The Allen-Bradley PLC-5-40L is a Standard PLC-5 Processor. It has versatile built-in communication options for peer-to-peer communication. For communication, it has 2 DH+ or Remote I/O (Adapter or Scanner) ports, 1 Extended Local I/O port and 1 serial port configurable for RS-232 / RS-423 / RS-422A communications. A remote I/O connection features real-time data exchange between I/O processors and modules, operator interface, and other host computers. The PLC-5-40L uses Ladder-logic and structured-text programming with advanced instruction sets including sequencer, file-handling, diagnostic, immediate I/O, shift register, and program control instructions. It offers flexible, cost-effective connections to a wide range of devices.

The PLC-5-40L processor has maximum user memory of 48K words with a limit of 32K words per data table file. It has up to 2048 total I/O (any number of I/O can be inputs or outputs) with 2048 complementary inputs and outputs. It has 16 (0 – 17) I/O racks for I/O addressing. It has an I/O scan time per rack of 0.5ms for extended local I/O, 10ms at 57.6 kb/s, 7ms at 115.2 kb/s, and 3ms at 230.4 kb/s. It requires a backplane current of 3.3A at 5V and it has a maximum power dissipation of 17.3W. The PLC-5-40L also contains a battery-backed static RAM with an EEPROM program backup option. It is installed in the left-most slot of the 1771 I/O chassis and requires one slot.

The PLC-5-40L processor has global status flags and input interrupts. It has programmable fault response diagnostics which prevent system failure by reacting to the faults. It allows for segregation of tasks controlled by multiple main programs. The PLC-5-40L examines specific information at specific time intervals with the time-interrupt routine.