Allen Bradley 1747-L542 Series B

Allen Bradley 1747-L542 Series B Processor Module

The Allen-Bradley 1747-L542 is a mid-range SLC 5/04 processor for the SLC 500 modular hardware platform, offering 32KB of user memory while supporting up to 4,096 discrete inputs and 4,096 discrete outputs. It installs in slot 0 of any 1746 modular chassis such as the 1746-A4, 1746-A7, 1746-A10, or 1746-A13, and is powered via the chassis backplane.

Total user memory is 32K words — 28K words available for program or data use and 4K words reserved for data only. Local analog I/O capacity is 480 points maximum, with support for up to 3 local I/O chassis and a maximum of 30 I/O module slots. Program scan time is 0.9ms per Kword (typical) and I/O scan time is 0.225ms (typical). Memory is battery-backed RAM with Flash EPROM backup to protect the user program against battery failure.

The processor features integrated RS-232 and Data Highway Plus (DH+) communication ports. The RS-232 port can also be configured for a DH-485 network, providing flexibility in network topology. These ports enable connectivity to HMI, SCADA, and other Allen-Bradley platforms including PLC-5, CompactLogix, and ControlLogix via pass-through communication and messaging.

Front-panel status LEDs indicate Run, CPU Fault, Forced I/O, Battery Low, RS-232, and DH+ status. Backplane current draw is 1A at 5VDC and 175mA at 24VDC. The processor operates between 0–60°C (32–140°F) at 5–95% non-condensing humidity, with a 30G operating shock rating and 2.5G vibration tolerance at 57–2000Hz.

Key Specifications:

• Brand Allen Bradley
• Catalog Number: 1747-L542 Series B
• Processor Type: SLC 5/04
• User Memory: 32K words (28K program/data + 4K data only)
• Max Discrete I/O: 4,096 inputs / 4,096 outputs
• Max Analog I/O: 480 points
• Max Local Chassis: 3 / Max Slots: 30
• Program Scan Time: 0.9ms/Kword (typical)
• I/O Scan Time: 0.225ms (typical)
• Communication: DH+ and RS-232 (configurable for DH-485)
• Backup Memory: Flash EPROM + battery-backed RAM
• Backplane Current: 1A @ 5VDC / 175mA @ 24VDC
• Platform: SLC 500 (1746 Chassis, Slot 0)

Applications

Allen Bradley SLC 500 SLC 5/04 CPU Processor, 32K User Memory (28K Program/Data + 4K Data), 4096 Max Discrete I/O, 480 Max Analog I/O, DH+ & RS-232 Communication Ports (RS-232 Configurable for DH-485), Flash EPROM + Battery-Backed RAM, 0.9ms/Kword Scan Time, 3 Chassis / 30 Slots Max, Backplane Current 1A @ 5VDC / 175mA @ 24VDC, Series B

Buying Notes

Verify catalog reference, electrical ratings, connector or mounting requirements, and compatibility with your control system before purchase.