabled. The RTS output is, however, set to an active high state. The CTS input is not used for this
handshake and may be left floating (unconnected).
With RTS/CTS, the 488 Controller unasserts RTS (sets RTS low) when its buffer memory is near full. When
RTS is unasserted, there are still more than 1000 character locations remaining to protect against buffer
overrun. When it is able to accept more information, the 488 Controller asserts RTS (sets RTS high). The
488 Controller will not transmit data to the serial host if it detects the CTS input unasserted (low) when
configured for this hardware handshake.
The factory-default serial control is hardware, RTS/CTS.
Figure 3-9. Switch SW1: Selecting the serial handshake.
Switch
Side
View
DOT
1 2 3 4 5
6
7 8
OPEN
RTS/CTS
1 2 3 4 5
6
7 8
OPEN
X-ON/X-OFF
1 2 3 4 5
6
7 8
OPEN
Echo Disabled
1 2 3 4 5
6
7 8
OPEN
Echo Enabled
Switch
Side
View
DOT
488 CONTROLLER
18
3.3 Selecting Terminator Substitution
In the Controller and Peripheral Modes, the 488 Controller is not sensitive as to whether CR or LF is used
as a serial input terminator to a command. In general, it requires only one of either to cause command
execution. The IEEE input terminator is fixed to LF. The switches that allow terminator selection, shown in
the following diagrams, set only the serial output and IEEE output terminators for these operation modes.
In the transparent Pass-Thru modes, the 488 Controller can be configured to provide RS-232-to-IEEE 488
and IEEE-488-to-RS-232 terminator substitution. This is useful when interfacing an RS-232 device which only
issues carriage return (CR) as an output terminator to an IEEE controller which expects a carriage return
followed by a line feed (CR-LF).
In the above case, the serial terminator should be selected for CR Only while the IEEE terminator is set to
CR-LF. When a serial CR character is received, it is discarded, and an IEEE CR-LF is substituted for it. In the
IEEE-to-RS-232 direction, the IEEE CR is unconditionally discarded. When it receives the IEEE LF, a serial
CR is substituted.
To make the 488 Controller totally data transparent in the Pass-Thru modes, set both the serial and IEEE
terminators to be CR Only or LF Only.
3.3.1 S
ERIAL TERMINATOR
SW2-3 and SW2-4 select the serial terminators for the serial input (Pass-Thru Modes Only) and output.
The factory default is CR-LF.
Figure 3-10. Switch SW2: Selecting the serial terminator.
Switch
Side
View
DOT
CR Only
1 2 3 4 5
6
7 8
OPEN
LF-CR
1 2 3 4 5
6
7 8
OPEN
1 2 3 4 5
6
7 8
OPEN
LF Only
1 2 3 4 5
6
7 8
OPEN
CR-LF
19
CHAPTER 3: Getting Started
3.3.2 IEEE BUS T
ERMINATOR
SW3-6 through SW3-8 set the IEEE bus terminators used for data sent or received (Pass-Thru modes only)
by the 488 Controller. EOI, a line used to signal the end of a multiple character bus transfer, may also be
enabled. If enabled, EOI is asserted when the last selected bus terminator is sent. Factory default is CR-LF
with EOI disabled.
Figure 3-11. Switch SW3: Selecting the IEEE bus terminator.
3.4 Selecting the Mode
SW2-1 and SW2-2 set the major operating mode of the 488 Controller. There are four distinct modes
of operation.
1. System Controller
2. Peripheral
3. Controller Pass-Thru
4. Peripheral Pass-Thru
Switch
Side
View
DOT
1 2 3 4 5
6
7 8
OPEN
LF Only
1 2 3 4 5
6
7 8
OPEN
CR-LF
1 2 3 4 5
6
7 8
OPEN
CR Only
1 2 3 4 5
6
7 8
OPEN
LF-CR
1 2 3 4 5
6
7 8
OPEN
EOI Disabled
1 2 3 4 5
6
7 8
OPEN
EOI Enabled
488 CONTROLLER
20
As a System Controller, the 488 Controller accepts simple high-level ASCII commands from a serial host. It
interprets these commands and performs the required bus action to bidirectionally communicate with up to
14 IEEE devices. As a Peripheral, the 488 Controller becomes a bus device. It accepts simple high-level ASCII
commands from a serial host and interprets these commands and status to communicate with another IEEE
controller. Applications include computer-controlled automatic test systems. These operation modes are
discussed in Chapters 4 and 5.
