ICS PCI-16ISO, User Manual

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Introduction 1-1
Chapter 1
Introduction
The PCI-16ISO provides sixteen optically isolated inputs to allow the
monitoring of offboard switch closures and relays, or for any other general
purpose monitoring. The PCI-16ISO
is PCI 2.1 bus compliant. Addressing,
data, and control signals are all TTL compatible.
The PCI-16ISO provides two parallel input ports. Port A and B are interfaced
to optically isolated inputs. Assuming an I/O address of 300 Hex the following
table shows the port addresses.
Features
n
Two 8-bit input ports
n
DB-37 female connector
n
Multiple adapters can reside in same computer
n
All address, data, and control signals are TTL compatible
Ports A and B are 8-bit input ports connected to optically isolated input
sensors. Each sensor can be used to interface a voltage input and then sense
whether the voltage is on or off. Each sensor is isolated with respect to a
common ground from every other sensor and also isolated with respect to the
host PC ground. This means that signals, such as low-level AC voltage, motor
servo voltage, and control relay signals, can be ‘sensed’ or read by the PC
without the risk of damage due to ground loops or ground faults.
Each sensor input pair has a current limiting resistor that is used to limit the
input current to the opto-isolator. The opto-isolator has two ‘back-to-back’
diodes internally. This allows AC or DC signals to be sensed regardless of
polarity. When the signal is high enough to cause the opto-isolator to turn on,
the output of the opto-isolator goes low (0 volts) and the port bit is read as a
low logic level (binary 0) by the PC. When the input signal is too low to turn on
the opto-isolator, the output goes high and the port bit is read by the PC as a
high logic level (binary 1).
Base Address Hex Decimal Mode
Port A Address 300 768 Input Port
Port B Address 301 769 Input Port