How-To Guide

Allen-Bradley 1734-IB8 POINT I/O Digital Input Module

Complete setup guide for the 8-channel 24VDC sinking digital input module: system assembly, field wiring, Studio 5000 configuration, programming examples, and diagnostics for the POINT I/O platform.

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8 Input Channels
24VDC Rated Voltage
Sink Input Type
1734 POINT I/O Platform

How-To Guide  ·  Allen-Bradley POINT I/O  ·  Digital Input Configuration

1734-IB8: Installation, Wiring, Configuration, and Programming Guide

Part Number: 1734-IB8  ·  POINT I/O Platform · 8-Channel 24VDC Sink Input · Studio 5000 Logix Designer

The 1734-IB8 is an 8-channel 24VDC sinking digital input module for the Allen-Bradley POINT I/O platform. It connects to a controller via a POINT I/O communication adapter (1734-AENT for EtherNet/IP, 1734-ACNR for ControlNet, or 1734-ADN for DeviceNet) across the POINTBus backplane. The POINT I/O system uses a modular 3-piece design: terminal base, I/O module, and removable terminal block (RTB). This guide covers system assembly, field wiring, Studio 5000 configuration, ladder logic examples, and LED diagnostics.

1. Module Overview

The 1734-IB8 is a fixed 8-point sinking digital input module for the POINT I/O platform. It reads 24VDC discrete signals and maps them into a single byte of input data (1 bit per channel). The module supports selectable input filter times from 0 to 65 ms, 1 ms default (1734-UM001) with a 1 ms default for noise rejection.

Catalog Number Breakdown

CodeMeaningValue
1734PlatformPOINT I/O -- modular distributed I/O
IModule typeInput
BSignal typeDC sinking (B = DC sink; V = DC source)
8Channel count8 discrete input points

Key Specifications

ParameterValue
Number of Inputs8 (1 group of 8), sinking
DiagnosticsNo (standard IB8 has no per-channel diagnostics)
Voltage, On-State (nominal)24V DC
Voltage, On-State (range)10 -- 28.8V DC
Voltage, Off-State (max)5V DC
Current, On-State (nominal)4 mA @ 24V DC
Current, On-State (range)2 mA -- 5 mA
Current, Off-State (min)1.5 mA
Impedance, Input (nominal)3.6 kΩ
Impedance, Input (max)4.7 kΩ
Input Filter Time0.5 ms hardware + (0 -- 65 ms user-selectable, 1 ms default) -- Off-to-On and On-to-Off (1734-UM001)
POINTBus Current (max)75 mA @ 5V DC
Power Dissipation (max)1.6 W @ 28.8V DC
Thermal Dissipation (max)5.5 BTU/hr @ 28.8V DC
Isolation Voltage50V continuous, reinforced insulation. Type tested at 2500V DC for 60 s, field-side to system.
External DC Power Supply (nominal)24V DC
External DC Power Supply (range)10 -- 28.8V DC
Dimensions (H x W x D)56.6 x 12.1 x 77.5 mm (2.23 x 0.48 x 3.05 in.)
Weight32.3 g (1.14 oz)
Terminal Base1734-TB, 1734-TBS, 1734-TOP, or 1734-TOPS
Wiring Category1 -- on signal ports
Keyswitch Position1
Operating Temperature-20 to +55°C (-4 to +131°F)
Enclosure TypeNone (open-style)
Hazardous LocationClass I Division 2, ATEX Zone 2, IECEx
POINT I/O vs. Compact 5000 Unlike the Compact 5000 (5069) platform which connects directly to a CompactLogix controller via a local I/O bus, POINT I/O modules communicate through a separate network adapter (1734-AENT for EtherNet/IP, 1734-ACNR for ControlNet). This makes POINT I/O ideal for distributed I/O applications where modules are located away from the controller -- in remote panels, junction boxes, or machine-mounted enclosures.

2. Hardware Installation

The POINT I/O system uses a No Tools design. The terminal base mounts to a DIN rail, the I/O module snaps into the base, and the removable terminal block (RTB) clips onto the front for field wiring.

