Product Overview
The Allen-Bradley 1747-L551 is an SLC 5/05 series processor module built for control engineers who need dependable logic execution without a complicated setup. As a maintenance engineer, you want a processor that starts fast, communicates clearly, and tells you when something is wrong. This module does exactly that.
It installs exclusively in Slot Zero of an SLC 500 chassis and supports up to 4096 inputs and 4096 outputs. With 16 KB of battery-backed RAM, the 1747-L551 keeps your program intact through power interruptions. The built-in real-time clock and calendar add time-stamping capability for event logging.
Key Specifications
Memory and Scan Performance
The 16 KB user memory (16,000 words) handles mid-size control programs comfortably. A typical program scan time of 0.9 ms/K and I/O scan time of 0.225 milliseconds keep machine cycles tight. Battery backup uses the 1747-BA battery, and the 1747-M13 memory module can expand backup capacity up to 64K.
Communication and Integration
The integrated 10/100 Base-T Ethernet port supports SNMP, BOOTP, and extended messaging. The RS-232 channel handles DF1 full-duplex, DF1 half-duplex master, and DF1 radio modem communication. Supported protocols include Ethernet, Remote I/O (RIO), DH485, and Data Highway Plus (DH+).
Environmental Durability
Operating temperature ranges from 0 to 60 degrees Celsius. The module withstands 30G operating shock and 2.5G vibration at 5 to 2000 Hertz. Isolation between communication circuits is rated at 500 Volts DC, and backplane-to-I/O isolation is 1500 Volts AC.
Maintenance and Reliability
The 1747-L551 is built for serviceability. Its LED indicators show run status, CPU faults, low battery, forced I/O, and Ethernet/RS-232 port activity. A quick glance tells you whether the processor is healthy or needs attention.
For preventive maintenance, inspect the battery periodically and replace it before it fails. Keep the chassis clean and ensure ambient temperature stays within the 0 to 60 degrees Celsius range. The 30G shock rating means the module tolerates typical panel vibration, but mounting hardware should still be checked during scheduled downtime.
When you need spares fast, Oil AutoTech provides ready-to-ship modules for oil, gas, and industrial automation applications. Contact Oil AutoTech today for pricing and availability.
Frequently Asked Questions
What communication ports does the 1747-L551 have?
It includes a built-in 10/100 Base-T Ethernet port and an RS-232 port supporting DF1 full-duplex, DF1 half-duplex master, and DF1 radio modem protocols.
How much memory does the 1747-L551 support?
The module has 16 KB of battery-backed RAM (16,000 words). With the 1747-M13 memory module, backup capacity can reach 64K.
Where does the 1747-L551 install in the chassis?
It must be installed in Slot Zero (0) of the SLC 500 chassis.
What is the program scan time?
The typical program scan time is 0.9 milliseconds per keyword, with an I/O scan time of 0.225 milliseconds.
Can the 1747-L551 connect to HMI and SCADA systems?
Yes. It supports communication with computer-based control systems including Human Machine Interface (HMI) and Supervisory Control and Data Acquisition (SCADA).
