GE 8752-CA-NS Universal Node Services Carrier
GENERAL
PAC8000 I/O is a completely modular I/O 
solution for both general purpose and 
hazardous area applications. Based upon 
a carrier system that supports a range of 
modules, it offers a wide variety of I/O functions, including AC mains and intrinsic safety 
signals - even within the same node. It has an 
“open” architecture that allows communication with a variety of different field-buses by 
selecting the appropriate type of Bus Interface Module (BIM) or Controller.
I/O Modules
I/O modules transfer signals to and from field 
instruments. Input modules receive signals 
from transmitters and sensors and convert 
them into a digital form for presentation to 
the BIM or Controller. Output modules receive 
commands from the BIM or Controller and 
transfer them to actuators. A wide range 
of modules is available, including types for 
low-level instrumentation, AC mains and 
intrinsically safe signals. I/O modules can 
have 4, 8, 16, or 32 field channels.
Field terminals
Field terminals provide the interface between 
the I/O modules and the field wiring. They 
include fusing and loop disconnect as options. 
A mechanical keying system helps prevent 
an I/O module from being connected to the 
wrong type of field terminal. Field terminals 
mount onto the module carrier, one to each 
I/O module. They are clamped firmly by the 
I/O module to form an electrical and mechanical assembly of high integrity. They may be 
replaced in service without removing carriers 
or disturbing the operation of other modules.
Carriers
Carriers form PAC8000’s physical and electrical backbone by providing a mounting 
onto a flat panel or T- or G-section DIN rail. 
They support and interconnect the BIM or 
Controller, power supplies, I/O modules and 
field terminals, and carry the address, data 
and power lines of the internal Railbus. 
They provide a termination points for the 
LAN and field wiring cable screens and can 
also distribute bussed field power to the I/O 
modules. I/O module carriers are available to 
support four or eight I/O modules.
Power supplies
Good power management lies at the heart 
of a true distributed I/O system. 8000 power 
supplies accept locally available unregulated 
power and provide a regulated supply for the 
BIM or Controller and I/O modules. Supply 
redundancy is supported.
Bus Interface Module (BIM)
The BIM provides a serial data connection 
to a host controller, which could be a distributed control system (DCS), a programmable 
logic controller (PLC), or a PC running a soft 
control package. A choice of BIMs allows you 
to accommodate the most popular fieldbus 
protocols. The BIM also uses a fast internal 
bus to pass data to, and obtain data from, 
the I/O modules. Only one BIM is required at 
each node to control up to 64 I/O modules.
Controllers
Controllers are an alternative to BIMs - and 
are used where distributed control is required, 
rather than distributed IO. A number of 
different Controllers are available which 
are suited to particular applications. The

Logic Controller runs applications based on 
IEC61131 languages, the Process Controller 
has a control package that uses DCS-style 
function blocks and the Hybrid Controller can 
run both application packages in a single unit. 
The SafetyNet Controller is SIL 2 compliant 
for emergency shut-down and fre and gas 
applications. The RTU Controller runs IEC61131 
application programmes and supports DNP3 
communication protocol.
“HART-ability”
The use of ‘smart’ instruments on process 
plants is growing but this investment is not 
always fully exploited. Whether it is for a new 
installation, or the upgrade of an existing 
one, we have solutions that provide the 
connections between the HART field instruments, the control systems and the asset 
management software. 
Specifically, the PAC8000 Process I/O system 
has been designed to be transparent to 
HART signals, thus allowing the host control 
software and any HART field instruments to 
communicate directly with each other.
In addition, PAC8000’s HART connection 
system provides on-line access from a PC to 
the HART field devices for monitoring device 
performance. HART devices may be selected 
for regular status monitoring and alerts can 
be issued if the status changes. The benefits 
from this approach are:
• Reduced commissioning time and cost
• Reduced process downtime through status 
monitoring
• Lower loop maintenance costs by using 
field device diagnostics
8000 in your system
Figure 1 shows two possible methods for 
linking the 8000 into a system. On the left is 
a host controller system that uses fieldbus as 
the main distribution medium. On the right 
is a section of a typical DCS/PLC informa tion network, with an operator station that 
uses a separate interface to the process 
fieldbus. The number of 8000 nodes that 
can be accommodated depends upon the 
addressing capability of the fieldbus in use. 
Each 8000 node can address 32 I/O modules 
which, depending upon the number of chan nels per module, can provide up to 512 I/O 
points at a single node! A node can consist 
of a mixture of analog and discrete modules 
and this gives maximum flexibility to the 
system designer. Where supported by the 
fieldbus, full HART pass-through is provided—
the 8000 appears “transparent”, allowing the 
host controller to access the HART capabili ties of field instruments.