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Black Box IC026A-R2, IC026AE-R2 Figure 4-2. Switch SW1: Enabling or Disabling Talk-Back on Terminator.

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Figure 4-2. Switch SW1: Enabling or Disabling “Talk-Back on Terminator.”

When the serial input buffer becomes empty, the interface converter checks

the last characters sent to the IEEE bus device. If these were the IEEE bus

terminators and Talk-Back on Terminator is enabled, the IEEE bus device is

addressed to talk. Any data received by the interface converter from the bus

device is sent to the serial host.

When the last IEEE bus terminator is detected from the IEEE device, the

interface converter disables the device from sending additional information

by asserting Attention (ATN) on the bus.

If the IEEE device does not responded or finish transmission by the time

additional characters are received into the serial input buffer, the talk

sequence will be aborted to allow additional serial information to be sent to

the IEEE device.

The program example on the next page shows how this feature can be used to

communicate with a single IEEE instrument. The program example is written

in BASIC on an IBM PC or compatible and communicates with a Keithley

Model 196 DMM.

10 '

20 ' Example Program using interface converter with

25 ' the Talk-Back on Terminator feature enabled to

30 ' communicate with a Keithley Model 196 DMM

40 '

50 ' Open BASIC’s serial communications port

60 OPEN "COM1: 9600, N, 8, 2" AS 1

70 ' Set the Model 196 DMM to the 30VDC range

80 PRINT #1, "F0R3X"; ' The ; suppresses terminators

90 ' Request 10 Readings from 196”

100 FOR N=1 to 10

110 PRINT #1," " ' Output terminator

120 LINE INPUT #1, A$ ' Get reading from 196

130 PRINT A$ ' print it on the screen

140 NEXT N

150 END

Switch

Side

View

DOT

OPEN

Talk-Back on

Terminator Disabled

1 2 3 4 5 6 7 8

OPEN

Talk-Back on

Terminator Enabled

1 2 3 4 5 6 7 8

CHAPTER 4: Controller Operation

Contents

Main RS-232IEEE 488 INTERFACE CONVERTER EUROPEAN UNION DECLARATION OF CONFORMITY WARNING! Failure to follow these directives voids emission and immunity compliance. Page Page Page CONTENTS Contents RS-232IEEE 488 INTERFACE CONVERTER CONTENTS 1. Specifications WARNING! CHAPTER 1: Specifications CAUTION 2. Introduction 2.1 Description 2.2 Abbreviations CHAPTER 2: Introduction 3. Getting Started 3.1 Inspection 3.2 Configuration Figure 3-1. Factory-Default Settings. SW3 SW2 SW1 3.3 Serial Port Settings Figure 3-2. Switch SW1: Selecting the Serial Baud Rate. Figure 3-3. Switch SW1: Selecting the Serial Word Length (Data Bits). Figure 3-4. Switch SW1: Selecting the Serial Stop Bits. Figure 3-5. Switch SW2: Selecting the Serial Parity. Figure 3-6. Switch SW2: Enabling or Disabling Echo. Figure 3-7. Switch SW1: Selecting the Serial Handshake. 3.4 Selecting Terminator Substitution Figure 3-8. Switch SW2: Selecting the Serial Terminator. Figure 3-9. Switch SW3: Selecting the IEEE Bus Terminator. 3.5 Selecting the Mode Figure 3-10. Switch SW2: Selecting the Mode. 3.6 Selecting the IEEE Address Figure 3-11. Switch SW3: Selecting the IEEE Address. 3.7 Feature Selections Figure 3-12. Switch SW1: Enabling or Disabling Talk Back on Terminator in Controller Mode. Figure 3-13. Switch SW2: Enabling or Disabling Talk Back on Timeout in Controller Mode. Figure 3-14. Switch SW1: Enabling or Disabling SRQ on Last Serial Terminator in Peripheral Mode. 3.8 Serial Interface Figure 3-15. Selecting RS-232 or RS-422 Signal Levels. Figure 3-16. Rear View of the Interface Converters Serial Connector. Page Page 3.9 General CAUTION Page RS-232IEEE 488 INTERFACE CONVERTER 4.1 Controller-Mode (Serial to IEEE) Operation 4. Controller Operation 4.2 Serial and IEEE Terminator Substitution 4.3 IEEE Address Selection Figure 4-1. Switch SW3: Selecting the IEEE Address. 4.4 Talk-Back Features Figure 4-2. Switch SW1: Enabling or Disabling Talk-Back on Terminator. Figure 4-3. Switch SW2: Enabling or Disabling Talk-Back on Timeout. Page 4.5 Plotter Applications Figure 4-4. A PC-Based Graphics System. Figure 4-5. Selecting RS-232 Signal Levels. Figure 4-6. Interface Converter Settings for Use with HP 7580A Plotter on an IBM PC. SW2 SW3 SW1 Figure 4-7. MacPlot Configuration Screen. Figure 4-8. A Macintosh Based Graphics System. Interface Converter IEEE 488 RS-422 Page Figure 4-10. Interface Converter Settings for Use with HP 7580A Plotter on a Macintosh. Page 5. Peripheral Operation 5.1 Peripheral-Mode Operation 5.2 Serial and IEEE Input Buffers 5.3 IEEE Data Transfers Page RS-232IEEE 488 INTERFACE CONVERTER Figure 5-1. Switch SW1: Enabling or Disabling SRQ on Last Terminator. Figure 5-2. Serial Poll Status Byte. 5.4 Serial-Poll Status-Byte Register Page 5.5 Use of Serial and Bus Terminators 5.6 IEEE 488 Bus Implementation Page 5.7 IEEE Address Selection Figure 5-3. SW3 View for IEEE Address Selection. 6. IEEE 488 Primer 6.1 History 6.2 General Structure Page Figure 6-1. IEEE 488 Bus Structure. 6.3 Send It to My Address 6.4 Bus Management Lines 6.5 Handshake Lines Figure 6-2. IEEE Bus Handshaking. 6.6 Data Lines 6.7 Multiline Commands Page 6.8 More on Service Requests Page 7.1 Theory of Operation 7. Theory of Operation and Board Layout 7.2 Board Layout CHAPTER 7: Theory of Operation and Board Layout Figure 7-1. Component Layout of the Interface Converters Motherboard. Figure 7-2. Component Layout of the Interface Converters Serial I/O board. APPENDIX A: Sample Dumb-Terminal Program Appendix A. Sample Dumb-Terminal Program Appendix B. Character Codes and IEEE Multiline Messages Page Index INDEX