Installation Instructions
Cat. No. 1771-A2BSS and 1771-A3B1SS
What This Document Contains
To the Installer
Prepare for Installation
I/O-group-label set (cat. no. 1771-XB)
This publication covers the cat. no. 1771-A2BSS special 8-slot, and
the cat. no. 1771-A3B1SS special 12-slot stainless steel versions of
the universal 1771 I/O chassis.
To install an I/O chassis you See page
prepare for installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
allow sufficient mounting space . . . . . . . . . . . . . . . . . . . . . . 2
mount the I/O chassis and ground bus . . . . . . . . . . . . . . . . . 4
ground the chassis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
set the power supply configuration jumper . . . . . . . . . . . . . . . 8
set the switches on the backplane assembly . . . . . . . . . . . . . 9
provide power to the I/O chassis . . . . . . . . . . . . . . . . . . . . . 9
install I/O modules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Make sure you have these items:
Hardware kit (cat. no. 1771-RK)
plastic keying bands
18 – 1771-A2BSS
27 – 1771-A3B1SS
1 star washer
1 cup washer
4 flat washers
2 #10–32 nuts
with captive lock washers
10
Documentation
(if you are installing I/O modules or power supplies)
I/O Module
Cat. No. 1771-
xxx
User
Power Supply
Cat. No. 1771-Px
Installation Data
Output Module
Cat. No. 1771-
Installation Data
Manual
Power Supply Modules
Cat. No. 1771-
Installation Data
xx
xx
Power Supply Chassis
Cat. No. 1771-
xxx
Installation Data
for your:
• programmable controller or I/O adapter module
• external power supply and/or power supply chassis
(if you are using external power supplies)
• communication modules and/or I/O modules
• power-supply modules
Publication 1771–5.60 – May 1999
Universal I/O Chassis2
13082
Allow Sufficient Mounting Space
B
153mm
(6”)
For these mounting dimensions See page
I/O chassis 3
I/O chassis with external power supply 3
Important: Make sure you meet these minimum spacing
requirements.
C
102mm
(4”)
51mm
E
(2”)
wiring duct
E
51mm (2”)
D
153mm
(6”)
A
102mm
(4”)
102mm
(4”)
C
D
D
Minimum
A
is 102mm (4 inches).
Minimum vertical separation between major components is 153mm (6 inches).
B
Minimum horizontal separation between major components is 102mm
C
(4 inches).
Minimum vertical distance between a major component and the top or
D
bottom of an enclosure is 153mm (6 inches).
Minimum distance between major components and wiring ducts or terminal
E
strips is 51mm (2 inches).
153mm (6”)
distance between a major component and the sides of an enclosure
wiring duct
Publication
1771–5.60 – May 1999
1771-A2B
SS
1771-A2B
12451-
1771-A3B1SS
I/O Chassis Mounting Dimensions
use 1/4-20 (M6 x 10)
mounting bolts (four places)
1
193mm
(7.60”)
315mm
(12.41”)
Universal I/O Chassis 3
464mm
(18.25”)
337mm
(13.25”)
12-slot 1771-A3B1SS
8–slot 1771–A2BSS
254mm
(10”)
power
SS
1771-A3B1SS
You can mount 1771-P1, -P2, -P7 and
-PS7 power supplies on the left side
plate of the I/O chassis, or up to 5
cable-feet from the I/O chassis.
connector
grounding stud
171mm
(6.75”)
483mm
(19.01”)
356mm
(14.01”)
8–slot 1771–A2BSS
12-slot 1771-A3B1SS
I/O Chassis with External Power Supply Mounting Dimensions
use 1/4-20 (M6 x 10)
mounting bolts (four places)
315mm
(12.41”)
1771-P1
1771-P2
1771-P7
1771-PS7
Power Supply
464mm
(18.25”)
337mm
(13.25”)
12-slot 1771-A3B1SS
8–slot 1771–A2BSS
254mm
(10”)
grounding
stud
91mm
(3.6”)
483mm
(19.01”)
356mm
(14.01”)
Publication
8–slot 1771–A2BSS
12-slot 1771-A3B1SS
I
1771–5.60 – May 1999
Universal I/O Chassis4
Mount the I/O Chassis and Ground Bus
If you have this I/O chassis Type of mount
1771-A2BSS panel mount (rear mount)
1771-A3B1SS panel mount (rear mount)
Each enclosure must contain a central ground bus. The ground bus
is the common connection for each chassis within the enclosure and
the enclosure itself. Use either bolts or welded studs to mount the
I/O chassis and central ground bus. If you are mounting a chassis to
the back panel of an enclosure, use 1/4-20 (M6 x 10) mounting bolts.
