User manual

PCI-1757UP User Manual 2
Chapter 1 General Information
1.1 Introduction
PCI-1757UP is a 24-bit DI/O card with PCI bus. It provides you with 24
bits of parallel digital input/output, and emulates mode 0 of the 8255 PPI
chip, but the buffered circuits offer a higher driving capability than the
8255.
The card emulates one 8255 PPI chips to provide 24 DI/O bits. The I/O
bits are divided into three 8-bit I/O ports: A0, B0 and C0. You can config-
ure each port as either input or output via software. The dual interrupt
handling capability provides users the flexibility to generate interrupts to
a PC. A pin in the connector can output a digital signal simultaneously
with the card's generating an interrupt.
This card uses a DB 25-pin connector for easy and reliable connections to
field devices.
One feature gives PCI-1757UP a practical advantage in an industrial set-
ting. When the system is hot reset (the power is not turned off) the PCI-
1757UP retains the last I/O port settings and output values if the user has
set jumper JP1 to enable this feature. Otherwise, port settings and output
values reset to their safe default state, or to the state determined by other
jumper settings.
1.2 Numbering Convention
All numbers given in this manual are in decimal format unless specifi-
cally noted otherwise. In particular, where a register address is given as
(Base + 32), the decimal number "32" should be added to the base value.