Purchase now: Allen Bradley 1747-L551 SLC 5/05 Processor
Purchase now: Atlantechdrives provides you the 1747-L551, a revolutionary CPU processor from the Allen Bradley SLC 5/05 family. The SLC 5/05 series fundamentally transformed industrial automation by replacing legacy DH-485 or DH+ networks with a native Ethernet/IP port (10/100 Mbps). Equipped with 16,000 words (16K) of user memory, the 1747-L551 allows your factory floor to seamlessly integrate with modern IT infrastructure. This enables high-speed data acquisition, direct SCADA polling over standard TCP/IP networks, and remote programming from anywhere in the facility without requiring expensive proprietary adapters. It is the perfect upgrade for medium-scale manufacturing systems looking to step into modern networking while retaining their reliable 1746 chassis hardware.
Technical Specifications of the 1747-L551
The 1747-L551 utilizes the standard slot 0 position in any SLC chassis. It provides lightning-fast execution times and dual communication ports, bridging the gap between legacy serial devices and modern Ethernet architectures.
- Part Number: 1747-L551
- Processor Class: SLC 5/05 CPU
- Total User Memory: 16K Words (Instructions and Data)
- Channel 1 Port: Ethernet/IP (RJ45, 10/100 Mbps)
- Channel 0 Port: RS-232 (Supports DF1, ASCII, DH-485 via adapter)
- Maximum Local I/O Capacity: 4096 inputs / 4096 outputs
- Maximum Local Chassis: 3 (Up to 30 slots total)
- Backplane Current Draw: 1.0 Amps at 5V DC
Expert Installation Advice: The BOOTP/DHCP Trap
Setting up the Ethernet port on a brand new or factory-reset 1747-L551 catches many technicians off guard. Expert Tip: Out of the box, the processor does not have a default IP address. It is set to broadcast a BOOTP (Bootstrap Protocol) request. You must use the Rockwell BOOTP-DHCP Server utility on your laptop to intercept the processor’s MAC address and assign it an IPv4 address. Critical Step: Once you assign the IP address and successfully ping the PLC, you must use RSLinx to right-click the processor, go to Module Configuration, and uncheck the «BOOTP Enable» box, forcing it to a Static IP. If you forget to disable BOOTP, the processor will lose its IP address the moment the cabinet power is cycled, taking the machine completely offline.
Maintenance and Network Security
Because the 1747-L551 utilizes standard Ethernet, it is susceptible to the same IT hazards as office computers. Never plug the SLC 5/05 directly into an unmanaged corporate IT network or expose it to the public internet. Excessive broadcast traffic (ARP requests, general network chatter) from office computers can overwhelm the processor’s ethernet chip, causing «Network Storms» that will crash the PLC and halt production. Always install this processor behind an industrial managed switch or a dedicated VLAN specifically isolated for plant floor automation.
Frequently Asked Questions (FAQs)
Q: Can I use the RJ45 port on the 1747-L551 for DH-485 communication?
A: No. Unlike the older SLC 5/01, 5/02, or 5/03 processors, the RJ45 port on the 5/05 is strictly an Ethernet/IP port. Plugging it into a legacy DH-485 network hub (like an AIC+) will cause severe electrical damage to the port.
Q: Does the 1747-L551 support Online Editing?
A: Yes. You can securely connect over Ethernet using RSLogix 500 and perform online programming edits, forcing, and real-time monitoring while the machine continues to operate.
Do you need more references from this brand? Explore our full catalog of Allen Bradley here.
The SLC 5/05 16KB CPU adds modern Ethernet/IP capabilities to your legacy 1746-A7 modular system.
