Allen Bradley is the leader in PLCs.  The SLC 500 series is the most commonly used series.  There are several things to keep in mind when creating your system.  There are many different variations you can use depending on your needs.

Benefits  Powerful, yet affordable - SLC 500 programmable controllers provide
excellent value with extensive capabilities to address a broad range of
applications including material handling, HVAC control, high speed
assembly operations, small process control, simple motion control, and
SCADA.
􀁹 Modularity - Modular processes, power supplies, I/O, memory options,
and communication interfaces allow for a configurable and expandable
system. Configure your system for the number of I/O, the amount of
memory, and the communication networks needed. Later, you can
expand the system by adding I/O, memory, or communication
interfaces.
􀁹 Advanced instruction set - Includes indirect addressing, high level
math capability, and a compute instruction.
􀁹 Communication network versatility - Choose from on-board
Ethernet, DH+, or DH-485, as well as options for ControlNet,
DeviceNet, or Remote I/O communications.
􀁹 Broad selection of I/O - Select from over 60 modules to control
discrete, analog, and temperature signals. Third-party specialty
modules are also available from Encompass partners to customize
control solutions for your application needs.
􀁹 Industrially hardened product - Designed to withstand the vibrations,
thermal extremes, and electrical noise associated with harsh industrial
environments.
􀁹 Windows programming software - RSLogix 500 programming
software maximizes productivity by simplifying program development
and troubleshooting.
Allen-Bradley, ControlLogix, PLC-5, RSLinx and VersaView are registered trademarks of Rockwell
Automation.
Block I/O, CompactLogix, Flex, FlexLogix, MicroLogix, PanelView, RSLogix, RSNetWorx and SLC are
trademarks of Rockwell Automation.
ControlNet is a trademark of ControlNet International, Ltd.
DeviceNet is a trademark of ODVA (Open DeviceNet Vendor Association)
Ethernet is a trademark of Xerox Corp.
Microsoft, Windows, and Windows 98 are registered trademarks of Microsoft Corp.
Windows NT is a trademark of Microsoft Corp.
SLC 500 Systems Selection Guide 3
1747-SG001B-EN-P — March 2005
SLC™ 500 System Overview
The Allen-Bradley SLC 500 is a small chassis-based family of
programmable controllers, discrete, analog, and specialty I/O, and
peripheral devices. The SLC 500 family delivers power and flexibility with
a wide range of communication configurations, features, and memory
options. The RSLogix 500 ladder logic programming package provides
flexible editors, point-and-click I/O configuration, and a powerful
database editor, as well as diagnostic and troubleshooting tools to help
you save project development time and maximize productivity.
Typical Systems With up to 64K of configurable data/program memory available and over
60 types of I/O modules, as well as a choice of networking options, the
SLC system provides a powerful solution for stand-alone or distributed
industrial control.
Table of Contents

