Allen-Bradley 1756-L72S ControlLogix Processor 4 MB – Pickup in Store
In stock: 1 unit in Milwaukee, WI. Physically stocked and ready to ship or available for local pickup. Includes a 1-year full-function warranty.
4 MB GuardLogix 5570 safety controller
Actual NJT inventory photos
Price
$749.99USDUsed, Series BView listing
| Part Number | 1756-L72S |
| Description | GuardLogix 5570 safety controller, 4 MB. In stock in used condition, Series B. |
| Shipping | Ships same or next business day
|
| Pickup | Free local pickup at 2122 N Prospect Ave. Call ahead at (414) 331-5954. |
| Warranty | 1-year full-function warranty provided by NJT Automation. Warranty details
|
| Returns | 90-day free returns. View return policy |
| Exchange | Send us your defective 1756-L72S after your purchase for a 10% core credit. We also purchase old or damaged parts outright. |
Replacement Options for 1756-L72S
| Variants | Part NumberConditionSeriesQtyPrice 1756-L72S /B$749.99 Used · Series B · 1 in stock1756-L72S /BUsedSeries B1$749.99 USD | ||||||||
| Availability | 1 unit in stock | ||||||||
| Repairs | 1756-L72S Mail-In Repair ServiceEstimated: $1,440.00 | ||||||||
Part Number Decoder | GuardLogix 5570 safety controller 1756L72S
Decoded from the Rockwell Automation catalog-number structure. Series and firmware revision are printed on the product label, not encoded here. | ||||||||
Series & Revisions | Series B in stock; other series on request. All series use the 1756-ESMCAP energy-storage module and a 1784-SD1 / SD2 card; no battery. Series notes: Studio 5000 keys on catalog number and firmware revision, not series. | ||||||||
Intended Use | Intended for plant-wide discrete, process, and motion control applications. ControlLogix controllers run high I/O-count machines, batch and continuous process lines, and coordinated multi-axis motion from a single chassis, with redundancy and plant-network connectivity when the application calls for it. Typical homes are automotive and tire plants, food and beverage lines, water and wastewater, oil and gas skids, and large packaging systems. Safety-rated for use in GuardLogix safety chains up to SIL 3 / PLe. | ||||||||
Physical Data | Weight and DimensionsWeight0.87 lb (0.39 kg)H × W × D5.7 × 1.4 × 5.7 in. (145 × 35 × 145 mm)
Product weight and dimensions are typical manufacturer-published values and may differ by series or option. Shipping box and weight are estimates for freight planning; the packed unit may ship in a different box. | ||||||||
| Category | ControlLogix | ||||||||
| Part Number | 1756-L72S | ||||||||
| Manufacturer | Allen-Bradley | ||||||||
Image gallery6 PHOTOSActual units photographed by NJT
Can the 1756-L72S be repaired?
Yes. NJT Automation repairs the 1756-L72S by mail-in: diagnostic evaluation, component-level repair and a functional test, backed by a 1-year full-function warranty.
Option 1
NJT managed repair
- Evaluation
- Free. No repair, no charge.
- Shipping
- Prepaid UPS label both ways.
- Pricing
- $650 minimum. Rush service available.
- Warranty
- 1-year full-function warranty included; 2- and 3-year options.
Option 2
Independent repair bids. Compare quotes from independent repair technicians. Post your repair on RepairMode to receive competitive bids from experienced technicians. Each technician sets their own pricing and warranty.
Common Failures
Failure patterns we regularly see on GuardLogix 5570 safety controller hardware like the 1756-L72S:
- SD card corruption preventing the stored project from loading at power-up
- Front USB port failure: Studio 5000 will not connect over USB
- Scrolling status display blank or unreadable
- Backplane communication faults from bent chassis pins after repeated module swaps
- Program lost on power cycle: energy storage module (1756-ESMCAP / ESMNSE) failing to hold the controller through a save
Fault code reference
1756-L72S Fault Codes
42 codes · 1756-RD001
Fault codes a GuardLogix 5570 safety controller reports on the Major Faults tab in Studio 5000 Logix Designer / RSLogix 5000 as Type:Code (T:C), as documented in Rockwell Automation publication 1756-RD001. Use them to narrow a problem down to the unit, its wiring or the application before sending it in for repair.
