70M-OSW1 Grayhill, Inc, 70M-OSW1 Datasheet - Page 21

• Manufacturer Part Number: 70M-OSW1
• Description: Opendac I/o System Low Cost Remote I/o System
• Manufacturer: Grayhill, Inc

System 50
APPLICATIONS
DIGITAL INPUTS/OUTPUTS
The 72-PMX-24D controller board mates with
any of our 8, 16, or 24 digital module racks. The
72-PMX-32D or 72-PMX-32AD controller
board mates with special rack part number
70GRCP32-HL which accepts up to 32 G5
analog or digital I/O modules. Connections are
made between the PC (or other type of host)
parallel port and the controller boards via a 50
pin flat ribbon cable. The cable can be up to 500
feet in length. The cable from the host is
connected to the first controller board on the
bus and then daisy chained to additional
controller boards. Up to 32 controller boards
with 16 module racks (or 16 controller boards
with 24 or 32 module racks) can be added
anywhere along the cable. The maximum
number of I/O per parallel port is 512.
NETWORK INTERFACES
Parallel Bus
FEATURES
• Each Board Controls Up to 24 or 32
• Scans 512 Digital I/O Points in
• Compatible With Parallel Controller
• DIP Switch Selectable Address
• Up to 32 Addressable Boards Over
• On-Board Terminating Resistors
• On-Board Communications
I/O Modules
Less Than 200 µSec.
Boards From Other Manufacturers
and Options
500 Feet
Watchdog Timer
3 5
Grayhill, Inc. • 561 Hillgrove Avenue • LaGrange, Illinois 60525-5997 • USA • Phone: [phone] • Fax: [phone] • www.grayhill.com
Stand Alone Control
Local Control & I/O
Distributed I/O
Remote I/O
SCADA
RTU
System 50
SPEED
The parallel bus is high speed. The host PC
can read or write eight digital I/O modules in
less than 3 microseconds which means that
512 digital I/O modules can be scanned in less
than 200 microseconds! Each group of eight
I/O modules are accessed through a separate
I/O port register on the host PC or controller.
In assembly language, an IN or OUT instruction
is used to read or write this information. In C
language, an inp or outp function call is used.
In BASIC, an INP or OUTP instruction is used.
WATCHDOG TIMER
Each controller board has an on-board
communications watchdog timer which
monitors communications between the host
and controller board. A timer value between
0.5 seconds and 12 seconds is selected for
each board. On power up, the timer begins
counting down. Whenever a message from
the host is received, the timer is restarted.
Should the timer time out, all of the output
modules being controlled by the board will be
set to one of four DIP switch selectable
conditions (ie. all off).
OTHER FEATURES
One of the control lines on the parallel bus is
called RESET. The RESET line can be used to
simultaneously turn off all of the output modules
being controlled by each of the boards on the
bus.
Three LEDs on the controller boards assist in
troubleshooting problems. They indicate when
power is being applied, when messages are
being received, and when the watchdog timer
has timed out.
THE 72-PC28 ADAPTER CARD
In applications where the host computer is a
PC, the 72-PC28 adapter card is an IBM PC/
XT/AT bus to parallel bus interface which
occupies a single half slot in the computer. The
bus ribbon cable plugs into it's 50-pin male
header connector. Each adapter card can
drive up to thirty two 72-PMX-24D controller
boards, sixteen 72-PMX-32D controller boards
or sixteen 72-PMX-32AD controller boards
over a total distance of 500 feet. Up to four 72-
PC28 adapter cards can be installed in one PC.
The base address for the card and wait states
are DIP switch selectable.
Each 72-PC28 includes a complete User's
Manual and a software setup/test utility
program. This program graphically shows you
dip switch, jumper and termination resistor
settings for the system configuration you
decided. You can then use the program to
configure and manipulate any I/O on the parallel
bus.
All controller boards are thoroughly tested
prior to shipment.