Allen-Bradley 1752-L24-24AWA SmartGuard 600 Safety Controller

The 1752-L24-24AWA is a standalone safety controller from Allen-Bradley, part of the Rockwell Automation SmartGuard 600 family. It is a self-contained safety system, not merely an I/O module: the controller runs a safety program locally, makes the safety decision, and drives the outputs without depending on a main PLC scan. The 1752-L24-24AWA provides 24 safety I/O points in a compact housing — 8 safety inputs, 4 solid-state safety outputs, and 4 configurable safety I/O points that can be assigned as inputs or outputs in the configuration software. Inputs accept single or dual-channel devices and are rated up to 24 V DC at 4 A, with an OFF-state current of less than 1.3 mA.

The architecture of the 1752-L24-24AWA is built around scalability. A single controller can support up to 128 safety I/O points when paired with expansion modules, and up to 16 of those points can be safety outputs. The expansion I/O is connected over a dedicated expansion cable rather than a network, which keeps the safety communication deterministic and separate from the plant Ethernet. The 1752-L24BBE is the expansion module in this family: it adds 24 safety I/O points of its own — 8 safety inputs and 16 safety outputs — and it is the module that lets a 1752-L24-24AWA-based system grow from a single machine to a more capable safety cell without changing the controller or the safety program structure.

Programming and configuration of the 1752-L24-24AWA are done in RSLogix 5000 (version 16.03.00 and later) and Studio 5000 Logix Designer (version 21.00.00 and later) with the 1752-L24-AWA Add-On Profile. Safety functions are configured with function blocks rather than relay logic, and the safety program is password protected, so only authorized personnel can modify the safety logic. The 1752-L24-24AWA also carries an RS-232 serial port and a DeviceNet port, the latter supporting DeviceNet Safety so the controller can sit on a DeviceNet network and exchange safety data with other safety devices.

Description

Technical Specifications

Parameter Name	Parameter Value
Product Model	1752-L24-24AWA (controller); 1752-L24BBE (expansion I/O)
Manufacturer	Rockwell Automation / Allen-Bradley
Product Type	SmartGuard 600 Standalone Safety Controller / Safety I/O Expansion Module
Product Family / Platform	Bulletin 1752 SmartGuard 600
Safety I/O Points	24 (8 inputs, 4 solid-state outputs, 4 configurable I/O)
Expansion Module Points	24 (8 safety inputs, 16 safety outputs)
Maximum System Safety I/O	128 points; up to 16 safety outputs
Input Voltage	24 V DC
Input Current Rating	4 A
Input OFF-State Current	Less than 1.3 mA
Input Channel Type	Single-channel or dual-channel (2 input channels per 1 safety input)
Output Type	Solid state
Output Voltage	24 V DC
Output Current	0.5 A
Output Fusing	2 A
Output Leakage Current	1.3 mA
Output ON Voltage Drop	2.5 V at 0.5 A
Output Surge Current	4 A for 10 ms
Reaction Time	12 ms typical
Cycle Time	7 ms
Internal Relay (wetting voltage)	24 V DC, 0.1 A, 0.25 A surge for 10 ms
Power Supply Input	24 V DC, 8 W
Power Dissipation	8 W
Thermal Dissipation	27.3 BTU/hr
Communication Ports	RS-232 serial; DeviceNet (DeviceNet Safety capable)
Expansion Connection	Expansion I/O cable to 1752-L24BBE modules
Programming Software	RSLogix 5000 v16.03.00+; Studio 5000 Logix Designer v21.00.00+
Safety Program Protection	Password protected
Enclosure Type Rating	None (open-style)
Dimensions (controller)	3.7 x 4.1 x 2.8 in (93.7 x 103.1 x 70.4 mm)
Dimensions (expansion module)	3.7 x 4.1 x 2.1 in (93.7 x 103.1 x 53.6 mm)
Weight	0.64 lb (0.29 kg)
Operating Temperature	0 to 55 °C (32 to 131 °F)
Storage Temperature	-40 to 85 °C (-40 to 185 °F)
Relative Humidity	5 to 95%, non-condensing
Certifications	CE, CSA, C-UL, FM, ATEX, IECEx, RCM, CCC, EAC, KC
Lifecycle Status	Active

Main Features and Advantages

A standalone safety decision, not a dependent module:

The 1752-L24-24AWA runs the safety program on board and drives its outputs directly, so the safety function does not wait for a main controller scan or depend on the main PLC being healthy. This is the defining advantage of a standalone safety controller over a safety I/O module: the safety logic continues to execute and the outputs continue to be driven correctly even if the main controller is faulted, updating, or offline.

Function-block safety logic with password protection:

Rather than asking engineers to reproduce safety functions in ladder, the 1752-L24-24AWA configures safety through dedicated function blocks in RSLogix 5000 and Studio 5000 Logix Designer. Emergency stop, two-hand control, muting, safety mat, and lockout functions are assembled from tested building blocks, and the safety program is password protected so unauthorized changes cannot be made on the floor. This both reduces engineering effort and strengthens the change-control discipline that safety systems require.

Dual-channel input architecture:

Each safety input on the 1752-L24-24AWA uses two input channels, so a single-field device such as an emergency-stop button or a safety gate switch is monitored for both contacts. A discrepancy between the two channels is treated as a fault, which is how the controller detects a welded contact, a broken wire, or a defeated switch. The result is a safety input that fails toward a known, safe state rather than silently degrading.

Scalable to 128 safety I/O without changing platforms:

The 1752-L24-24AWA supports up to 128 safety I/O points across the controller and its 1752-L24BBE expansion modules, with up to 16 safety outputs. The expansion connection uses a dedicated cable rather than a network, so adding points does not consume DeviceNet or Ethernet bandwidth and does not introduce network latency into the safety reaction time. For machine builders, this means one controller family covers a small single-cell machine and a larger multi-cell line.