User Manual · Publication 1766-UM001 · Rockwell Automation
MicroLogix 1400 Programmable Controllers — User Manual
Hardware overview, installation, wiring, and specifications for the Allen-Bradley MicroLogix 1400 family (Bulletin 1766) and the 1762 expansion I/O it supports. All six 1766-L32 catalog numbers carry 32 discrete I/O plus three comm ports (isolated RS-232/RS-485 combo, 10/100 Ethernet, and non-isolated RS-232); "AA" / "BA" variants add 4 analog inputs and 2 analog outputs.
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Specifications
Performance & Memory
| Number of I/O | 32 discrete (20 in / 12 out); AA/BA variants add 4 analog in + 2 analog out |
|---|---|
| Memory module | 1766-MM1, 384 KB (optional backup; non-volatile program already stored in controller) |
| Real-time clock | Built-in (all models); field-replaceable lithium battery backup |
| Programming software | RSLogix 500 / RSLogix Micro v8.10.00+ (Series A) or v8.30.00+ (Series B/C) |
| Max expansion I/O modules | 7 (any combination, see System Loading for heat budget) |
| High-speed counter | Up to 40 kHz (6 HSC inputs) |
| PTO / PWM outputs | Up to 40 kHz on FET-output models (1766-L32BXB / L32BXBA) |
| Auto Reset functionality | FRN 21.007+ can auto-restart from 2H/4H/8H/9H faults when S:36/1 is set |
Electrical — Controller
| Input power — AC models (AWA/BWA/AWAA/BWAA) | 100…240V AC (-15%, +10%) @ 47…63 Hz |
|---|---|
| Input power — DC models (BXB/BXBA) | 24V DC (-15%, +10%), Class 2 SELV |
| Power consumption | AWA/BWA: 100 VA (130 VA Series C); BXB: 50 W (7.5 W with no 1762 expansion I/O) |
| AC inrush current | 120V AC: 25 A for 8 ms; 240V AC: 40 A for 4 ms |
| DC inrush current (BXB) | 15 A for 20 ms |
| 24V DC sensor power (BWA/BWAA) | 250 mA @ 24V DC, 400 µF max capacitive load (500 mV pk-pk ripple) |
| Input circuit types | Digital: 120V AC (AWA) or 24V DC sink/source (BWA/BXB); Analog: 0…10V DC |
| Output circuit types | Relay (AWA/BWA/AWAA/BWAA); Relay + FET (BXB/BXBA) |
| Relay life | Mechanical 20,000,000 cycles; electrical see Relay Life Chart |
| Relay contact (240V AC / 120V AC / 24V DC) | 2.5 A continuous, 1800 VA make, 180 VA break |
| Analog input range / resolution | 0…10V DC, 12-bit unsigned integer (0…4095), ±0.5% full scale non-linearity |
| Analog output range | 0…10V DC, 12-bit unsigned integer, >1 kΩ load, 3 ms settling |
| Fast DC input filter (Inputs 0…11 on BWA/BXB) | 5 nominal settings from 0.005 ms (100 kHz HSC) to 16 ms (31 Hz) |
Environmental
| Operating temperature | 0…+55 °C (+32…+131 °F) ambient |
|---|---|
| Storage temperature | -40…+85 °C (-40…+185 °F) |
| Operating humidity | 5…95% relative, non-condensing |
| Vibration (operating) | 10…500 Hz, 5 g, 0.030 in. max peak-to-peak (relay operation: 1.5 g) |
| Shock (operating) | 30 g, 3 pulses each direction, each axis (relay operation: 7 g) |
| Shock (non-operating) | 50 g panel-mounted / 40 g DIN-rail |
| ESD immunity | IEC 61000-4-2: 4 kV contact / 8 kV air, 4 kV indirect |
| Radiated RF immunity | 10 V/m, 80…1000 MHz, 80% AM + 900 MHz keyed carrier (IEC 61000-4-3) |
| EFT/B immunity | ±2 kV @ 5 kHz on power ports; 1 kV on communication cables (IEC 61000-4-4) |
| Enclosure type rating | None (open-style, DIN rail or panel mount) |
Physical
| Dimensions (H × W × D) | 90 × 180 × 87 mm (3.5 × 7.08 × 3.43 in.) |
|---|---|
| Shipping weight | 900 g (31.74 oz) |
| Mounting | 35 mm DIN rail or panel mount |
| Terminal screw torque | 0.791 N·m (7.0 lb·in) |
Catalog Number Format
How to read an Allen-Bradley 1766 catalog number. Each position encodes a specific configuration attribute.
Position
Meaning
Example
1766
Bulletin prefix for MicroLogix 1400
1766-L32BWA → Bulletin 1766
-L32
Controller class with 32 on-board discrete I/O
-L32 (all 1766 controllers)
A / B
Input type — A = 120V AC inputs, B = 24V DC inputs
L32AWA = AC inputs; L32BWA = DC inputs
W / X
Output type — W = relay only, X = relay + FET transistor
L32BWA = relay outputs; L32BXB = relay + FET (supports PTO/PWM up to 40 kHz)
A / B
Input power — A = 100/240V AC supply, B = 24V DC supply
L32BWA = 120/240V AC powered; L32BXB = 24V DC powered
A suffix (AA / BA)
Embedded analog — adds 4 voltage inputs and 2 voltage outputs; omit for discrete-only
L32BWAA = discrete + 4 AI / 2 AO; L32BWA = discrete only
Communication Protocols
Supported industrial networks and field buses for the products covered by this publication.