System Assembly Order

PositionModuleExample
Slot 0 (leftmost)Communication Adapter1734-AENT (EtherNet/IP), 1734-ACNR (ControlNet), or 1734-ADN (DeviceNet)
Slot 1 -- 13I/O Modules1734-IB8 in any available slot (up to 13 modules on a 1734-AENT, POINTBus current permitting; up to 63 with 1734-EP24DC/EPAC expansion power supplies; 10 A max field power)
OptionalExpansion Power Supply1734-EPAC or 1734-EP24DC (if field power bus needs extending)

Installation Steps

  1. Mount the terminal base on the DIN rail. Position the 1734-TB or 1734-TBS terminal base vertically above the rail. Hook the top rail clip, then press the bottom until the locking mechanism engages. The base interlocking side pieces connect to the adjacent base to form the POINTBus backplane.
  2. Set the keyswitch to position 1. Use a bladed screwdriver to rotate the keyswitch on the mounting base clockwise until the number 1 aligns with the notch. Verify the DIN rail locking screw is in the horizontal position.
  3. Slide the I/O module into the terminal base. Insert the module straight down into the mounting base and press to secure. The module locks into place and engages the POINTBus connector on the base automatically.
  4. Snap the RTB onto the module. Hook the RTB end into the base unit curved section, rotate the terminal block into the wiring base until it locks, then snap the RTB handle into place on the module. The RTB can be pre-wired at a bench before installation.
  5. Note the slot position. Modules are numbered left to right. The adapter occupies slot 0; the first I/O module to its right is slot 1. Record the slot number for Studio 5000 configuration.
  6. Set the adapter chassis size. Set the chassis size to 1 (the adapter) plus the number of I/O modules. The adapter makes no I/O connections until the chassis size matches the modules present (1734-UM011, Set the Chassis Size).
  7. Apply power. Connect 24V DC field power to the communication adapter's field power terminals. The POINTBus distributes backplane power to all modules.
Removal and Insertion Under Power (RIUP) POINT I/O supports Removal and Insertion Under Power (RIUP). Removing one module does not disrupt the other modules; the adapter flashes its POINTBus Status LED red and reports a minor recoverable fault. If you remove more than one adjacent module, none of them reconnect until all are replaced (1734-UM011). When you insert or remove the module or the RTB with power on, an electric arc can occur; in a Class I Division 2 location, remove power or verify the area is nonhazardous first (1734-IN051).

Terminal Block Options

The 1734-IB8 mounts on one of these wiring base assemblies (1734-IN051, Module location):

Terminal BaseTypeDescription
1734-TB / 1734-TBSTwo-piece (mounting base + RTB)Screw-clamp (TB) or spring-clamp (TBS). The RTB unplugs from the mounting base, so the base can be replaced without rewiring.
1734-TOP / 1734-TOPSOne-pieceScrew-clamp (TOP) or spring-clamp (TOPS). Terminal base and wiring in one unit.

Terminal Block Removal

  1. Pull up on the RTB handle on the I/O module to unlatch it.
  2. Pull on the RTB handle to remove the RTB from the wiring base.
  3. To reinstall, hook the RTB end into the base unit, rotate until it locks, and snap the RTB handle into place.

For 1734-RTBS and 1734-RTB3S spring-clamp terminals, insert a bladed screwdriver (1492-N90, 3 mm diameter) into the opening at approximately 73° to latch and unlatch the wire. For 1734-TOPS and 1734-TOP3S, insert at approximately 97° and press in.

3. Wiring

Terminal Assignments

The 1734-IB8 has 8 terminal positions. On the 1734-TB and 1734-TBS bases, the terminals are arranged in a column. Field power (V = supply, C = common) is daisy-chained from the communication adapter, 1734-FPD field power distributor, 1734-EP24DC expansion power supply, or from a user-supplied external auxiliary terminal block.

