National Instruments GPIB-232CV, Руководство пользователя

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© National Instruments Corp. 3-1 GPIB-232CV User Manual
Chapter 3
Operation
This chapter contains information about operating the GPIB-232CV in D
mode or C mode and information about data buffering and handshaking.
The GPIB-232CV is actually a powerful 8-bit microcomputer tailored for
use as an IEEE 488-to-RS-232 protocol converter. The unit's operating
system is contained in Read-Only Memory (ROM) and can address up to
256 KB of dynamic Random-Access Memory (RAM). The GPIB-232CV
microprocessor contains an integrated Direct Memory Access (DMA)
Controller for high-speed data transfers from the GPIB circuitry. The
processor also contains an integrated memory management unit, a dynamic
RAM Controller, a clock generator, a programmable timer unit, a full
duplex UART (Universal Asynchronous Receiver Transmitter), and an
interrupt controller.
The serial port has been designed to be fully compatible with all electrical
specifications in the RS-232 standard. All GPIB functionality is provided
by an LSI GPIB Controller chip, which is programmed and maintained by
the operating system. Both the serial port and the GPIB port are interrupt
driven and feature extremely fast response times to external data transfers.
For more information on how the individual modes of operation work, refer
to the following discussions.
The following terms are specific to the discussions in this chapter:
• A * suffix after a mnemonic indicates negative logic.
• A boldface mnemonic indicates that it is a signal name, or a front panel
LED indicator.
• <CR> is the symbol for the Carriage Return character (hex 0D).
• <LF> is the symbol for the Linefeed character (hex 0A).