EtherNet/IP (Channel 1) 10/100 Mbps; CIP explicit messaging only (no implicit/real-time I/O). Embedded web server.
Modbus TCP Slave over Channel 1 (Ethernet); enable via protocol config
DNP3 over IP Master or slave over Channel 1; replaces Modbus TCP when enabled
DF1 Full-Duplex / Half-Duplex (Channels 0 and 2) Point-to-point, radio modem, or half-duplex master/slave over RS-232
DH-485 (Channel 0) Direct RS-485 connect via Channel 0 combo port or 1761-NET-AIC converter
Modbus RTU master/slave Channels 0 and 2; selectable Stop/Data Bits per firmware FRN4+
ASCII (Channels 0 and 2) For barcode readers, weigh scales, printers, and serial devices
DNP3 slave (RS-232) Channel 0 or Channel 2
Ethernet-via-legacy-bridge 1761-NET-ENI / 1761-NET-ENIW for sites using DF1 gateways
Certifications & Compliance
c-UL-us Listed Industrial Control Equipment (UL File E322657)
c-UL-us Listed Class I Division 2 Groups A,B,C,D Hazardous Locations (UL File E334470)
CE — EN 61326-1 (EMC), EN 61000-6-2 (Industrial Immunity), EN 61000-6-4 (Emissions), EN 61131-2 (Programmable Controllers Clause 8, Zone A & B)
CE LVD — EN 61131-2 Clause 11
CE RoHS — EN IEC 63000
UKCA — 2016 No. 1091 EMC, 2016 No. 1101 Electrical Safety, 2012 No. 3032 RoHS
RCM (Australia / New Zealand) — EN 61000-6-4
KC (South Korea) — Radio Waves Act Article 58-2 Clause 3
Document Contents
Full PDF covers the following topics in detail:
- Catalog number breakdown for all six 1766-L32 MicroLogix 1400 variants
- Hardware features, LCD keypad operation, and status indicator details
- Installation — DIN rail, panel mount, spacing, and expansion-bus connection
- Wiring — sinking/sourcing diagrams, surge suppression, analog channel grounding
- Communication setup — RS-232/RS-485 combo port, Ethernet, DH-485, Modbus, DNP3
- LCD and keypad — I/O status, file monitoring, mode switch, Ethernet config, trim pots
- Controller specifications: power, memory module, RTC, I/O, analog resolution
- 1762 Expansion I/O specifications — input, output, and analog module ratings
- Working voltage and dielectric isolation tables per catalog number
- Certifications: c-UL-us, CE, UKCA, RCM, KC, Class I Div 2
- Firmware revision history (FRN1 through FRN21+) and feature-by-feature changelog
- Auto Reset functionality (FRN 21.007+) for automatic fault recovery
Frequently Asked Questions
Which MicroLogix 1400 catalog number fits my application?
Start with input power and I/O type: 1766-L32AWA (AC input / AC inputs / relay out), 1766-L32BWA (AC input / DC inputs / relay out), 1766-L32BXB (DC input / DC inputs / relay + FET). Add the "A" suffix — L32AWAA, L32BWAA, L32BXBA — if you need 4 embedded analog inputs and 2 analog outputs. Use a BXB/BXBA if you need PTO or PWM up to 40 kHz; the AC-input L32AWA is a good fit for legacy 120V AC field devices.
What makes the 1400 different from the MicroLogix 1200 or 1100?
The 1400 adds a third comm port (non-isolated RS-232), a 10/100 Ethernet port with CIP explicit messaging, DNP3 master/slave support, and Modbus TCP. It keeps the MicroLogix 1200's 1762 expansion-I/O backplane (up to 7 modules) but steps up to an LCD keypad, embedded web server, and a 384 KB memory module option (1766-MM1). I/O count is fixed at 32 on-board discrete points.
Is the MicroLogix 1400 a Modbus RTU master, and can it also run ASCII simultaneously?
Channels 0 and 2 can each be configured independently as Modbus RTU master, Modbus RTU slave, DF1 full- or half-duplex, DH-485, ASCII, or DNP3 slave. You cannot run Modbus and ASCII on the *same* channel at the same time, but you can run Modbus RTU on Channel 0 and ASCII (for a barcode reader, say) on Channel 2 concurrently. Modbus TCP runs on Channel 1 (Ethernet) and does not conflict.
How many expansion I/O modules can a 1400 support?
A maximum of seven 1762 expansion I/O modules, in any combination. The practical limit is often heat: the appendix "System Loading and Heat Dissipation" worksheet sums per-module dissipation against the enclosure rating. Typical analog modules (1762-IF4, IR4, IT4) draw 40 mA at 5V DC plus 50…165 mA at 24V DC; discrete DC input/output modules draw 50…175 mA at 5V DC.
Which communication cable do I need?
For programming/point-to-point on Channel 0 (8-pin mini-DIN RS-232/RS-485 combo), use 1761-CBL-AM00, AP00, PM02, or HM02 (Series C or later). For RS-485 network use 1763-NC01, and for a standard RS-232 PC with DB9 use 1747-CP3. Channel 2 is a 9-pin D-shell RS-232C and accepts any standard RS-232 cable. Channel 1 is RJ45 Ethernet.
Does the 1400 support CIP implicit messaging (real-time I/O over EtherNet/IP)?
No. The embedded Ethernet port supports CIP *explicit* messaging only (message exchange, MSG instruction, RSLinx OPC topic, web server access). It cannot act as a CIP scanner or target for real-time I/O data. For real-time I/O over EtherNet/IP use a CompactLogix 5370 / 5380 or ControlLogix.
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