The 1747-L542 SLC is an SLC 5/03 controller. This controller is one of the Three (3) controllers under the 1747-L52 SLC 5/03 category. This controller is the mid-range controller of SLC 5/03 which has 32 KB user memory while still capable of handling 4096 Input and outputs.
The 1747-L542 is used with the modular style hardware. This processor is installed to slot Zero (0) of any SLC chassis such as 1746-A2, 1746-A7, 1746-A10 and 1746-A13. It is powered though the power supplied in the backplane, provided by the system power supply installed at the leftmost area of the chassis.
This SLC processor has integrated RS232 and Data Highway Plus (DH+) communication port which allows this processor to be communicated with computer-based control systems such as Human Machine Interface (HMI) or Supervisory Control and Data Acquisition (SCADA). This processor may also be used for messaging or implement pass-through communication for other Allen-Bradley Programable Logic Controller (PLC) such as PLC 5, CompactLogix and ControlLogix platforms.
This processor is built with status indicators such as Run, CPU Fault, Forced I/O, Battery Low, RS-232 and DH+ LEDs. It is also provided with a key for switching the processor’s operating mode. The Allen-Bradley 1747-L542 is an SLC 500 SLC 5/04 modular processing unit that has the capacity to handle 32K words, specifically 4K data storage and 28K words for program data. It has an absolute maximum of 4096 discrete inputs and 4096 discrete outputs, with 480 maximum local analog I/O. The 1747-L542 also has a maximum of 3 local I/O chassis, with a maximum of 30 slots in the local I/O chassis. Its I/O scan time is 0.255 milliseconds, typical program scan time is 0.9 milliseconds/Kword, and bit execution time is 0.37 milliseconds, with a program scan holdup time of 20 milliseconds to 3 seconds after a power loss.
The power scan hold-up time depends on the loading of the power supply. It also uses a Flash EPROM for its memory back-up and the 32KB RAM of the 1747-L542 processor is battery-backed. Communication ports present are an RS-232 port and a DH+ port. Status LEDs are also available, specifically for low battery, CPU fault, run, forced I/O, DH+, and RS-232. The 1747-L542’s backplane current is 1 A at 5 Volts DC and the current is 175 mA at 24 Volts DC. It operates at a temperature between 32 - 140 degrees Fahrenheit and it can be stored at a temperature between -40- and 185-degrees Fahrenheit, with an ambient relative humidity of 5 to 95%, non-condensing. This processor’s acceleration is 2.5G at 57 to 2000 Hertz, its displacement is 0.015 inches, peak-to-peak, at 5 to 57 Hertz, and its operating shock is 30G.