PinFunctionDescription
0Input 0Channel 0 -- field device signal
1Input 1Channel 1 -- field device signal
2Input 2Channel 2 -- field device signal
3Input 3Channel 3 -- field device signal
4Input 4Channel 4 -- field device signal
5Input 5Channel 5 -- field device signal
6Input 6Channel 6 -- field device signal
7Input 7Channel 7 -- field device signal

All 8 RTB terminals are inputs, so the 1734-IB8 has no V or C terminal for sensor power. Take sensor +V and common from a user-supplied auxiliary terminal block (or the V/C terminals of the adapter, 1734-FPD or 1734-EP24DC), daisy-chained as shown in 1734-IN051. Use the 1734-TB, TBS, TOP or TOPS base.

Wire Specifications

ParameterValue
Wire Size0.25 -- 2.5 mm² (24 -- 14 AWG) for 1734-RTB; 0.08 -- 2.5 mm² (28 -- 14 AWG) for 1734-RTBS; 1 wire per cavity
Wire Size (18 AWG)0.75 mm², 2 wires per cavity (stranded only)
Strip Length (without ferrule)16 ± 1 mm (0.63 ± 0.03 in.); 18 ± 1 mm for two 18 AWG wires
Signal Terminal Voltage28.8V DC, 120/240V AC max
Signal Terminal Current2 A max
Terminal Base Screw Torque0.8 N·m (7 lb·in)

Sink Wiring Configuration

For sink wiring (the standard configuration for the 1734-IB8), connect field devices as follows:

FromToDescription
+24VDC field supplyField device (one side)Positive leg of field power supply
Field device (other side)Module input terminal (pin 0 -- 7)Signal wire to the input channel
DC COM (0V)Auxiliary terminal block common (daisy-chained from the adapter, 1734-FPD or 1734-EP24DC C terminal)Return for 3-wire sensors (BU) and the field supply

Typical Field Device Wiring Examples

Field DeviceContact TypeWiringNotes
Pushbutton (Start)Normally Open (NO)+24V → PB → Input pinInput ON when pressed
Pushbutton (Stop / E-Stop)Normally Closed (NC)+24V → PB → Input pinInput ON normally; OFF when pressed. For an E-stop this is a status signal only; the stop itself must be hardwired or safety-rated
3-Wire PNP Proximity SensorPNP sourcing+24V → BN; BK → Input pin; BU → 0VPNP sensors recommended with sink inputs -- ON/OFF matches active/inactive
2-Wire Proximity Sensor2-wire+24V → sensor → Input pinSensor wires in series between supply and input; verify leakage current is below off-state threshold (1.5 mA)
Limit SwitchNO or NC+24V → Switch → Input pinNC wiring makes a broken wire read as OFF
Overload Relay (95-96)NC+24V → 95 → 96 → Input pinInput ON = normal; OFF = tripped (fail-safe)
Field Power Distribution The 1734-IB8 receives its field-side power through the POINTBus backplane, originating from the communication adapter's 24V DC field power terminals (10 -- 28.8V DC, 10 A max). Only signal wires land on the 8-pin RTB. Sensor +V and 0V for 3-wire devices come from an auxiliary terminal block daisy-chained from the adapter, 1734-FPD or 1734-EP24DC (1734-IN051).
Field Power Budget Each communication adapter supports a maximum of 10 A field power current across all modules on the bus. When planning your I/O configuration, total the field-side current draw of all modules. If the budget is exceeded, add an expansion power supply (1734-EPAC or 1734-EP24DC) to create a new field power segment.

4. Studio 5000 Configuration

POINT I/O modules are configured through the communication adapter in Studio 5000. The adapter appears in the I/O tree, and individual I/O modules are added as children of the adapter. This Series D product can be used with DeviceNet and PROFIBUS adapters, and with ControlNet and EtherNet/IP adapters using RSLogix 5000 software version 11 or later or Studio 5000 Logix Designer application version 20 or later.

Adding the Module to the I/O Tree

  1. In Studio 5000 Logix Designer, expand Controller Organizer → I/O Configuration → expand your EtherNet/IP network or ControlNet network → expand the 1734-AENT or 1734-ACNR adapter node.
  2. Right-click the adapter → New Module.
  3. In the module search dialog, type 1734-IB8 and select it. Click Create.
  4. Set the Name -- use a descriptive name such as DI_Remote1.
  5. Set the Slot number to match the physical position (the adapter is slot 0; Slot 1 = first module to the right of the adapter).
  6. Click OK. The module appears under the adapter in the I/O tree.