The IEEE Controller Pass-Thru (RS-232 to IEEE Converter) mode allows a serial host device to send data to
a single IEEE bus peripheral. Applications include interfacing a listen-only or addressable IEEE
printer/plotter to a serial printer port. Refer to Chapter 6 for more detailed information on the Controller
Pass-Thru operation mode.
The Peripheral Pass-Thru mode is used when interfacing a serial device to an IEEE controller. Data which
is sent by the IEEE controller to the 488 Controller is transmitted out its serial port. Data received from the
serial device is buffered by the 488 Controller until it is read by the IEEE controller. Refer to Chapter 7 for
more detailed information on the Peripheral Pass-Thru operation mode.
The factory default is the System Controller mode.
Figure 3-12. Switch SW2: Selecting the mode.
3.5 Selecting the IEEE Address
SW3-1 through SW3-5 select the IEEE bus address of the 488 Controller when in the System Controller,
Peripheral and Peripheral Pass-Thru modes. These same switches are used in the Controller Pass-Thru mode
to select the address of the device that will be controlled. (Refer to Chapter 7 for additional information.)
The address is selected by simple binary weighting, with SW3-1 being the least significant bit and SW3-5 the
most significant. The factory default is address 10.
Listen Only is a special type of Peripheral Pass-Thru operation. In the Listen Only mode the 488 Controller
accepts all data transmitted on the bus, ignoring any bus addressing, and transfers it out its serial port. The
488 Controller is set to Listen Only mode by setting its address to 31. If the IEEE address is set to 31 in the
System Controller, Peripheral, or Peripheral Pass-Thru mode, it is adjusted to address 30.
Switch
Side
View
DOT
1 2 3 4 5
6
7 8
OPEN
Controller Pass-Thru
1 2 3 4 5
6
7 8
OPEN
Peripheral Pass-Thru
1 2 3 4 5
6
7 8
OPEN
Peripheral
System Controller
1 2 3 4 5
6
7 8
OPEN
21
CHAPTER 3: Getting Started
Figure 3-13. Switch SW3: Selecting the IEEE address.
3.6 Feature Selections
The functions of the remaining switches are dependent on the mode selected. A brief description of each
of these features follows. Refer to the listed sections for additional information.
3.6.1 CONTROLLER PASS-THRU FEATURES
In the IEEE Controller (RS-232-to-IEEE-488 converter) mode, SW1-7 determines whether the interface
should, after sending the IEEE bus terminators, address the attached bus device to talk. The factory default
is Talk-back On Terminator enabled.
Refer to Chapter 6 for complete details on these features.
Figure 3-14. Switch SW1: Enabling or disabling “Talk Back on Terminator” in Controller mode.
Switch
Side
View
DOT
1 2 3 4 5
6
7 8
OPEN
Talk-Back on
Terminator Disabled
1 2 3 4 5
6
7 8
OPEN
Talk-Back on
Terminator Enabled
488 CONTROLLER
22
3.6.2 PERIPHERAL P
ASS-THRU FEATURES
In the Peripheral Pass-Thru (IEEE-488-to-RS-232 converter) mode, SW1-7 enables the interface to assert
the SRQ IEEE bus interface line to indicate that it has received the last-switch-selected serial terminator
character from the serial device.
Figure 3-15. Switch SW1: Enabling or disabling SRQ on last serial terminator in Peripheral mode.
3.7 Serial Interface
The 488 Controller has the ability to output signal levels that are compatible with either RS-232 or RS-422.
An internal DIP shorting plug determines which electrical specification is chosen. If the interface is to be
connected to an IBM
®
PC or compatible, select the RS-232 level. If it will be connected to a Macintosh®, use
the RS-422 level. For connection to other computers, refer to the manufacturer’s manual to determine
which levels are supported.
3.7.1 RS-232/RS-422 S
IGNAL LEVEL SELECTION
The 488 Controller’s factory default signal levels are compatible with RS-232. To select RS-422 levels,
carefully remove the 8-position shorting plug with a small flat-blade screwdriver from J106. Install the
DIP jumper into J205, making certain that all shorting plug pins are inserted correctly.
Figure 3-16. Selecting RS-232 or RS-422 signal levels.
Switch
Side
View
DOT
1 2 3 4 5
6
7 8
OPEN
SRQ on Last
Terminator Disabled
1 2 3 4 5
6
7 8
OPEN
SRQ on Last
Terminator Enabled
Shorting Plug
RS-232
RS-422
23
CHAPTER 3: Getting Started
3.7.2 SERIAL S
IGNAL DESCRIPTIONS
The 488 Controller is equipped with a standard DB25 female connector on its rear panel and requires
a standard DB25 male mating connector. The 488 Controller’s connector is configured as DCE type
equipment for RS-232 communications, which means the 488 Controller always transmits data on Pin 3
and receives data on Pin 2. The following lists and describes the RS-232 and RS-422 signals provided on
the 488 Controller.
