Allen Bradley 1747-L552

The 1747-L552 is a processor / controller with 32K user memory that is part of the SLC 500 series of PLCs.

1747-L552 Specs / Datasheet

Part Number: 1747-L552
User Memory, Max: 32K words total
(28K words for data or prog.)
(4K words for data only)
Number of I/O: 4096 in + 4096 out
absolute maximum
Local Analog I/O: 480
Max.Program Scan Time/Keyword: 0.9 ms (typ)I/O Scan Time0.225 ms (typ)
Battery: 1747-BA
Operating Shock: 30 g (modular hardware)
VibrationDisplacement: 0.015 inches peak-to-peak at 5…57 Hz
Acceleration: 2.5 g at 57…2000 Hz
Duration:1 hr per axis (x, y, z) (fixed hardware)
Environmental conditions
Operating Temperature:
0…60 °C (32…140 °F)
Nonoperating Temperature: -40…85 °C (-40…185 °F)
Relative Humidity: 5…95% noncondensing
Programming devices: RSLogix 500 Software


This Allen Bradly PLC has a few different revisions: the 1747-L552B, 1747-L552C, and the 1747-L552D. The Series C hardware for the SLC-5/05 has an all-new Ethernet daughtercard with 10/100 MB speed and improved communication performance. The Series D SLC 5/05 processors have a new main microprocessor due to component obsolescence but are functionally equivalent to Series C processors.

1747-L552 Installation

1. Required Tools and Equipment for Installation

  • Medium blade screwdriver
  • Programming equipment
  • Appropriate network interface or cable
  • 1747-UIC (requires 1747-CP3 cable), 1747-CP3, or 10/100Base-T Ethernet Network Interfaces

2. Install the 1747-L552 SLC Processor

  • Make sure system power is off; then insert the processor into slot 0 of the 1746 chassis.
  • The SLC 500 modular processors must be inserted into the left slot (slot 0). Inserting the processor in another slot won’t allow the processor to operate. In addition, remove the protective wrap after installing the processor. Failure to remove the wrap can cause the power supply to overheat.

3. Apply Power to the 1747-L552 Processor

  • Energize the chassis power supply.
  • Check the chassis power supply and processor LED indicators. The power LED indicator on the power supply should be on and the fault LED indicator on the processor should be flashing.
  • See the figure below for location of the power supply and processor LED indicators.

4. Loading Your Software

  • Refer to your specific programming software documentation.

5. Establish Communication to the 1747-L552 Processor

  • Connect a 1747-CP3 cable from channel 0 of the processor to the personal computer serial port, or connect the 1747-UIC interface converter from channel 0 of the processor to your personal computer USB port.
  • For Ethernet connection, connect channel 1 of the processor and the PC Ethernet Card to an Ethernet hub using 10/100Base-T compatible cable (EtherNet/IP address must first be set via BOOTP or an RS-232 connection).
  • Set the communication parameters of the software to match the default parameters of the processor.
  • Channel 0
  • DF1 Full-duplex: • no handshaking
  • 19.2 Kbaud
  • CRC Error Check
  • duplicate detect on no parity

6. Replace the Battery

Your Allen-Bradley 1747-L552 processor provides back-up power for RAM through a replaceable lithium battery. This battery provides back-up for approximately 2 years. The BATT LED indicator on the front of the processor alerts you when the battery voltage has fallen below a threshold level.

To replace the lithium battery follow these steps;

  • Remove power from the 1747-L552 power supply.
  • Remove the processor from the chassis by pressing the retainer clips at both the top and bottom of the module and slide it out.
  • Unplug the battery connector.
  • Remove the battery from the retaining clips.
  • Insert a new battery into the battery retaining clips.
  • Plug the battery connector into the socket as shown below.
  • Re-insert the module into the SLC 500 chassis.
  • Restore power to the SLC 500 power supply
  • Close the processor door.

7. Troubleshooting Your SLC 1747-L552 Processor

Between the time you apply power to 1747-L552 processor and the communication are established via a connected programming device, the only form of communication between you and the processor is through the status indicator display.

When power is applied, all of the status indicators flash on and then off while the processor conducts hardware tests. This is part of the normal power-up sequence.

Following the self-test by the processor, all the status indicators again flash on momentarily. If a user program is in a running state, the RUN status indicator will be on. If a fault exists within the processor, the FLT status indicator is on.

Follow these steps to receive the maximum benefit of this troubleshooting section.

  • Using the tables on the following pages, match your processor and power supply status indicators with the status indicators in the first column.
  • Once the status indicators are matched to the appropriate table, move across the table identifying error description and probable causes.
  • Then follow the recommended action steps for each probable cause until the cause is identified.
  • If recommended actions do not identify the trouble cause, contact a local Rockwell Automation distributor or your machine builder.

Clearing 1747-L552 Processor Faults Using the Keyswitch:
Toggle the keyswitch from RUN to PROG and then back to RUN; this will clear some faults. If the keyswitch is left in the RUN position, the processor mode cannot be changed from a programmer/operator interface device. If you return the keyswitch to the REM position, you can then use a programmer/operator interface device to change the processor mode.

8. AB 1747-L552 Communication Options

These are the communication options for the 1747L552 processors are as follows:
• DH485
• RS-232 protocols (DF1 Full-duplex, DF1 Half-duplex master/slave, DF1
Radio Modem, DH-485, or ASCII)
• Data Highway Plus (A ControlLogix Gateway is required for the SLC 5/03
and SLC 5/05 processors.)
• Ethernet TCP/IP (A 1761-NET-ENI interface module is required for the SLC
5/03 and SLC 5/04 processors)
• ControlNet (via a 1747-KFC15 module)
• DeviceNet (via a 1761-NET-DNI interface module)

9. 1747-L552 Memory Backup

The part number for the Flash EPROM used with the 1747-L552 is the 1747-M13 (OS501 Series C or later).