1756-L61S Allen-Bradley GuardLogix Safety Controller
Product Introduction
The 1756‑L61S from Allen‑Bradley is a GuardLogix safety controller that belongs to the ControlLogix family of programmable automation controllers. This processor provides 2 MB of standard user memory and 1 MB of dedicated safety memory, along with 478 KB of I/O memory for efficient data handling. It is designed to monitor and control I/O across the ControlLogix backplane and over network links. The 1756‑L61S supports DeviceNet, ControlNet, and EtherNet/IP communication via interface modules installed in the local chassis. A standout feature is its conformal coating, which applies a thin polymer layer to protect the circuitry from moisture, dust, and corrosive agents. This extends the product's operational life in demanding environments. Please be aware that this model has been discontinued by Rockwell Automation and is offered here for replacement or legacy system support.
Technical Specifications
The Allen‑Bradley 1756‑L61S delivers a solid set of technical parameters suitable for mid‑sized safety applications.
User Memory: 2 MB for standard control logic and application programs.
Safety Memory: 1 MB dedicated exclusively to safety‑related logic.
I/O Memory: 478 KB for efficient I/O data buffering and management.
Maximum Digital I/O: Supports up to 128,000 discrete I/O points.
Maximum Analog I/O: Handles up to 4,000 analog I/O channels.
Supported Networks: DeviceNet, ControlNet, and EtherNet/IP (via communication interface modules).
Communication Ports: No built‑in Ethernet or USB; requires local communication modules.
Task Capacity: Supports standard ControlLogix task scheduling with safety task integration.
Scalability: Multiple controllers can be installed in the same chassis for distributed control.
Conformal Coating: Provides protection against humidity, contaminants, and corrosive atmospheres.
Electrical & Power Parameters
Understanding the power requirements of the 1756‑L61S ensures proper integration into your ControlLogix system.
Current Draw (5.1V DC): 1200 mA – moderate consumption for a safety controller.
Current Draw (24V DC): 14 mA – minimal load on the 24V supply.
Power Dissipation: 3.5 W – low heat output suitable for standard enclosures.
Thermal Dissipation: 11.9 BTU/hr – manageable within typical industrial cabinets.
Isolation Voltage: 30 V continuous – provides basic insulation between internal circuits.
Enclosure Type: Open‑style (none) – designed for installation inside a protected ControlLogix chassis.
Lifecycle Status: Discontinued/Obsolete – available for legacy system support only.
Mechanical & Environmental Parameters
The 1756‑L61S is built to withstand demanding factory floor conditions with added protection from its conformal coating.
Operating Temperature: 0 °C to 60 °C (32 °F to 140 °F) for consistent performance.
Storage Temperature: -40 °C to 85 °C (-40 °F to 185 °F) for safe warehousing.
Relative Humidity: 5% to 95% non‑condensing – suitable for humid environments.
Shock Resistance: 30 g peak acceleration for 11 ms – meets industrial durability standards.
Vibration Resistance: 2 g at 10‑500 Hz – ensures stable operation near heavy machinery.
Conformal Coating: Polymer‑based protective layer that resists moisture, dust, and corrosive chemicals.
Slot Width: Occupies one slot in any 1756 series ControlLogix chassis.
Installation Guidelines
Proper installation of the Allen‑Bradley 1756‑L61S ensures reliable operation in your control system.
Chassis Slot: Insert the controller into any available slot within a ControlLogix 1756 chassis. Multiple controllers can coexist in the same chassis.
Communication Modules: For network connectivity, install the appropriate interface module (e.g., 1756‑ENBT for EtherNet/IP, 1756‑CNB for ControlNet, or 1756‑DNB for DeviceNet) in the local chassis.
Backplane Integration: The controller automatically communicates with I/O modules and communication adapters via the ControlLogix backplane.
Grounding: Ensure the chassis is properly grounded to prevent electrical noise interference.
Environmental Protection: The conformal coating provides built‑in defense, but additional cabinet sealing is recommended in highly corrosive atmospheres.
Power Supply: Pair with compatible 1756 series power supplies; verify total backplane load does not exceed capacity.
Legacy Note: As an obsolete model, verify firmware compatibility with existing system components before installation.
Packaging List
Each 1756‑L61S unit includes the following items in the box:
1 x Allen‑Bradley 1756‑L61S GuardLogix controller module (with conformal coating)
1 x Bus lever assembly for chassis mounting
1 x Quick‑start installation guide (printed)
1 x Anti‑static protective packaging bag
Note: Communication modules, power supplies, mounting hardware, and cables are sold separately.
Shipping & Delivery
All orders for the 1756‑L61S are processed and shipped within 24 hours of order confirmation. We utilize FedEx, UPS, or DHL for global delivery based on your location and preference. Tracking numbers are provided via email once the shipment departs our warehouse. Estimated delivery time is 3‑7 business days for most regions, with expedited shipping available upon request.
Frequently Asked Questions (FAQ)
1. Is the 1756‑L61S still in production?
No, the 1756‑L61S has been discontinued by Rockwell Automation and is now obsolete. We offer this unit for replacement or legacy system maintenance purposes only.
2. What networks does the 1756‑L61S support?
The Allen‑Bradley 1756‑L61S supports DeviceNet, ControlNet, and EtherNet/IP. However, you must install the appropriate communication interface module in the local chassis for each network type.
3. Does the 1756‑L61S have built‑in Ethernet or USB ports?
No, the 1756‑L61S does not include onboard Ethernet or USB connectivity. All network communication requires separate 1756 series communication modules installed in the same chassis.
4. What is the purpose of the conformal coating on the 1756‑L61S?
The conformal coating is a thin polymer layer that protects the 1756‑L61S circuitry from moisture, dust, and corrosive chemicals. This extends the controller's service life in harsh industrial environments.
5. Can the 1756‑L61S be used as a standard controller without safety functions?
Yes, the 1756‑L61S can operate as a standard ControlLogix controller if you do not utilize the safety memory or safety task features. However, its primary design is for safety‑integrated applications.