At minimum, a modular hardware SLC 500 control system consists of a
processor module and I/O modules in a single 1746 chassis with a
power supply.
Power Supply
Processor
I/O Modules
You can configure a system with one, two, or three local chassis, for a
maximum total of 30 local I/O or communication modules. You connect
multiple local chassis together with chassis interconnect cables to
extend the backplane signal lines from one chassis to another.
Power Supply
Processor
I/O Modules
Power Supply
I/O Modules
I/O Modules
Chassis Interconnect Cable
Chassis Interconnect Cable
Power Supply
SLC 500 Systems Selection Guide 5
1747-SG001B-EN-P — March 2005
Distributed Systems
More complex systems can utilize:
􀁹 distributed I/O
􀁹 multiple controllers joined across networks
􀁹 I/O in multiple platforms that are distributed in many locations and
connected over multiple I/O links
Choose the processor module with the on-board communication ports
you need. You optionally add modules to provide additional
communication ports for the processor. For I/O in locations remote from
the processor, you can choose between a ControlNet, DeviceNet, or
Univeral I/O link. A communication interface module is required in both
the local and remote chassis.
Depending upon the communication ports available on your particular
SLC control system, you can select operator interfaces that are
compatible.
Computers
Processors
HMIs
Internet Browser
DH-485
EtherNet/IP
DH+
DF1
ControlNet
DeviceNet
1746 Chassis Backplane
Communication
interface modules in
the I/O chassis
where the SLC
processor resides.
1746 I/O modules in
the I/O chassis local
to the SLC processor.
A maximum of
960 I/O.
ControlNet Link
DeviceNet Link
Universal Remote I/O Link
Remote I/O
Modules
SLC Processor
Module
SLC 500 Systems Selection Guide 6
1747-SG001B-EN-P — March 2005
Laying Out the System
Lay out the system by determining the amount of I/O necessary, the
network configurations, and the placement of components in each
location. Decide at this time whether each chassis will have it’s own
controller or a networked solution.
SLC 500 processors are available with a large range of memory sizes (1K
through 64K) and can control up to 4096 input and 4096 output signals.
All modular processors except the SLC 5/01 are capable of controlling
remotely located I/O. By adding an I/O scanner module, you can use
these processors to control/monitor these remotely located I/O across
ControlNet, DeviceNet, and Universal Remote I/O links.
SLC 500 processors are single-slot modules that you place into the leftmost
slot of a 1746 I/O chassis. For I/O in a location remote from the
processor, the I/O adapter is a single-slot module that you place in the
left-most slot of the I/O chassis. SLC 500 modular systems provide
separate power supplies which must be mounted directly on the left end
of the 1746 I/O chassis.
The 1746 I/O chassis are designed for back-panel mounting and
available in sizes of 4, 7, 10, or 13 module slots. The 1746 I/O modules
are available in densities up to a maximum of 32 channels per module.
Communications
Evaluate what communications need to occur. Knowing your
communications requirements will help you determine which processor
and which communications devices your application might require.
An SLC processor communicates across the 1746 backplane to 1746 I/O
modules in the same chassis in which the processor resides. Various
models of SLC processors have various on-board ports for
communication with other processors or computers. Also, separate
modules are available to provide additional communication ports for
communication with other processors, computers, and remotely located I/O.
Each processor has one or two built-in ports for either EtherNet/IP, DH+,
DH-485, or RS-232 (DF1, ASCII, or DH-485 protocol) communication.
In addition to the on-board ports available with SLC processors, you
have the option of providing another communication port for an SLC
processor by adding a communication module.
Adapter modules for 1746 I/O are available for ControlNet and Universal
Remote I/O links. An I/O adapter module in a chassis with I/O modules
interfaces the I/O modules with the I/O link for communication with a
scanner port for a processor at another location.
SLC 500 Systems Selection Guide 7
1747-SG001B-EN-P — March 2005
Evaluate what communications need to occur. Knowing your
communications requirements will help you determine which processor
and which communications devices your application might require.
An SLC processor communicates across the 1746 backplane to 1746 I/O
modules in the same chassis in which the processor resides. Various
models of SLC processors have various on-board ports for
communication with other processors or computers. Also, separate
modules are available to provide additional communication ports for
communication with other processors, computers, and remotely located I/O.
Each processor has one or two built-in ports for either EtherNet/IP, DH+,
DH-485, or RS-232 (DF1, ASCII, or DH-485 protocol) communication.
In addition to the on-board ports available with SLC processors, you
have the option of providing another communication port for an SLC
processor by adding a communication module.
Adapter modules for 1746 I/O are available for ControlNet and Universal
Remote I/O links. An I/O adapter module in a chassis with I/O modules
interfaces the I/O modules with the I/O link for communication with a
scanner port for a processor at another location.
SLC 500 Systems Selection Guide 8
1747-SG001B-EN-P — March 2005
SLC 500 Common
Specifications
The following specifications apply to all SLC 500 modular components
unless noted.
Description
Temperature
Humidity
Vibration
Shock
Free Fall (drop test)
Noise Immunity
Electromagnetic Compatibility
Safety
Certification
(when product or packaging is marked)
Specification
Operating: 0…60 °C (32…140 °F)
Storage: -40…85 °C (-40…185 °F)
5…95% without condensation
Operating: 1.0 g at 5…2000 Hz
Non-operating: 2.5 g at 5…2000 Hz
Operating: 30 g (3 pulses, 11 ms) - for all modules except relay contact
Operating: 10 g (3 pulses, 11 ms) - for relay contact modules 1746-OWx and 1746-IOx combo
Non-operating: 50 g, 3 pulses, 11 ms
Portable, 2.268 kg (5 lbs) or less at 0.762 m (30 in.), six drops
Portable, 2.268 kg (5 lbs) or less at 0.1016 m (4 in.), three flat drops
NEMA Standard ICS 2-230
Showering ARC: 1.5 kV (Industry Standard - NEMA ICS 2-230/NEMA ICS 3-304)
Surge Withstand Capability: 3 kV (Industry Standard - IEEE Std. 472-1974/ANSI C37.90/90A-1974)
Fast Transient Burst (impulse): 2 kV for 1746 power supplies, 1 kV for 1746-I/O and communication lines over 10 m
(32.48 ft), 5 ms rise time
Electrostatic Discharge (ESD): 15 kV, 100 pF/1.5 kΩ model
Radiated Electromagnetic Susceptibility: 5 W walkie-talkie at 464.5 MHz and 153.05 MHz
Dielectric Withstand: 1500V ac (Industry Standard - UL 508, CSA C22.2 No. 142)
Isolation between Communication Circuits: 500V dc
Isolation between Backplane and I/O: 1500V ac
Flammability and Electrical Ignition: UL94V-0