Connection Settings

SettingOptionsRecommendation
RPI (Requested Packet Interval)Direct Connection = 50 ms; Rack Optimization = not selectableDefault 50 ms for direct connection. For digital inputs where response time matters, keep at 50 ms or adjust based on application needs.
Connection TypeData (default), Listen Only, Listen Only - Rack Optimization, Rack OptimizationData (default) for most applications. Rack Optimization reduces network traffic by combining multiple modules into one connection.
Data FormatIntegerInteger is the only option for digital modules.

Input Filter Configuration

The 1734-IB8 supports separate Off-to-On and On-to-Off input filter times for each channel. Open the Configuration tab in module properties to set filter values. Enter each filter value in milliseconds; the default is 1 ms (1734-UM001).

FeatureDescription
ChannelChannels 0 through 7 -- each individually configurable
Input Filter Time (ms)Off-to-On and On-to-Off transition filter constant. A high signal must be present for this duration before the module reports On. A low signal must be present for this duration before reporting Off. Default is 1 ms. The hardware imposes a fixed 0.5 ms minimum filter.

Filter Time Recommendations

Filter TimeUse Case
0 ms (Off)High-speed signals, externally debounced sensors
1 ms (Default)Clean electronic signals -- proximity sensors, photoelectric sensors
5 -- 10 msGeneral purpose -- good balance of speed and noise rejection
10 -- 20 msMechanical contacts -- limit switches, relay contacts
20 -- 65 msPushbuttons, toggle switches, very noisy environments
Create Aliases for Readability Always create alias tags for your I/O points. Right-click any I/O tag → New Tag → set the Type to Alias and point it to the I/O address. For example, alias PB_Start to the input address. This makes your ladder logic self-documenting and simplifies maintenance.

5. Reading Inputs in Ladder Logic

Digital inputs from the 1734-IB8 are read using standard ladder logic instructions. The module produces 1 byte of input data -- 8 bits, one per channel.

Instructions

InstructionNameFunction
XICExamine If ClosedTRUE when the bit is 1 (input is ON). Equivalent to a normally open contact.
XIOExamine If OpenTRUE when the bit is 0 (input is OFF). Equivalent to a normally closed contact.

Data Map

The 1734-IB8 produces 1 byte of scanner Rx data. It does not consume any scanner Tx data.

DirectionBit 7Bit 6Bit 5Bit 4Bit 3Bit 2Bit 1Bit 0
Produce (scanner Rx)Ch7Ch6Ch5Ch4Ch3Ch2Ch1Ch0
Consume (scanner Tx)No consumed data

Where: Ch0 = Input channel 0, Ch1 = Input channel 1, ... Ch7 = Input channel 7. 0 = Off, 1 = On.

Practical Example: Motor Start/Stop with Status Monitoring

This example shows a motor control circuit using the 1734-IB8 in Slot 1 for inputs and a 1734-OB8 (8-point digital output) in Slot 2 for outputs.

Not a safety circuit. The 1734-IB8 and the controller logic below are standard control, not a safety function. The E-stop must remove power from the contactor through a hardwired circuit or a rated safety relay / POINT Guard I/O (1734-IB8S/OB8S) system (1734-SG001). The EStop_OK input here only reports the E-stop state to the program.

I/O Assignment Table

Tag AliasI/O AddressModuleField DeviceContact Type
PB_StartAdapter:1:I.Data.01734-IB8 Slot 1Green pushbuttonNO momentary
PB_StopAdapter:1:I.Data.11734-IB8 Slot 1Red pushbuttonNC momentary (wired NC)
EStop_OKAdapter:1:I.Data.21734-IB8 Slot 1E-Stop auxiliary (status) contactNC (status only)
OL_OKAdapter:1:I.Data.31734-IB8 Slot 1Overload relay (95-96)NC (opens on trip)
Motor_RunAdapter:2:O.Data.01734-OB8 Slot 2Motor contactor coil24VDC coil
Pilot_RunAdapter:2:O.Data.11734-OB8 Slot 2Green pilot light24VDC LED
Pilot_FaultAdapter:2:O.Data.21734-OB8 Slot 2Red pilot light24VDC LED
PB_FaultResetAdapter:1:I.Data.41734-IB8 Slot 1Blue pushbuttonNO momentary
Motor_FaultInternal tag(controller)BOOL, latched overload fault--