Figure 3-17. Rear view of the 488 Controller’s serial connector.
-RxD Receive Data—Input—Pin 2
This pin accepts serial data sent by the RS-232 or RS-422 host. The serial data is expected
with the word length, baud rate, stop bits, and parity selected by the internal switches. The
signal level is low true.
-TxD Transmit Data—Output—Pin 3
This pin transmits serial data to the RS-232 or RS-422 host. The serial data is sent with the
word length, baud rate, stop bits, and parity selected by the internal switches. The signal
level is low true.
CTS Clear To Send—Input—Pin 4
The CTS input is used as a hardware-handshake line to prevent the 488 Controller from
transmitting serial data when the RS-232 host is not ready to accept it. When RTS/CTS
handshake is selected on the internal switches, the 488 Controller will not transmit data
out -TxD while this line is unasserted (lowered). If the RS-232 host is not capable of driving
this line it can be connected to the Vtest output (Pin 6) of the 488 Controller. If X-ON/X-OFF
handshake is selected, the CTS line is not tested to determine if it can transmit data.
RTS Request To Send—Output—Pin 5
The RTS output is used as a hardware handshake line to prevent the RS-232/RS-422 host
from transmitting serial data if the 488 Controller is not ready to accept it. When RTS/CTS
handshake is selected on the internal switches, the 488 Controller will drive the RTS output
high when there are more than 1000 character locations available in its internal buffer. If
the number of available locations drops to less than 1000, the 488 Controller will unassert
(lower) this output. If X-ON/X-OFF handshake is selected, the RTS line will be permanently
driven active high.
13 1
25 14
-RXD
-TXD
CTS
RTS
+VTEST
GND
+VTEST
+RXD
+TXD
488 CONTROLLER
24
+Vtest Test Voltage—Output—Pin 6
This pin is connected to +5 volts through a 1K resistor. It is also common to Vtest on pin 9.
Gnd Ground—Pin 7
This pin sets the ground reference point for the other RS-232 inputs and outputs.
+Vtest Test Voltage—Output—Pin 9
This pin is connected to 5 volts through a 1K resistor. It is also common to Vtest on pin 6.
+RxD Receive Data Plus—Input—Pin 14
This pin accepts serial data sent by the RS-422 host. The serial data is expected with the word
length, baud rate, stop bits, and parity selected by the internal switches. The signal level is
high true and only connected to this pin when RS-422 operation is selected. It is 180 degrees
out of phase with -RxD.
+TxD Transmit Data Plus—Output—Pin 16
This pin transmits serial data to the RS-422 host. The serial data is sent with the word length,
baud rate, stop bits, and parity selected by the internal switches. The signal level is high true
and only connected to this pin when RS-422 operation is selected. It is 180 degrees out of
phase with -TxD.
3.7.3 S
ERIAL-CABLE WIRING DIAGRAMS
If a cable was not purchased with the 488 Controller, the following diagrams will help you make your own
cable. Simple soldering skills and attention to detail will ensure successful construction.
Figure 3-18. Wiring diagram: Macintosh to 488 Controller.
25
CHAPTER 3: Getting Started
Figure 3-19. Wiring diagram: IBM PC or compatible with DB25
serial connector to 488 Controller (RS-232).
Figure 3-20. Wiring diagram: IBM AT
®
or compatible with DB9
serial connector to 488 Controller (RS-232).
NOTE
Standard AT 9-pin-to-25-pin adapter cables are not wired as shown above and will not work
with the 488 Controller.
DCD 1
-RxD 2 3 -TxD
-TxD 3 2 -RxD
DTR 4
Gnd 5 7 Gnd
DSR 6
RTS 7 4 CTS
DB9 Female DB25 Male
CTS 8 5 RTS
488 CONTROLLER
26
3.8 General Operation
Refer to the following sections for specific operational modes. This section gives a general test of functionality. After setting the power-on defaults and reassembling the 488 Controller, plug the power-supply
connector into the rear jack on the interface.
CAUTION
Never plug the power supply into the 488 Controller while it is connected to AC line power.
If you do, you could damage the 488 Controller.
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 plugging the power supply connector into the 488 Controller, plug the power supply into AC line
power. Turn the rear-panel power switch ON (the “1” position). All the front-panel indicators should light
momentarily while the 488 Controller performs an internal ROM and RAM self-check. At the end of this
self-check, all indicators except POWER should turn off.