Selecting SLC 500 I/O Modules Step 1 - Select:
Digital I/O modules, analog I/O modules, and specialty temperature,
counting, process control, and BASIC language modules are available to
help you create a custom solution for your application.
1746 Digital I/O
Modules
Digital I/O modules are available with 4, 8, 16, or 32 channels and in a
wide variety of I/O voltages (including AC, DC, and TTL). Combination
modules with 2 inputs/2 outputs, 4 inputs/4 outputs, and
6 inputs/6 outputs are also available.
Terminals on the 4-, 8-, 12-, and 16-channel modules have self-lifting
pressure plates that accept two 14 AWG (2 mm2) wires. LED indicators
on the front of each module display the status of each I/O point.
32-channel I/O modules are equipped with a 40-pin, MIL-C-83503 type
header and a removable wiring connector (1746-N3). The connector can
be assembled with the wire type and length of your choice.
Output modules are available with solid-state AC, solid-state DC, and
relay contact type outputs. High current solid-state output modules,
Catalog No. 1746-OBP16, -OVP16, and -OAP12, have fused commons
with a blown fuse LED. The 1746-OB16E, -OB6EI, and -OB32E modules
provide electronic protection from short circuit and overload conditions.
Wiring of 16- and 32-channel modules can also be accomplished with a
Catalog 1492 Interface module and pre-wired cable. All 16-channel I/O
modules and Catalog Numbers 1746-OX8, -OBP8, -OAP12, 1746-IO12
are equipped with color-coded removable terminal blocks.
􀁹 I/O modules - available in a variety of
densities and voltage options. Some
modules have diagnostic features,
individually isolated inputs/outputs
or electronic protection.
􀁹 Consider interface modules (IFMs)
or pre-wired cables

Cat. No.
1746-IB8
1746-IB16
1746-IB32
1746-ITB16
1746-IC16
1746-IH16
1746-IV8
1746-IV16
1746-IV32
1746-ITV16
1746-IG16􀀷
1746-OB6EI
1746-OB8
1746-OB16
1746-OB16E‡
1746-OB32
1746-OB32E
1746-OBP8‡
1746-OBP16􀀹
1746-OV8
1746-OV16
1746-OV32
1746-OVP16􀀹
1746-OG16􀀷
1746-IA4
1746-IA8
1746-IA16
1746-IM4
1746-IM8
1746-IM16
1746-OA8
1746-OA16
1746-OAP12􀀹
1746-IN16
1746-OW4􀀹
1746-OW8􀀹
1746-OW16􀀹
1746-OX8􀀹
1746-IO4􀀹
1746-IO8􀀹
1746-IO12􀀹
1746-IO12DC‡