Ladder Logic (Structured Text Representation)

// ── Motor_1 Control Routine ───────────────────────────────── // Module: 1734-IB8 in Slot 1 (inputs), 1734-OB8 in Slot 2 (outputs) // Adapter: 1734-AENT EtherNet/IP adapter // // Tag Aliases: // PB_Start → Adapter:1:I.Data.0 (NO momentary pushbutton) // PB_Stop → Adapter:1:I.Data.1 (NC momentary -- wired NC, ON = normal) // EStop_OK → Adapter:1:I.Data.2 (NC E-Stop status contact, ON = normal; status only) // OL_OK → Adapter:1:I.Data.3 (NC overload relay, ON = normal) // PB_FaultReset → Adapter:1:I.Data.4 (NO momentary reset pushbutton) // Motor_Run → Adapter:2:O.Data.0 (Motor contactor coil) // Pilot_Run → Adapter:2:O.Data.1 (Green run indicator) // Pilot_Fault→ Adapter:2:O.Data.2 (Red fault indicator) // Motor_Fault (internal BOOL -- latched overload fault) // ───────────────────────────────────────────────────────────── // Rung 1 -- Fault latch (evaluated before the seal-in so a trip is captured) IF NOT OL_OK THEN Motor_Fault := 1; END_IF; // Rung 2 -- Start/Stop seal-in with permissives (standard logic, not a safety function) IF (PB_Start OR Motor_Run) AND PB_Stop AND EStop_OK AND OL_OK AND NOT Motor_Fault THEN Motor_Run := 1; ELSE Motor_Run := 0; END_IF; // Rung 3 -- Fault reset IF PB_FaultReset AND OL_OK AND EStop_OK THEN Motor_Fault := 0; END_IF; // Rung 4 -- Pilot lights Pilot_Run := Motor_Run; Pilot_Fault := Motor_Fault;
NC Wiring and XIC Logic The Stop pushbutton, E-Stop, and overload relay are all wired with normally closed contacts. In their normal (safe) state, the input reads ON (1). The ladder logic uses XIC for these -- TRUE when normal. If a wire breaks or the E-Stop is pressed, the input goes OFF, breaking the seal-in rung. NC wiring makes a broken wire read as a stop, but this does not make standard I/O a safety device.

6. Diagnostics & Troubleshooting

LED Indicators

The 1734-IB8 has Module Status, Network Status, and 4 I/O channel status LEDs. The 4 I/O LEDs each represent two channels: LED 0 = Ch 0 & 4, LED 1 = Ch 1 & 5, LED 2 = Ch 2 & 6, LED 3 = Ch 3 & 7.

Module Status LED

LEDColorStateMeaning
Module StatusOffNo PowerNo power is applied to the device. Apply power.
Module StatusSteady greenNormalThe device is operating normally.
Module StatusFlashing greenStandbyThe device needs commissioning due to missing, incomplete, or incorrect configuration.
Module StatusFlashing redRecoverable FaultA recoverable fault is present. 1. Cycle power. 2. If condition persists, replace the device.
Module StatusSteady redUnrecoverable FaultAn unrecoverable fault occurred that may require device replacement.
Module StatusFlashing red/greenSelf-TestThe device is in self-test mode. No action required.

Network Status LED

LEDColorStateMeaning
Network StatusOffOfflineThe device is not online, has not completed dup_MAC_id test, or is not powered.
Network StatusFlashing greenNo ConnectionsThe device is online but has no connections in the established state.
Network StatusSteady greenConnectedThe device is online and has connections in the established state.
Network StatusFlashing redTimed OutOne or more I/O connections are in a timed-out state. Check for I/O module failure.
Network StatusSteady redCommunication FailureCritical link failure. The device has detected an error preventing communication.
Network StatusFlashing red/greenCommunication FaultedThe device has detected a network access error and is in a communication faulted state.

