National Instruments GPIB-COM Transmitter Holding Register

Programming the GPIB-COM Section Five

GPIB-COM User Manual 5-2 © National Instruments Corporation

Transmitter Holding Register

Offset from Base I/O Address = 0

DLAB bit in Line Control Register = 0

7 654 321 0

D6 D5

D7 D4 D3 D2 D1 D0

The Transmitter Holding Register contains the character to be sent to the serial output, with bit 0

being the least significant and bit 7 the most significant. It functions identically on the GPIB-COM

and the INS8250.

Bit Mnemonic Description

7-0w D[7-0] Data Bits 7 through 0

Contents

Main Page Page FCC/DOC Radio Frequency Interference Compliance Preface Introduction to the GPIB-COM Organization of This Manual Related Documents Abbreviations Used in This Manual Contents Page Figures Tables Section One Introduction GPIB-COM Characteristics What Your Kit Should Contain Optional Equipment Page Page Switch and Jumper Settings Base I/O Address and Interrupt Selection Talk/Listen Modes Talk/Listen Address and Special Function Selection Page Installation Special Considerations When Using the GPIB-COM filename Page Function Description Section Three GPIB-COM User Manual 3-2 National Instruments Corporation Figure 3-1 shows a block diagram of the GPIB-COM. GPIB Figure 3-1. Block Diagram of GPIB-COM GPIB-COM Components Page Section Four Running Diagnostic Tests The GPIB-COM Test Commands -1 printer test -2 plotter test -c change COM configuration -q quit Section Five Programming the GPIB-COM The GPIB-COM Registers Transmitter Holding Register Receive Buffer Register Divisor Latch Least Significant Byte (LSB) Register Divisor Latch Most Significant Byte (MSB) Register Interrupt Enable Register Page Interrupt Identification Register Line Control Register Page Modem Control Register Page Line Status Register Page Modem Status Register Page Programming the Serial Adapter Polling Method Interrupt-Driven Method The GPIB-COM Controller Function Appendix A Specifications Page Multiline Interface Messages Hex Oct Dec ASCII Msg Hex Oct Dec ASCII Msg Message Definitions Multiline Interface Messages Hex Oct Dec ASCII Msg Hex Oct Dec ASCII Msg Appendix C Operation of the GPIB History of the GPIB Types of Messages Talkers, Listeners, and Controllers System Controller and Active Controller GPIB Signals Appendix C Operation of the GPIB National Instruments Corporation C-3 GPIB-COM User Manual Figure C-1 shows the arrangement of these signals on the GPIB cable connector. Data Lines Handshake Lines NRFD (not ready for data) NDAC (not data accepted) Page Page Page Configuration Restrictions User Comment Form