| Code | Fault | What it indicates |
|---|---|---|
| T01:C01 | Power-up fault | Power was lost and restored while the controller was in RUN mode. |
| T01:C16 | Power-up fault | I/O communications configuration fault detected at power-up. |
| T01:C40 | Power-up fault | Energy storage module or battery failed during the last power-down; retained data may be lost. |
| T01:C60 | Power-up fault | Non-recoverable fault. The controller must be reflashed or returned for repair. |
| T01:C61 | Power-up fault | Non-recoverable fault with saved diagnostic information. |
| T01:C62 | Power-up fault | Non-recoverable fault with saved diagnostic information and stored user program. |
| T03:C16 | I/O fault | An I/O module connection failed on a module marked as required. |
| T03:C20 | I/O fault | Unable to read ControlBus chassis information; the chassis may be bad. |
| T03:C21 | I/O fault | Unable to read ControlBus chassis information; the chassis may be bad. |
| T03:C23 | I/O fault | At least one required connection was not established before going into RUN mode. |
Show 32 more codes
| T04:C16 | Program fault | Unknown instruction encountered. |
| T04:C20 | Program fault | Array subscript too large, or CONTROL data type POS or LEN invalid. |
| T04:C21 | Program fault | CONTROL data type LEN or POS less than 0. |
| T04:C24 | Program fault | Unknown data type passed to a subroutine. |
| T04:C31 | Program fault | JSR or RET did not pass as many parameters as expected. |
| T04:C34 | Program fault | A timer instruction had a negative value for its PRE or ACC. |
| T04:C42 | Program fault | JMP to a label that did not exist or was deleted. |
| T04:C82 | Program fault | Could not re-enter an executing SFC routine. |
| T04:C83 | Program fault | Value out of range. |
| T04:C84 | Program fault | Stack overflow: stack too small to perform the operation. |
| T04:C85 | Program fault | Invalid routine type. |
| T04:C89 | Program fault | Target step does not exist in the specified routine. |
| T04:C90 | Program fault | A safety instruction occurs outside a safety task. |
| T04:C91 | Program fault | Equipment phase instruction cannot be called from a program. |
| T04:C94 | Program fault | Nesting limits exceeded. |
| T04:C990–C999 | Program fault | User-defined major fault raised by the application. |
| T06:C01 | Watchdog fault | Task watchdog expired: an infinite loop, an over-complex program or a higher-priority task starved the task. |
| T07:C40 | Nonvolatile fault | Store to nonvolatile memory (CompactFlash / SD) failed. |
| T07:C41 | Nonvolatile fault | Load from nonvolatile memory failed: controller type mismatch. |
| T07:C42 | Nonvolatile fault | Load from nonvolatile memory failed: controller revision mismatch. |
| T07:C43 | Nonvolatile fault | Load from nonvolatile memory failed: bad checksum. |
| T07:C44 | Nonvolatile fault | Failed to restore processor memory. |
| T07:C50 | Nonvolatile fault | Security certificate invalid. |
| T08:C01 | Mode change fault | Mode change inhibited because a download is in progress. |
| T11:C01 | Motion fault | Actual position of the axis exceeded the positive overtravel limit. |
| T11:C02 | Motion fault | Actual position of the axis exceeded the negative overtravel limit. |
| T11:C03 | Motion fault | Actual position exceeded the position error tolerance. |
| T11:C04 | Motion fault | Encoder channel A, B or Z connection failed. |
| T11:C05 | Motion fault | Encoder noise event detected, or encoder signals not in quadrature. |
| T11:C06 | Motion fault | Drive fault reported by the servo drive. |
| T11:C07 | Motion fault | Synchronous connection to the servo module failed. |
| T11:C08 | Motion fault | Hardware failure in the servo module. |
Where the manual's only remedy for a code is to replace the unit or module, the code is pointing at a hardware fault inside that part. Those are the faults NJT Automation repairs at component level, so a repair quote is usually the first thing to check before buying a replacement.
Source: Rockwell Automation publication 1756-RD001, Logix 5000 Controller and I/O Fault Codes. Codes are listed as documented; fault behaviour can vary by firmware revision, so confirm against the manual for your unit's series.
Photos by NJT Automation; test videos from NJT or network repair technicians.
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