Changing Board and Device Characteristics
Appendix B
GPIB-PCII/IIA for Graphics
B-2
© National Instruments Corp.
Characteristics of Each GPIB-PCII/IIA
Each GPIB-PCII/IIA board has the following characteristics:
•
A symbolic name (either
GPIB0
or
GPIB1
).
•
A GPIB primary or secondary address.
•
A computer I/O address.
•
A GPIB-PC mode (either PCII or PCIIA).
•
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, highest-speed, or normal timing when transmitting data to a
device. With normal timing, there is a delay of at least 2
µ
s 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 ns, and with highest-speed
timing, it is decreased to about 350 ns. The default setting of 2
µ
s is
recommended, as some devices cannot communicate at higher speeds.
Default Configurations
The default configurations of the software were set at the factory. For example, the
default device names of the 32 GPIB devices are
DEV1
through
DEV32
, but your
application manual may instruct you to assign a more descriptive name to a
particular device, such as
SCANNER
.
