The Allen-Bradley 1747-L531 is an SLC 5/03 processor type module that belongs to the SLC 500 Modular Hardware Style series. It is built to perform a large variety of functions, including small, simple stand-alone systems to large, complex distributed ones. Designed to perform throughput, it can support 60 various I/O modules including analog, digital, and intelligent I/O’s and can, in addition, control up to 4,096 output and input points. It ships with the SLC 500 modular processor, a compatible chassis, power supplies, and installation instructions for all the included parts. This module is C-Tick marked, CE compliant, and UL listed to Canadian and US Safety Standards,

The 1747-L531 Modular Processor comes with a memory size of 8 K, 16 K, or 32 K for its programs. This user-configurable memory can be applied either to program storage or to data storage. The drive features a battery-backed RAM that lasts approximately 2 years. The BATT LED indicator alerts user when the voltage of the replaceable battery has fallen below the threshold level. A minimum of thirty (30) minutes of power is available when the battery is disconnected, due to an integrated capacitor. If a new battery is installed to replace the old one within half an hour (30 minutes), any data stored in the RAM can be retained. The 1747-L531 Processor receives and initiates communication protocols including DH-485 peer-to-peer, ControlNet, Ethernet, Data Highway Plus (DH+), DeviceNet, Modbus RTU Master, as well as full-duplex or half-duplex master or slave DF1, ASCII and DH-485 via the RS232 port. Its front panel has a 3-position key switch that allows three operation modes: PROGRAM, RUN, and REMOTE. This key switch cannot be used in place of an emergency-stop switch or a hardwired master control relay.

This controller has an integrated 8K memory, which can be expanded with the use of a Flash EPROM. The required memory module has part number of 1747-M13 and adapter socket of 1747-M15 that supports up to 64K of user memory. User program can be stored or burned to the memory module to prevent accidental or unwanted program deletion that may be caused by improper programming, electrical surges and noises. The general rule when burning user program to the memory module is that the program size must not exceed the processor memory size. Do not burn a faulted program, especially a program with a major fault. This will include the fault condition and cause of the fault to be burned in the EPROM.

User programs, hardware configuration are implemented here as well as commissioning and troubleshooting tool are available such as I/O forcing.

This processor also supports hold-up time feature. This refers to the processor’s ability to continue programming scanning for a limited time even if the input voltage to the system power supply falls below the nominal range. When the hold-up time expire, the CPU is automatically put to stop mode. This prevents sudden stoppage that is not ideal in any control application.