Chapter 4
Register Bit Descriptions
© National Instruments Corporation
4-7
GPIB-1014 User Manual
Data In Register (DIR)
VMEbus Address:
Base A 111 (hex)
Attributes:
Read Only, Internal to TLC
7
6
5
4
3
2
1
0
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