Stud Mounting of the Back-panel to the Back Wall of the Enclousure Bolt Mounting of a Ground Bus or Chassis to the Back-panel
scrape
nut
back-panel
paint on panel
star washer
wall of enclosure
back
welded
stud
Use
a wire brush to remove
paint from threads to
provide a ground connection.
ground bus or
mounting bracket
ground lug
nut
scrape
back-panel
tapped hole
paint on panel
star washer
flat washer
flat washer
bolt
17664
star washer
Stud Mounting of a Ground Bus or Chassis to the Back-panel
back wall of enclosure
mounting bracket
or ground bus
ground lug
nut
flat
washer
star washer
scrape
paint from threads
flat washer
scrape
paint from mounting
bracket or ground bus
ATTENTION: If the mounting brackets of a chassis
do not lay flat before the nuts are tightened, use
!
additional washers as shims so that the chassis will not
be warped by tightening the nuts. Warping a chassis
could damage the backplane and cause poor
connections.
17665
welded stud
17666
Publication
1771–5.60 – May 1999
Universal I/O Chassis 5
mo
Ground Your I/O Chassis
te I/O Systems
Re
To properly ground your I/O chassis See page
verify that your system-design plans are using the correct
system grounding configuration . . . . . . . . . . . . . . . . . . . . . .
5
ground the chassis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
connect equipment grounding conductors . . . . . . . . . . . . . . . 7
connect a ground bus to the grounding electrode system . . . . 7
ground shielded cables . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8
Verify Grounding Configuration
enclosure
ground bus
grounding electrode conductor
To
grounding
electrode
system
I/O chassis
grounding stud
Extended-Local I/O Systems
enclosure enclosure
ground
bus
T
o
grounding
electrode
system
(single
point only)
extended local I/O cables
ground bus
19938
I/O chassis
grounding
stud
Publication
1771–5.60 – May 1999
Universal I/O Chassis6
When you connect grounding conductors to the
Ground the Chassis
This I/O chassis Has grounding stud(s) located
1771-A2BSS
1771-A3B1SS
ATTENTION: To prevent ground loops from
occurring, use only one grounding stud when
grounding your equipment.
Important: Use the following information, along with the
installation manual for your programmable controller to
ground the I/O chassis and your I/O modules.
Chassis Ground Single-point Grounding
I/O chassis
grounding stud, place a star washer under the first lug, then
place a nut with captive lock washer on top of each ground lug.
grounding
stud
ground lug
nut with captive washer
star washer
ground lug
I/O chassis side plate
1
nut with captive washer
ATTENTION: Use single-point grounding for
extended-local I/O systems. The systems must be
grounded properly for proper performance.
1
Use
the cup washer if crimp-on lugs are not used.
#10
thread-forming screw
external-tooth washers
19923
Publication
1771–5.60 – May 1999
Universal I/O Chassis 7
W
Connect Equipment Grounding Conductor
Connecting Equipment Ground Conductor to a Ground Bus
ground bus
mounting
ground bus
equipment
grounding
conductors
bolt
■
use
2.54cm (1in.) copper braid or 8 AWG copper wire to connect
ground
lug
star washer
tapped hole
Grounding electrode conductor
to grounding electrode system
each chassis, the enclosure and a central ground bus mounted
on the back-panel
■
use a steel enclosure to guard against electromagnetic
interference (EMI)
■
make sure the enclosure door viewing window is a laminated
screen or a conductive optical substrate (to block EMI)
■
install a bonding wire for electrical contact between the door and
the enclosure; do not rely on the hinge
13271
Connecting Equipment Ground Connector to an Enclosure
nut
ground lug
enclosure wall
star washer
scrape
equipment
grounding
conductor
star washer
paint from
bolt
panel
10020
Important:
Do
not lay one ground lug directly on top of the other; this
type of connection can become loose due to compression
of the metal lugs.
