When the Line Needs a Brain That Speaks Ethernet
A mid-size oil and gas skid builder was integrating machine-level control with plant-wide data collection. The existing processor had no native Ethernet, so every data pull required third-party converters and extra panel space. The fix was the Allen-Bradley 1747-L552, an SLC 5/05 processor that plugs directly into any SLC 500 chassis backplane and brings embedded Ethernet out of the box.
What the 1747-L552 Actually Is
The 1747-L552 is a single-slot SLC 5/05 processor module from Allen-Bradley. It carries up to 32 KB of battery-backed RAM, a 9-pin RS-232 port and Ethernet communication ports. Because the Ethernet connection is native, this processor is ready for vertical integration without specialty modules or third-party gateways. That makes it practical for medium to large applications that need machine-level control tied to enterprise-level data.
Key Parameters That Matter on the Floor
Memory and Program Capacity
With up to 32 KB of battery-backed RAM, the 1747-L552 handles multiple small processes or one large process. The battery backup uses the 1747-BA, and a capacitor keeps the processor running at least 30 minutes if the battery is disconnected. Reconnect within that window to avoid losing RAM data.
I/O and Chassis Reach
This processor controls up to 4096 discrete inputs and 4096 discrete outputs, with 480 analog I/O points. It supports up to three I/O chassis with a maximum of 30 slots, and it permits Remote I/O topology for strategic module placement.
Communications
The RS-232 port suits HMI communication on the same panel, where cable distance is short. Ethernet handles networked applications and simultaneous data exchange, supporting up to 48 incoming or outgoing connections. Outgoing connections allow one connection per destination node; multiple MSG instructions to the same node share that connection.
Environmental and Physical
Operating temperature runs 0 to 60 degrees Celsius, with storage from -40 to 85 degrees Celsius. Relative humidity is 5 to 95 percent, non-condensing. The open-type enclosure mounts via chassis and measures 145 x 35 x 142 millimeters.
Where It Fits in Oil, Gas and Automation
In a gas compression station, the 1747-L552 can run local control while pushing performance data over Ethernet to a historian. On a water treatment skid, the RS-232 port drives a panel HMI while Ethernet feeds the SCADA layer. For a packaging line upgrade, the 4096-point I/O capacity lets one processor manage several small processes without adding hardware.
Integration Notes
The embedded Ethernet makes vertical integration straightforward, but the DH485, Data Highway Plus, Remote I/O and DeviceNet protocols are proprietary and require specialty modules or third-party converters and gateways. Confirm cables and gateways with your supplier before wiring into those networks.
Maintenance and Reliability
The status LEDs let you monitor the processor state at a glance. Power must be turned off when adding or removing a module. The user-replaceable lithium battery lasts an average of two years; track that interval to protect program memory. Please verify current lifecycle status and availability with Oil AutoTech before ordering.
Selection Checklist
Before you buy, confirm your chassis type, required I/O count, and whether you need Remote I/O. The 1747-L552 pairs with the 1747-BA battery and 1747-M13 backup memory. For hands-on technical selection help and fast dispatch, worldwide, contact Oil AutoTech today for pricing and availability.
