1756-L73SK | AB Allen-Bradley GuardLogix Controller Module

Product Summary

The Allen-Bradley 1756-L73SK is a GuardLogix 5570 Safety Controller by Rockwell Automation, featuring 8 MB standard memory + 4 MB safety memory with conformal coating. It combines standard and safety control in a single module with SIL 3 / PLe certification, and supports ControlLogix redundancy for fault-tolerant applications. The -K suffix denotes the conformal coated version for enhanced protection in harsh industrial environments.

Core Specifications

• Model Number: 1756-L73SK
• Type: GuardLogix 5570 Safety Controller with Conformal Coating
• Safety Rating: SIL 3 / PLe (Cat 4)
• Standard Memory: 8 MB
• Safety Memory: 4 MB
• Non-Volatile Memory: 1784-SD1 (1 GB SD card included)
• I/O Capacity: 128,000 digital / 4,000 analog I/O points
• Controller Connections: 500
• EtherNet/IP Nodes: 32
• Motion Axes: 8 CIP motion axes
• Chassis Slots: 4, 7, 10, 13, 17 (1756 series)
• Communication: USB 2.0 (programming); EtherNet/IP, ControlNet, DeviceNet via 1756 communication modules
• Display: 4-character alpha/numeric
• Programming: Studio 5000 Logix Designer
• Manufacturer: Allen-Bradley by Rockwell Automation

Electrical & Functional Characteristics

• Backplane Current: 1.1 A at 5.1 VDC; 3 mA at 24 VDC
• Power Dissipation: 6.2 W typical
• Task Types: Continuous, periodic, event, and safety tasks
• Safety Task Period: Configurable down to 6 ms
• Dual-Processor Architecture: Separates safety and standard logic execution
• Redundancy Support: Compatible with 1756-RM2 redundancy modules for paired chassis configurations
• Conformal Coating: Protects circuit boards from moisture, dust, and corrosive gases (ISA G3 compliant)
• USB Port: Full-speed USB 2.0 for local programming and firmware updates
• Status Indicators: RUN, FORCE, SD (safety disabled), SF (safety fault), I/O status, and USB activity LEDs

System Integration & Compatibility

• Primary Platform: ControlLogix 1756 chassis
• Safety Partner: 1756-L7SP (required for SIL 3 / PLe in adjacent slot)
• Safety I/O Modules: 1756-LSC8XIB8I, POINT Guard I/O, FLEX 5000 Safety I/O
• Communication Modules: 1756-EN2T, 1756-EN3TR, 1756-CN2R, 1756-DNB
• Compatible Chassis: 1756-A4, 1756-A7, 1756-A10, 1756-A13, 1756-A17
• Software Version: Studio 5000 Logix Designer v20 or later with GuardLogix safety license
• Related Parts: 1756-L73S (non-coated), 1756-L73SXT (Xtreme temperature), 1756-L72SK (4 MB + 2 MB safety), 1756-L71SK (2 MB + 1 MB safety)

Environmental & Operational Limits

• Operating Temperature: 0°C to 60°C (32°F to 140°F)
• Storage Temperature: -40°C to +85°C (-40°F to 185°F)
• Humidity: 5% to 95% RH, non-condensing
• Vibration: 2G, 10 to 500 Hz
• Shock: 30G operating; 50G non-operating
• Approvals: TÜV Rheinland certified for SIL 3 / PLe, UL, cUL, CE, ATEX, RoHS

Industrial Applications

Widely deployed in oil & gas platforms, high-availability process systems, pharmaceutical manufacturing, automotive assembly lines, safety-critical material handling, burner management systems, and emergency shutdown (ESD) applications requiring fault-tolerant safety control in harsh environments.

Frequently Asked Questions

What is the difference between 1756-L73S and 1756-L73SK?

The 1756-L73S is the standard GuardLogix safety controller with 8 MB + 4 MB safety memory. The 1756-L73SK adds conformal coating for enhanced protection against moisture, dust, and corrosive gases in harsh industrial environments. All other specifications are identical.

Do I need a safety partner module?

For SIL 3 / PLe applications, the 1756-L7SP safety partner module is required in the slot immediately to the right of the controller. Without the L7SP, the controller operates at SIL 2 / PLd.

What does the conformal coating protect against?

The conformal coating protects the controller's circuit boards from moisture, dust, and corrosive gases (ISA G3 rated), making it suitable for chemical plants, offshore platforms, and other harsh industrial environments.

What is the difference between 1756-L73SK and 1756-L73SXT?

The 1756-L73SK has conformal coating for harsh environments (0°C to 60°C). The 1756-L73SXT is an Xtreme Temperature variant rated for -20°C to +70°C with conformal coating.

What are the related part numbers?

• 1756-L71SK — GuardLogix 5570, 2 MB + 1 MB safety, conformal coated
• 1756-L72SK — GuardLogix 5570, 4 MB + 2 MB safety, conformal coated
• 1756-L73S — GuardLogix 5570, 8 MB + 4 MB safety, standard
• 1756-L73SK — GuardLogix 5570, 8 MB + 4 MB safety, conformal coated (this part)
• 1756-L73SXT — GuardLogix 5570, 8 MB + 4 MB safety, Xtreme temperature
• 1756-L7SP — Safety Partner Module (required for SIL 3 / PLe)