Place the first lug between a star washer and a nut with a
captive star washer
.
After tightening the nut, place the second lug between the
first nut and a second nut with a captive star washer
.
Connect an equipment grounding conductor directly from each
chassis to an individual bolt on the ground bus.
For chassis with Connect the equipment grounding conductor using
a ground stud the grounding stud
no ground stud a mounting bolt
If the power supply has its own groundable chassis, do not connect
the GND terminal of the power supply. However, when you connect
power to a power supply without a groundable chassis (such as an ac
input power-supply module), you must also use 14 AWG copper
wire to connect its GND terminal to the ground stud or mounting
bolt connected to the ground bus.
Connect Ground Bus to Grounding-Electrode System
The grounding-electrode system is at earth-ground potential and is
the central ground for all electrical equipment and ac power within
any facility. Use a grounding-electrode conductor to connect the
ground bus to the grounding-electrode system. Use at minimum 8
AWG copper wire for the grounding-electrode conductor to guard
against EMI. The National Electrical Code specifies safety
requirements for the grounding-electrode conductor.
Publication
1771–5.60 – May 1999
Universal I/O Chassis8
o
N
Y
Ground Shielded Cables
Certain connections require shielded cables to help reduce the effects
of electrical noise coupling. Ground each shield at one end only. A
shield grounded at both ends forms a ground loop which could cause
faulty PLC-5 processor operation.
Ground each shield at the end specified in the appropriate
publication for the product.
Avoid breaking shields at junction boxes. Many types of connectors
for shielded conductors are available from various manufacturers. If
you do break a shield at a junction box:
connect only category-2 conductors in the junction box
do not strip the shield back any further than necessary to make a
connection
connect the shields of the two cable segments to ensure continuity
along the entire length of the cable
For more information about grounding the chassis, see Industrial
Automation Wiring and Grounding Guidelines for Noise Immunity
(publication 1770-4.1).
Set the Power Supply Configuration Jumper
If you are using Set jumper t
a power-supply module or
a processor with an integral power supply
(1772-LSP, -LWP, -LXP or -LZP)
a power supply external to the I/O chassis
Set the power supply configuration jumper according to the power
supply you are using.
ATTENTION: If you do not properly configure the
power supply configuration jumper, the processor will
!
“Y” position
Y
“N” position
fail.
NY
Using
Power
Supply
Module in
the Chassis?
N
12620-I
Important: You cannot power a single I/O chassis with both a
power-supply module and an external power supply.
Publication
1771–5.60 – May 1999
Universal I/O Chassis 9
Set the Switches on the Backplane Assembly
I/O chassis
backplane switch assembly
Provide Power to the I/O Chassis
Use the installation manual for your programmable controller or
adapter module to set the switches.
ATTENTION: If you do not properly configure the
backplane switch assembly, various system failures
!
OFF ON
Your I/O chassis can receive power through:
may occur.
12345678
10807–I
• processors with integral power supplies that provide 2-4A
• power-supply modules that provide 3-8A
• external power supplies that provide 6.5-16A
(external power supplies are not designed for parallel operation)
Power-supply modules are designed for parallel operation. See your
power supply installation documentation for possible configurations.
Important: The 1772-LSP, -LWP, -LXP, and -LZP processor
modules already contain a power supply so you can
only parallel one additional power-supply module with
these processor modules.
ATTENTION: Do not connect an external power
supply and a power-supply module to the same I/O
!
If your I/O chassis is receiving power through Then
an external power supply or a power supply chassis continue with this section
power-supply modules go to page 10
chassis; they are incompatible.
Attaching a Power Supply to an I/O Chassis
The I/O chassis has two power connectors. You connect the external
power supply or power supply chassis (1771-PSC) to the I/O chassis
using these connectors and the appropriate power supply cables.
Publication
1771–5.60 – May 1999
Universal I/O Chassis10
Important: Use the installation data for your power supply or
power supply chassis to properly mount it to your I/O
chassis.
