Universal 48-Point I/O
with Interruptible Event Sense
Supports 48 digital I/O lines
Each line is capable of:
• Bidirectional operation
• Input, Output or Output with Read back
• 12mA Sink Current
Generates an interrupt on signal change-of-state:
• Supports 24 event sense lines
• Software selectable edge polarity for each line
• Software enabled interrupt for each line
• Change-of-state latched for each line
Write-protection mask register for each 8-bit port
Compatible with industry standard I/O racks
Fused +5V logic supply for I/O modules
8- or 16-bit PC/104 interface
+5 volt only operation
RoHS compliant product
Extended temperature range: -40oC to +85oC
The PCM-UIO48A-G is a highly-versatile PC/104 input/
output module providing 48 lines of digital I/O. The major
feature of this card is its ability to monitor 24 lines for both
rising and falling digital edge transitions, latch them and
then interrupt the host processor notifying that a change-
of-input status has occurred. This is an efficient way of sig-
naling the CPU of real-time events without the burden of
polling the digital I/O points.
This PC/104 module is also compatible with industry
standard isolated I/O signal conditioning modules from
Opto-22, Gordos, and others. This module is RoHS-
PC/104 Interface - The PCM-UIO48A-G is a PC/104
compatible stackthrough card which is I/O port mapped on
any even 16-byte boundary.
Parallel I/O Controller - WinSystems has designed
a WS16C48 Universal I/O controller ASIC to support
the various input/output and interrupt configurations. The
WS16C48 supports 48 digital I/O lines addressed through
six contiguous registers. A six-bit Write Mask register
allows the user to disable Writes on a byte basis to config-
ure the group as a “Read Only” port.
Each I/O line is individually programmable for input, out-
put, or output with Read back operation. The input lines are
connected so the current status of its output port can be
read from the corresponding input port (Read back).
If the port is used as input only, then the corresponding
output port bit must be cleared. Each output channel is
latched and has an open collector driver (with a pull-up
resistor) capable of sinking 12mA of current. This allows
direct control of up to 48 opto-isolated signal conditioning
modules to a single card for high density I/O support.
Event Sense Operation - Each WS16C48 ASIC supports
24 event sense lines to generate an interrupt when an event
occurs. This means that 24 lines of the PCM-UIO48A-G
can sense a positive or negative transition on the input.
Transition polarity is programmable and enabled on a bit-
by-bit basis. Each lines’ transition is latched by the event
so that even short duration pulses will be recognized. An
interrupt ID register is maintained for each line for writing
more efficient Interrupt Service Routines.
Interrupts - The PCM-UIO48A-G can generate a system
interrupt request which can be routed via jumper to IRQ
channels 2 - 7 on the 8-bit or the additional five interrupt
channel inputs on the 16-bit version.
I/O Connectors - The signals from the WS16C48
are wired to two 50-pin connectors, J1 and J2. Each
connector supports 24 data lines which are alternated
with 24 ground lines for reduced noise and crosstalk.
Also, each connector has a 1A fuse on the +5 volt source
to supply logic power for I/O module rack.