1747-L532 — SLC 5/03 Modular Processor, 8K Memory, DH-485/RS-232

The 1747-L532 is an SLC 5/03 series programmable processor module for the SLC 500 modular chassis system. It provides 8 KB of user program memory, two communication ports (DH-485 and RS-232), and the full SLC 5/03 instruction set including PID, ASCII messaging, and math instructions. The processor installs in Slot 1 of a 1746-series chassis and draws on the chassis backplane to communicate with I/O modules installed in adjacent slots.

The SLC 5/03 sits in the middle of the SLC 500 processor family — faster and more capable than the 5/01 and 5/02, but without the Ethernet connectivity of the 5/05. Its DH-485 port makes it compatible with legacy data highway networks, and its RS-232 port handles direct programming connections and communication with HMIs, drives, and instruments over DF1 or ASCII protocols. For facilities running SLC 500 systems that were installed in the 1990s and 2000s, the 1747-L532 remains the replacement processor for 5/03-based panels.

Specifications

Parameter	Value
Part Number	1747-L532
Processor Type	SLC 5/03
User Program Memory	8 KB
Data Table Memory	5.5 KB (shared with program memory)
Scan Time (typical)	0.9 ms per K of logic (for typical ladder)
Communication Port 0	DH-485 (multi-drop network, 19.2 kbps)
Communication Port 1	RS-232 (DF1 full/half-duplex, ASCII, DH-485)
Local I/O Slots	Up to 30 (across multiple chassis on DH-485)
Max I/O (local + expanded)	4096 I/O addresses
Instruction Set	Standard ladder + PID, ASCII, math, sequencer
Battery	Lithium coin cell (backs up program and data in power loss)
Chassis Compatibility	Any 1746 modular chassis (4 to 13 slots)
Operating Temperature	0°C to 60°C
Standards	UL 508, CE

Maintaining an SLC 5/03 Installation

For facilities committed to keeping SLC 500 systems running, several maintenance practices reduce unplanned downtime risk:

Battery monitoring: the lithium battery backing the processor's program and data memory has a finite life — typically 3–7 years depending on temperature and backup frequency. RSLogix 500 shows battery status in the processor's status file (S2:12, S2:13). Replace the battery on a calendar schedule, not when the low-battery warning appears — the warning provides limited advance notice. Keep a spare battery in the spares kit.
Program backup: maintain a current backup of the RSLogix 500 program file (.RSS) in at least two locations. A processor that fails without an available backup requires the program to be reconstructed from scratch or recovered by a specialist. Backups should be updated any time the program is modified in the field.
Port configuration documentation: document Port 0 and Port 1 configuration settings (baud rate, station address, protocol) in writing and store this with the panel documentation. When a replacement processor is installed, these settings must be re-entered manually — they're not restored from a program backup automatically.
Spare module: for critical production equipment, keeping a spare 1747-L532 on the shelf avoids extended lead time sourcing if the installed processor fails. Ensure the spare has been tested and has current firmware installed.

When replacing a 1747-L532, the new processor requires firmware to be loaded before it will accept the program download. Verify the replacement processor's firmware revision matches the existing system's requirements. Firmware for SLC 500 processors is managed through RSLogix 500 — a firmware mismatch between the processor and the program file can prevent proper program execution after replacement.

FAQ

Q: What programming software is used for the 1747-L532?

RSLogix 500, which runs on Windows. RSLogix 500 supports all SLC 500 processor variants from 5/01 through 5/05. The same software is used for online programming, monitoring, and fault diagnostics across the entire SLC 500 family.

Q: Can the DH-485 port communicate with devices outside the SLC 500 family?

DH-485 is a proprietary network protocol — direct interoperability with non-SLC equipment is limited. 1761-NET-AIC converter modules can bridge DH-485 to RS-232 for devices that understand DF1, and some HMIs and SCADA systems include DH-485 drivers. For modern integration, the RS-232 port using DF1 or Modbus RTU is more widely compatible with third-party equipment.

Q: Can the SLC 5/03 processor handle motion control?

Not natively. The SLC 5/03 has no built-in motion control instructions. Basic step control using output timing sequences is possible in ladder, but closed-loop servo motion requires a motion controller platform. For systems that need servo motion, the SLC 500 is not the appropriate platform.

Q: Is the 1747-L532 compatible with the 1747-L531 (4 KB) or 1747-L533 (16 KB) programs?

The 5/03 instruction set is the same across the 31, 32, and 33 variants — only memory size differs. A program from a 1747-L531 (4 KB) will run on a 1747-L532 (8 KB) without modification, as long as it fits within memory. A program from a 1747-L533 (16 KB) will only load if it fits within the 8 KB available on the L532.

Q: What is the DH-485 node limit, and does this processor count against it?

DH-485 supports up to 32 nodes (addresses 0–31) on one network. The 1747-L532 occupies one address on the DH-485 network. Additional nodes — other SLC processors, HMIs, operator terminals, and network interfaces — consume the remaining addresses. For networks approaching the 32-node limit, review all connected devices and their address assignments carefully before adding new nodes.

1747-L532 New Factory Sealed 1747L532 SER E SLC 500 PLC Processor Unit Module