This I/O chassis Has power connectors located
If you mount a power supply to any I/O chassis, place the flat washers
provided between each mounting screw and the power supply mounting
bracket. If you do not use the flat washers, the mounting screw intrudes
into the I/O chassis and interferes with module insertion.
power supply mounting bracket
flat washer
I/O Chassis
mounting screw
Install Your I/O Modules
12447-I
The left-most slot of each chassis accepts either a processor module
or an I/O adapter module. The other slots in the chassis accept
communication modules, I/0 modules and power-supply modules.
PLC-5
Processor
1771-A2BSS
1771-A3B1SS
1771-A2BSS I/O chassis
I/O adapter module
1771–A2BSS I/O chassis
12453-I
locking-bar pins
front of chassis
communication cable
I/O modules
11865
To insert a module:
1. Pull the locking-bar pins to release the locking bar and swing up.
2. Use the installation data/user manual for your module to:
a. position the keying bands in the backplane connectors to
correspond to the key slots on the module. This prevents
you from inserting the wrong module in this slot.
ATTENTION: Observe the following precautions when
inserting or removing keys:
!
• insert or remove keys with your fingers
• make sure that key placement is correct
Incorrect keying or the use of a tool can result in damage
to the backplane connector and possible system faults.
Publication
1771–5.60 – May 1999
Universal I/O Chassis 11
ying ban
I/O chassis
ke
ds
backplane
connector
Each I/O module is slotted in two places
at the rear edge of the circuit board.
These slots are intended to mate with the
plastic keys supplied with each chassis.
I/O
module
I/O chassis
backplane connector
Repeat for each module you install.
b. install the module.
Important: Firmly press the module into the chassis backplane
connector. The chassis locking bar will not close if
any modules are not seated properly.
3. Swing the chassis locking bar down into place to secure the
modules. Make sure the locking pins engage.
4. Apply the I/O group labels over the scored lines on the I/O
chassis locking bar as shown below. On each label, record the
I/O rack number, I/O group number and terminal numbering for
each module.
R
GG
00
00
07
07
10
10
17
17
placement
I/O
Group Label
A digital 8-point
GG
00
07
10
17
I/O module has its
terminals numbered:
00
07
10
17
00–07 (left slot)
10–17 (right slot)
or
A digital 32-point I/O module
in any slot has its terminals
numbered for two I/O groups.
1st I/O group – 00–07 and 10–17
2nd I/O group – 00–07 and 10–17
scored line
front of chassis
A digital 16-point
I/O module has its
terminals numbered:
00–07
and
10–17
locking bar
Examples:
2–slot addressing
(8-point I/O
modules)
1–slot addressing
(16-point I/O
modules)
1/2–slot addressing
(32-point I/O
modules)
R
GG
00
00
07
07
10
10
17
17
R
GG
00
00
07
07
10
10
17
17
R
GG
00
00
07
07
10
10
17
17
GG
00
00
07
07
10
10
17
17
GG
00
00
07
07
10
10
17
17
GG
00
00
07
07
10
10
17
17
12448-I
5. Use your module’s installation data to make other wiring
connections.
Publication
1771–5.60 – May 1999
Universal I/O Chassis12
W
T
W
Specifications
I/O Chassis
I/O Chassis
Series B (Cat. No.)
1771-A2BSS panel
1771-A3B1SS panel
All Chassis
ype of Mount
Operating Temperature Storage Temperature
32
0o to 60oC
o
to 140oF
General Dimensions
General Dimensions
(W x H x D)
356 x 315 x 193mm
(14.0 x 12.4 x 7.6 inches)
483 x 315 x 193mm
(19.0 x 12.4 x 7.6 inches)
–40o to 85oC
o
(–40
to 185oF)
eight
eight
(without modules)
4.5kg (10lbs)
5.9kg (13lbs)
Relative Humidit
5 to 95% (without condensation)
I/O Module
I/O Module
Slots
8 16A
12 24A
y
Maximum
Maximum
Backplane Current
Allen-Bradley, a Rockwell Automation Business, has been helping its customers improve
productivity and quality for more than 90 years. We design, manufacture and support a broad
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