Software Installation and Configuration
Chapter 3
GPIB-PCIIB/MS-DOS
3-10
© National Instruments Corp.
•
A time limit imposed when executing certain functions. This time limit
ensures that transfers do not hang up the GPIB indefinitely.
•
A way to terminate I/O transmissions to and from the device. Some
devices require or append an EOS character, such as the ASCII line
feed character, to data strings. Others use the GPIB END message,
which is sent or received via the EOI signal line. Still others use both.
Some terminate messages only when a predetermined number of bytes
are sent or received.
Characteristics of Each GPIB-PCIIB Board
Each GPIB-PCIIB board has the following characteristics:
•
A symbolic name (such as
GPIB0
or
GPIB1
).
•
A GPIB primary and, possibly, a secondary address.
•
A computer I/O address.
•
The capability to be designated as the system controller of the devices
on its bus.
•
A time limit imposed when executing certain functions.
•
A way to terminate I/O transmissions to and from the board when
executing board calls, for example, by an EOS character, an END
message, and/or a byte count.
•
An interrupt line that the board uses, if any.
•
A DMA channel that the board uses, if any.
•
High-speed or normal timing when transmitting data to a device. With
normal timing, there is a delay of at least 2
µ
sec after the data is placed
on the GPIB before the Data Valid (DAV) line is asserted. With high-
speed timing, this delay is decreased to about 500 nsec. High-speed
timing is strongly recommended.
•
The ability to disable device unaddressing.