The Allen-Bradley 1756-L74 is a ControlLogix 5570 series programmable automation controller (PAC), positioned as a high-end model in Rockwell Automation's flagship Logix platform. The controller includes a built-in USB programming port, ships with a 1 GB Secure Digital (SD) card for non-volatile storage, and uses a removable Energy Storage Module (ESM) instead of a lithium battery for maintenance-free operation.
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Item No :
1756-L74Order(MOQ) :
1 PiecePayment :
EXWProduct Origin :
USAShipping Port :
WuhanLead Time :
3~5 daysWeight :
3kg| Specification | Description |
|---|---|
| Manufacturer | Rockwell Automation (Allen-Bradley) |
| Model | 1756-L74 |
| Product Family | ControlLogix 5570 |
| Product Type | Programmable Automation Controller (PAC) |
| User Memory | 16 MB |
| I/O Memory | 0.98 MB |
| Non-Volatile Memory | 1 GB SD card included (1784-SD1); expandable to 2 GB (1784-SD2) |
| Built-in Communication Port | 1 x USB 2.0 (programming only) |
| Optional Communication | EtherNet/IP, ControlNet, DeviceNet, DH+, Remote I/O, SynchLink via separate modules |
| Max Digital I/O | 128,000 points |
| Max Analog I/O | 4,000 points |
| Controller Tasks | 32 tasks; 100 programs/task (1,000 with Logix Designer v24+) |
| Programming Languages | Ladder Diagram (LD), Structured Text (ST), Function Block Diagram (FBD), Sequential Function Chart (SFC) |
| Energy Storage Module | 1756-ESMCAP pre-installed; compatible with 1756-ESMNSE, 1756-ESMNRM |
| Backplane Current Draw | 800 mA @ 5.1V DC; 5 mA @ 1.2V DC |
| Power Dissipation | 2.5 W |
| Thermal Dissipation | 8.5 BTU/hr |
| Isolation Voltage | 30V continuous (USB port) |
| Module Location | Any slot in 1756 ControlLogix chassis (A4, A7, A10, A13, A17) |
| Slot Width | 1 |
| Weight | Approx. 0.6 kg (1.31 lbs) |
| Operating Temperature | 0°C to +60°C |
| Certifications | UL, c-UL-us, CE, CSA, FM, ATEX, TÜV |
| Lifecycle Status | Active Mature (5570 series, still supported) |
| Model | User Memory | Description |
|---|---|---|
| 1756-L71 | 2 MB | Entry-level 5570 controller |
| 1756-L72 | 4 MB | Low mid-range 5570 controller |
| 1756-L73 | 8 MB | Mid-range 5570 controller |
| 1756-L74 (this model) | 16 MB | High-end 5570 controller |
| 1756-L75 | 32 MB | Flagship 5570 controller |
| 1756-L73S | 8 MB + 4 MB safety | GuardLogix safety controller |
| 1756-L74K | 16 MB | Conformal-coated version for harsh environments |
| 1756-L75K | 32 MB | Conformal-coated flagship version |
| 1756-L81E | 3 MB | Entry-level 5580 controller (built-in Ethernet) |
| 1756-L82E | 5 MB | Mid-range 5580 controller (built-in Ethernet) |
| 1756-L83E | 10 MB | Upper mid-range 5580 controller (built-in Ethernet) |
Q1: What is the primary function of the 1756-L74?
It is a high-end ControlLogix 5570 programmable automation controller that serves as the central processing unit for industrial automation systems. It executes user logic, manages I/O communication, and supports process, motion, and discrete control applications in manufacturing and process industries.
Q2: Does the 1756-L74 have a built-in Ethernet port?
No. Unlike the newer 5580 series (which features built-in 1 Gb Ethernet), the 5570 series controllers like the 1756-L74 require a separate communication module (such as 1756-EN2T, 1756-ENBT, or 1756-EN3TR) installed in the chassis for network connectivity. The controller itself has only a USB programming port.
Q3: Can the 1756-L74 be used in a redundant (ControlLogix Redundancy) system?
Yes. The 1756-L74 supports full controller redundancy when paired with the 1756-RM2 redundancy module and a second identical controller. This provides hot-standby capability for high-availability applications in process industries such as chemical, oil & gas, and water/wastewater.
Q4: What is the Energy Storage Module (ESM) and why is it important?
The ESM is a capacitor-based module (1756-ESMCAP) that replaces traditional lithium batteries for retaining RAM contents during power cycles. It eliminates battery maintenance and environmental disposal issues associated with lithium batteries. The ESM is removable and replaceable, and the controller ships with one pre-installed.
Q5: What software is required to program the 1756-L74?
The controller is programmed using Studio 5000 Logix Designer (formerly RSLogix 5000). The 1756-L74 supports firmware revisions from v19 through v31 according to Rockwell's compatibility matrix . It is compatible with a wide range of Logix Designer versions depending on the specific firmware revision in use.
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