I/O Channel Status LEDs

LEDColorStateMeaning
I/O Status (per pair)OffInput OffBoth paired channels are in the Off state.
I/O Status (per pair)YellowInput OnOne or both of the paired channels is in the On state.

The 4 I/O LEDs each represent two channels: LED 0 = Ch 0 & 4, LED 1 = Ch 1 & 5, LED 2 = Ch 2 & 6, LED 3 = Ch 3 & 7. A LED lights yellow if either of its paired channels is On.

Common Faults and Resolutions

SymptomLikely CauseResolution
Module Status flashing greenConfiguration missing or incompleteVerify the module is added to the I/O tree in Studio 5000 with the correct slot number. Download the project.
Network Status offDevice not on the networkCheck that the communication adapter is powered and online. Verify the terminal bases are properly seated and the POINTBus backplane is continuous.
Network Status flashing redI/O connection timed outCheck the module is properly seated in its terminal base. Verify the RPI and connection type in Studio 5000.
Input LED is yellow but tag reads 0Module inhibited or project not downloadedRight-click module in I/O tree → Properties → Connection tab → verify "Inhibit Module" is unchecked. Re-download the project.
Input LED is off but field device is activatedWiring faultCheck field wiring: verify 24VDC at the field device output, check for broken wires, measure voltage at the input terminal (should be >10V when ON).
All 8 inputs read 0No field powerVerify 24VDC is connected to the communication adapter's field power terminals and the POINTBus is distributing power.
Input chatters ON/OFF rapidlyElectrical noise or contact bounceIncrease the input filter time for that channel. For mechanical contacts, try 10 -- 20 ms. Check cable routing and shielding.
Electronic Keying Studio 5000 supports electronic keying for POINT I/O modules. By default, Compatible Module keying is used -- the physical module must match the configured catalog number but allows minor revision differences. If you replace a module with a different series or revision, check the keying settings in module properties.
Automatic Device Replacement POINT I/O supports Automatic Device Replacement (1734-SG001). The module configuration lives in the controller project and is sent when the controller opens its connection: a replacement of the same type accepts that connection and is configured once it passes the electronic keying check (1734-UM011). No project download is needed.

7. Related POINT I/O Digital Input Modules

The POINT I/O platform includes several digital input module variants:

Catalog NumberChannelsTypeKey DifferenceTypical Application
1734-IB2224VDC Sink2 inputs in compact formLow-density applications, small machine I/O
1734-IB4424VDC Sink4 inputsMid-density applications
1734-IB4K424VDC Sink (Conformal Coated)Same as IB4 with conformal coatingHarsh environments
1734-IB8824VDC SinkStandard 8-point -- this guideGeneral purpose distributed I/O
1734-IB8K824VDC Sink (Conformal Coated)Same as IB8 with conformal coatingHigh humidity, corrosive atmospheres
1734-IB4D424VDC Sink with DiagnosticsPer-channel open wire and short circuit detectionApplications requiring field-side diagnostics
1734-IV2224VDC SourceSourcing input variantSourcing sensor applications
1734-IV4424VDC Source4 sourcing inputsMid-density sourcing
1734-IV8824VDC Source8 sourcing inputsHigh-density sourcing

8. Related Guides

GuideDescription
CompactLogix 5069-L306ER Setup GuideFirst-time setup for the CompactLogix 5380 controller -- power wiring, Studio 5000 project creation, and network setup.
5069-IB16 Digital Input Module GuideInstallation, wiring, and programming for the 16-channel Compact 5000 digital input module -- the local I/O equivalent of the 1734-IB8.

Reference Documentation

The following Rockwell Automation publications were used as references for this guide. These are the official manufacturer documents for the hardware covered in this article.

PublicationDescriptionDownload
1734-UM001POINT I/O Digital and Analog Modules and POINTBlock I/O Modules User ManualPDF
1734-IN051POINT I/O Input Modules Installation InstructionsPDF
1734-SG001POINT I/O Modules Selection GuidePDF

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