1746 Analog I/O
Modules
Analog I/O modules feature user-selectable voltage or current inputs,
backplane isolation, removable terminal blocks, and diagnostic feedback.
The 1746-NI4, -NIO4I, and -NIO4V input channels are filtered to reject
high frequency noise and provide 14- to 16-bit (range-dependent)
resolution.
All 4-channel analog output modules provide 14-bit resolution and a
2.5 ms conversion rate.
The 1746-FIO4I and -FIO4V have less input filtering and can sense more
rapidly changing inputs. However, their input resolution is only 12-bit.
Because the input filter on the 1746-FIO4I or -FIO4V may pass more
electrical noise, you should thoroughly ground and shield the input
transducer, its power supply, and cables.
The 1746-NI8 provides high accuracy and fast analog signal conversion.
The 1746-NI8, -NI16I and -NI16V are high density analog input modules
that are software configurable.
The 1746-NO8I (current output) and 1746-NO8V (voltage output) are high
density, analog output modules that provide 8 individually configurable
output channels with 16-bit resolution.
Combination I/O Modules

Cat. No.
1746-NI4
1746-NI8
1746-NI16I􀀹
1746-NI16V􀀹
1746-NIO4I
1746-NIO4V
1746-FIO4I
1746-FIO4V
1746-NO4I
1746-NO4V
1746-NO8I
1746-NO8V
Analog I/O Module Overview
􀀹 The 1746-NO4I and 1746-NO4V analog output modules have connections for user-supplied 24V dc power supplies. When external 24V dc power is used, the module only draws 5V dc
current from the SLC backplane. If an external 24V dc power supply is required, the tolerance must be 24V ±10% (26.6…26.
4V dc).

The user power supplies for SLC 500 modular systems,
1746-P1, -P2, -P5, and -P6 do not meet this specification.
SLC modular chassis provide flexibility in system configuration. Four
chassis sizes are available to suit your application needs. Choose from
4-slot, 7-slot, 10-slot, and 13-slot chassis based on your modular
hardware component requirements. The SLC 1746 modular chassis
houses the processor or I/O adapter module and the I/O modules.
Each chassis requires its own power supply, which mounts on the left
side of the chassis. A maximum of 3 chassis can be connected with
chassis interconnect cables (not included). If an interconnect cable is
required, select a chassis interconnect cable from the following table.
Chassis and Cable Descriptions
Cat. No.
1746-A4
1746-A7
1746-A10
1746-A13
1746-C7
1746-C9
1746-C16
Descriptions:
4-Slot Chassis
7-Slot Chassis
10-Slot Chassis
13-Slot Chassis
Chassis Interconnect Cable – ribbon cable used when linking
modular style chassis up to 152.4 mm (6 in) apart in an enclosure.
Chassis Interconnect Cable – used when linking modular style
chassis from 152.4 mm (6 in) up to 914.4 mm (36 in) apart in an
enclosure.
Chassis Interconnect Cable – used when linking modular style
chassis from 0.914 m (36 in) up to 1.27 m (50 in) apart in an
enclosure.

When configuring a modular system, you must have a power supply for
each chassis. Careful system configuration will result in optimal system
performance. Excessive loading of the power supply outputs can cause
a power supply shutdown or premature failure.
See the power supply selection example in the next section and use the
blank worksheet provided at the end of this guide to determine which
power supply is appropriate for your system. You need one worksheet
for each chassis.
TIP: Consider future system expansion when choosing power supplies.
The SLC system features three AC power supplies and four DC power
supplies. The power supply mounts on the left side of the chassis with
two screws. For AC power supplies, 120/240 volt selection is made by
placing the jumper to match the input voltage. SLC power supplies have
an LED that illuminates when the power supply is functioning properly.
Power supplies are designed to withstand brief power losses. Power loss
does not affect system operation for a period between 20 milliseconds
and 3 seconds, depending on the load.