Product Description
The Allen-Bradley 1756-L55M12 ControlLogix 5555 controller features 750 KB of memory for data and logic and 208 KB of I/O memory, but lacks nonvolatile memory. This open-style controller, weighing 0.35 kg (12.5 oz), supports ControlNet, EtherNet/IP, DH+, DeviceNet, and universal remote I/O communication networks. It draws 1.23 A at 5.1V DC and 0.014 A at 24V DC from the backplane, with a power dissipation of 5.6W and thermal dissipation of 19.1 BTU/hr. It offers 10V rms conducted RF immunity and 30V continuous isolation voltage, tested to withstand 707V DC for 60 seconds. It uses a 1756-BA1 lithium battery (0.59 g), replaceable only when necessary, and utilizes wiring category 2 communication ports compatible with 1756-CP3 or 1747-CP3 serial cables. This controller, along with other 1756-L55 models, can be implemented in a redundant ControlNet system. Its operating temperature range is 0-60C, with a storage range of -40-85C and a noncondensing relative humidity of 5-95%. It withstands an operating shock of 30 g, a non-operating shock of 50 g, and vibration of 2 g at 10-500 Hz.
Is Your Device Showing These Signs?
The Allen Bradley 1756-L55M12 ControlLogix controller commonly experiences issues such as corrupted firmware requiring a firmware upgrade, backplane communication failures due to a faulty chassis or power supply, memory module errors causing program faults, and CPU faults stemming from excessive I/O loading or program logic errors. Resolve these issues through firmware reflashing, backplane inspection and replacement, memory module replacement, and code optimization to reduce CPU utilization and I/O demands. Address power supply problems by verifying voltage levels and replacing the power supply if necessary.
Technical specifications
The Allen-Bradley 1756-L55M12 ControlLogix 5555 controller is an open-style controller with 750 KB of memory for data and logic and 208 KB of I/O memory, but no nonvolatile memory. It supports various communication networks, has specific power consumption and dissipation characteristics, and offers RF immunity and isolation voltage protection. It uses a replaceable lithium battery and is compatible with specific serial cables. It can be used in a redundant ControlNet system and has defined operating and storage temperature ranges, humidity limits, and shock/vibration resistance.
Our Repair Process for the
1756-L55M12
Our repair process for the Allen Bradley 1756-L55M12 ControlLogix controller begins with a comprehensive diagnostic assessment to pinpoint the root cause of the failure. Firmware corruption necessitates a complete firmware reflashing to restore proper operation. Backplane communication failures require a thorough inspection of the chassis and power supply; replace any faulty components immediately. Memory module errors demand the immediate replacement of the defective module. CPU faults resulting from excessive I/O loading or program logic errors are resolved through rigorous code optimization to reduce CPU utilization and I/O demands. Power supply problems are addressed by verifying voltage levels and replacing the power supply if it fails to meet specifications.
Your Guarantee: Warranty & Lifetime Support
Your satisfaction is our top priority, and we confidently stand behind the quality of our repairs. That's why every repair service is covered by our comprehensive 24-month warranty. Furthermore, we offer lifetime phone support – if you have questions or need assistance related to our repair down the road, we're here to help. Our service commitment is straightforward: we guarantee our work, and if you're not satisfied, we will make it right. Learn More about our Repair process.
Comprehensive Repairs You Can Depend On
We take immense pride in the quality and reliability of our work. Our process goes beyond simply fixing the immediate problem. We perform a comprehensive inspection of your main board (or other equipment) and proactively replace components known to be failure-prone or showing signs of potential future failure. Before any item is returned, it undergoes rigorous functional testing to ensure it meets performance specifications and operates flawlessly. Visit our main Repair Services page to learn more.
Save Significantly
Our primary goal is to save you hundreds, or even thousands, of dollars compared to the cost of new equipment replacement. By repairing existing components, we provide an economical solution that is also eco-friendly. At Roc Industrial, our commitment to integrity and community drives our consistent growth and ensures you receive a reliable, cost-effective solution.

Please Note: Roc Industrial operates as an independent service provider and is not an authorized distributor for the manufacturers or brands mentioned. Consequently, the original manufacturer's warranty is not applicable to items repaired or sold by us. Roc Industrial provides its own 2-year warranty on all repair services performed.

















