Allen-Bradley 1771-IB Installation and user guide

DC (12-24V) Input Module
Cat. No. 1771-IB
Installation Data
This document provides information on:
important pre–installation considerations
power supply requirements
initial handling procedures
installing the module
using the indicators for troubleshooting
module specifications
The 1771–IB module is compatible with the following 2 and 3–wire
devices:
DC proximity switches
photoelectric sensors
pushbuttons
limit switches
float switches
selector switches
The off–state leakage current of your 3–wire devices should not exceed
3mA.
This module contains input filtering to limit the effect of voltage transients
caused by contact bounce and/or radiated electrical noise. The delay due to
input filtering is nominally 12+7ms for turning inputs on, and 20+7ms for
turning inputs off.
Your module receives its power through the 1771 I/O chassis backplane
from the chassis power supply. The module requires 74mA from the output
of this supply. Add this to the requirements of all other modules in the I/O
chassis to prevent overloading the chassis backplane and/or backplane
power supply.
To The Installer
Pre-installation Considerations
Power Requirements

DC (12-24V) Input Module
Cat. No. 1771-IB
Installation Data
2
The dc input module is shipped in a static–shielded bag to guard against
electrostatic discharge damage. Observe the following precautions when
handling the module.
Electrostatic Discharge Damage
ATTENTION: Under some conditions, electrostatic discharge
can degrade performance or damage the module. Observe the
following precautions to guard against electrostatic damage.
Wear an approved wrist strap grounding device, or touch a grounded
object to discharge yourself before handling the module.
Do not touch the backplane connector or connector pins.
If you configure or replace internal components, do not touch other
circuit components inside the module. If available, use a static–free
work station.
When not in use, keep the module in a static–shielded bag.
In this section we tell you how to key your I/O chassis, install your module
and make your wiring connections.
Keying Your I/O Chassis
Use the plastic keying bands, shipped with each I/O chassis, to key the I/O
slots to accept only this type of module.
The module circuit board is slotted in two places on the rear edge. The
position of the keying bands on the backplane connector must correspond
to these slots to allow insertion of the module. You can key any connector
in an I/O chassis to receive this module except for the left–most connector
reserved for adapter or processor modules. Place keying bands between the
following numbers labeled on the backplane connector:
Between 4 and 6
Between 14 and 16
You can change the position of these keys if system redesign and rewiring
makes insertion of a different module necessary.
Initial Handling
Installing Your Module

DC (12-24V) Input Module
Cat. No. 1771-IB
Installation Data
3
Installing the Input Module
To install the dc input module in your 1771 Series B I/O chassis, follow the
steps listed below.
ATTENTION: Remove power from the 1771 I/O chassis
backplane and wiring arm before removing or installing an I/O
module.
Failure to remove power from the backplane or wiring arm
could cause module damage, degradation of performance, or
injury.
Failure to remove power from the backplane could cause
injury or equipment damage due to possible unexpected
operation.
1. Turn off power to the I/O chassis.
2. Place the module in the plastic tracks on the top and bottom of the
slot that guide the module into position.
3. Do not force the module into its backplane connector. Apply firm,
even pressure on the module to seat it properly.
4. Snap the chassis latch over the top of the module to secure its
position.
5. Connect the wiring arm to the module.
6. Make wiring connections to the field wiring arm as indicated in
Figures 1 and 2.
Connecting Wiring to the Input Module
Connections to the input module are made to the 10 terminal field wiring
arm (cat. no. 1771–WA) shipped with the module. Attach the wiring arm to
the pivot bar on the bottom of the I/O chassis. The wiring arm pivots
upward and connects with the module so you can install or remove the
module without disconnecting the wires.
ATTENTION: Observe proper polarity with dc power
connections. Reverse polarity, or application of ac voltage could
damage the module.

DC (12-24V) Input Module
Cat. No. 1771-IB
Installation Data
4
Figure 1
Connection
Diagram (2-W ire Devices)
Input 0
Input 1
Input 2
Input 3
Input 4
Input 5
Input 6
Input 7
DC Common
Not used
DC
Power Supply
+
-
(See Applicable Codes and Laws)
A
0
1
2
3
4
5
6
7
B
(Actual wiring runs in this direction.)
11833-I
Connect one terminal of your 2 or 3–wire input device to terminals 0
through 7 (Figure 1). Connect 3–wire input devices, such as Allen–Bradley
proximity switches (Bulletin 871) to operate in a current source mode
(Figure 2).
Connect terminal B to the dc common. Terminal A is not used. Connect the
+dc line to the other terminal of your input devices. Use stranded 14 or 16
gauge wire to minimize the voltage drop over long cable distances.
Important: You can directly drive terminals on an DC (12–24V) Input
Module (cat. no. 1771–IB) from terminals on the following modules:
DC (10–60V) Output module (cat. no. 1771–OBD)
DC (12–24V) Output module (cat. no. 1771–OB)
Important: Use the same dc power source to power both modules to
ensure that ground is at the same potential.

DC (12-24V) Input Module
Cat. No. 1771-IB
Installation Data
5
Figure 2
Connection
Diagram (3-W ire Devices)
DC
Power Supply
+
+
+
-
Input 0
Input 1
Input 2
Input 3
Input 4
Input 5
Input 6
Input 7
DC Common
Not used
See Applicable Codes and Laws
A
0
1
2
3
4
5
6
7
B
(Actual wiring runs in this direction.) 11834-I
The front panel of your module contains 8 red status LED indicators
(figure 3). The red status indicators are provided for system logic side
indication of individual inputs. When a red LED lights, voltage is present
on the terminal. The module transfers this information to the backplane for
the processor to read.
Figure 3
Status
Indicators
Not used
Input 0
Input 1
Input 2
Input 3
Input 4
Input 5
Input 6
Input 7
Status Indicators
11835-I
Interpreting the Status
Indicators

Specifications
DC (12-24V) Input Module
Cat. No. 1771-IB
Installation Data
6
Inputs per Module 8
Module Location 1771 I/O chassis
Input Voltage Range 10 to 27V dc
Nominal Input Current 8mA at 12V dc
24mA at 24V dc
Maximum Off-state Current 3.0mA
Maximum Off-state Voltage 7.0V dc
Minimum On-state Voltage 10V dc
Input Impedance 1 to 2K ohms maximum (on-state)
2 to 3K ohms maximum (off-state)
Input Signal Delay Low to high propagation delay 12ms +7ms
High to low propagation delay 20ms +7ms
Power Dissipation 5.7 Watts (max.), 0.4 Watts (min.)
Thermal Dissipation 19.3 BTU/hr (max.), 1.4 BTU/hr (min.)
Backplane Current 74mA @ 5V dc +5%
Opto-electrical Isolation 1500V ac rms
Environmental Conditions
Operational Temperature
Storage Temperature
Relative Humidity
0oto 60oC (32oto 140oF)
-40oto 85oC (-40oto 185oF)
5 to 95% (without condensation)
Conductors Wire Size
Category
14 gage stranded maximum
3/64 inch insulation maximum
21
Keying Between 4 and 6
Between 14 and 16
Field Wiring Arm Catalog Number 1771-WA
1Refer to publication 1770-4.1, Programmable Controller Wiring and Grounding Guidelines.
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companies — Allen-Bradley meets today’s challenges of industrial automation with over
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Publication 1771–2.4 – May 1990
Supersedes publication 1771–2.4 – January 1986 and 1771–2.4–DU1 – October 1987 PN 955107–15 Copyright 1991 Allen-Bradley Company, Inc. Printed in USA