Configuration and Installation
Section Two
GPIB-LPT User Manual
2-2
© National Instruments Corporation
Configuration
When installing the GPIB-LPT you must determine which IBM PC parallel port adapter the
GPIB-LPT board will respond to and select the appropriate base address and interrupt level. The
GPIB-LPT can be configured to one of three base addresses:
•
3BC Monochrome adapter
•
378/37C Parallel Port 1
•
278/27C Parallel Port 2
It is shipped from the factory set to 278/27C. The GPIB-LPT needs to be reconfigured if there is
another device (such as a printer adapter card or a built-in parallel port) at the same address.
DOS has reserved device names for the parallel ports it finds in the system: LPT1 or PRN, LPT2,
and LPT3. The parallel port adapters are named in the order in which they are found. Whenever
the computer is turned on, it searches all three parallel port addresses for installed adapters. It first
searches 3BC (LPT1), then 378 (LPT2), then 278 (LPT3). If only one device is installed, that
device is named LPT1 regardless of what its I/O address is. If there is more than one parallel
device installed, the first one found is assigned LPT1, the second one found is assigned LPT2, and
so on.
The GPIB-LPT may need to be reconfigured if its interrupt level conflicts with another device. If
the base I/O address of the GPIB-LPT does not conflict with any other device in your computer
and the GPIB-LPT still does not work with your software package, reconfigure the GPIB-LPT to a
different interrupt level.
Table 2-1 shows the standard base I/O address and interrupt level for each parallel port.
Table 2-1. IBM PC Parallel Port Adapters
Name of Port
Base I/O Address (hex)
Interrupt Level
Monochrome Display
3BC
7
and Printer Adapter
Parallel Port 1
378 or 37C
7
Parallel Port 2
278 or 27C
5
The GPIB-LPT is shipped from the factory configured to operate as Parallel Port 2 (base I/O
address 278 or 27C). If your PC already has a device responding to Parallel Port 2, it is necessary
to reconfigure the GPIB-LPT board to another parallel port by changing the base I/O address and
interrupt level.