Chapter 4 Register Bit Descriptions
© National Instruments Corporation 4-7 GPIB-1014 User Manual
Data In Register (DIR)
VMEbus Address: Base Address + 111 (hex)
Attributes: Read Only, Internal to TLC
7 654 3210
DI7 DI6 DI5 DI4 DI3 DI2 DI1 DI0
R
The Data In Register (DIR) is used to move data from the GPIB to the computer when the
interface is a Listener. The GPIB Ready For Data (RFD) message is held false until the byte is
removed from the DIR, either by a DMA transfer to the VMEbus memory or by an I/O read from
a VMEbus master.
DI0 is the least significant bit of the data byte and corresponds to GPIB DI01. DI7 is the most
significant bit of the data byte and corresponds to GPIB DI08.
Bit Mnemonic Description
7-0r DI[7-0] Data In Bits 7 through 0