If there is an error in the ROM checksum, all of the LEDs will remain on. Flashing LEDs indicate a RAM
failure. Should such an error occur, turn the rear-panel switch to the OFF (0) position and retry the above
procedure.
If the front-panel indicators do not flash and the POWER indicator does not remain lit, there may not be
any power supplied to the interface. If this happens, check the AC line and the power supply’s rear-panel
connection.
If the controller operates properly, connect an interface cable to the 488 Controller’s rear (DB25)
connector. Connect the other end to the host’s serial port. Except for connecting IEEE bus instruments, the
488 Controller is installed and ready to use.
WARNING
The 488 Controller makes its earth ground connection through the serial interface cable. It
should only be connected to IEEE bus devices after being first connected to the host.
Failure to do so may allow the 488 Controller to float to a bus device test voltage. This
could result in damage to the 488 Controller, personal injury, or death.
27
CHAPTER 3: Getting Started
3.9 Is Anyone Out There?
Before connecting any IEEE bus devices to the 488 Controller, try this simple operational check. The 488
Controller must be configured for either System Controller or Peripheral mode operation. This test will
not work in either of the Pass-Thru modes.
Running BASIC on the host, or any programming language which supports the serial ports, type the
following (or its equivalent).
OPEN "COM1:9600, N, 8, 2, cd, ds" AS 1 [Return]
PRINT #1,"HELLO" [Return]
LINE INPUT #1,A$ [Return]
PRINT A$ [Return]
The 488 Controller will respond with (and the host will display):
488 Controller Revision N.N Copyright (C) 1988
where N.N is the release and revision number of the firmware.
If you obtain the response above, then your 488 Controller is fine and ready to connect your host to the
powerful IEEE-488 General Purpose Interface Bus. If you did not receive the message above, check that the
interface cable is properly connected and fits. If the 488 Controller is not installed correctly, call Black Box
Technical Support.
488 CONTROLLER
28
4.1 Introduction
There are four types of IEEE bus devices: Active Controllers, Peripherals, Talk-Only devices, and ListenAlways devices. Talk-Only and Listen-Always devices are usually used together, in simple systems, such as
a Talk-Only digitizer sending results to a Listen-Always plotter. In these simple systems, no controller is
needed, because the talker assumes that it is the only talker on the bus, and the listener(s) assume that
they are all supposed to receive all the data sent over the bus. This is a simple and effective method of
transferring data from one device to another, but is not adequate for more complex systems where, for
example, one computer is controlling many different bus devices.
In more complex systems, the Active Controller sends commands to the various bus Peripherals telling them
what to do. Commands such as Unlisten, Listen Address Group, Untalk, and Talk Address Group are sent by
the controller to specify which device is to send data, and which devices are to receive it. For more details
about the IEEE bus protocols, see Chapter 8.
When an IEEE bus system is first turned on, some device must be the Active Controller. This device is the
System Controller and always keeps some control of the bus. In particular, the System Controller controls
the Interface Clear (IFC) and Remote Enable (REN) bus management lines. By asserting Interface Clear,
the System Controller forces all the other bus devices to stop their bus operations, and regains control as
the Active Controller.
4.2 Operating Mode Transitions
The System Controller is initially the Active Controller. It can, if desired, pass control to another device
and thereby make that device the Active Controller. The System Controller remains the System Controller.
The device to which control is passed must be able to take on the Active Controller role. It would make no
sense to try to pass control to a printer. Control should only be passed to other computers that are capable,
and ready, to become the Active Controller. There must be exactly one System Controller on the IEEE bus.
All other potential controllers must be configured as Peripherals when they power on.
The state diagram on the next page shows the relationships between the various operating modes. The top
half of the state diagram shows the System Controller’s two operating states. At power-on, it is the active
controller. It directs the bus transfers by sending the bus commands mentioned previously. It also has
control of the Interface Clear and Remote Enable bus lines. The System Controller can pulse Interface
Clear to reset all other bus devices.
As shown in the diagram, the System Controller can pass control to some other bus device and thereby
become a Peripheral to the new Active Controller. If the System Controller receives control from the new
Active Controller, then it will once again become the Active Controller. The System Controller can also
force the Active Controller to relinquish control by asserting the Interface Clear signal.
The bottom half of the state diagram shows the two operating states of a Not System Controller device. At
power on, it is a Peripheral to the System Controller, which is the Active Controller. If it receives control
from the Active Controller, it becomes the new Active Controller. Even though it is the Active Controller, it
is still not the System Controller. The System Controller can force the Active Controller to give up control
by asserting Interface Clear. The Active Controller can also give up control by passing control to another
device, which may or may not be the System Controller.
4. IEEE Operating Modes
Loading...