1747-PIC | Allen-Bradley SLC 500 RS-232 to DH-485 Interface Converter for SLC 5/01–5/03 Processors

The 1747-PIC is a communication interface converter that connects RS-232 serial devices, like a PC, to DH-485 networks used in Allen-Bradley SLC 500 systems. It acts as a translator between these two protocols, enabling reliable data exchange between older SLC 5/01, 5/02, or 5/03 processors and computers. This allows users to program, monitor, and troubleshoot PLCs using serial-based communication. The converter is especially helpful in legacy systems where DH-485 remains the standard. It’s commonly used with RSLogix 500 and RSLinx software. Its role is vital in maintaining older industrial control networks.

The 1747-PIC uses a DB25 (25-pin D-sub) connector on the PC side. This was common in older computer systems that had native serial ports. It connects to the PLC’s DH-485 port through a dedicated cable, such as the 1747-C10. The connector provides a secure link and ensures proper signal flow. However, due to its age, it’s not compatible with modern laptops without additional adapters. A true RS-232 port is necessary for full functionality. Miswiring the connector can result in communication errors.

No, the 1747-PIC does not support Ethernet or modern network protocols. It is limited to RS-232 serial input and DH-485 serial output. It cannot be used to connect to devices that require Ethernet/IP or TCP/IP communication. For Ethernet-compatible controllers like SLC 5/05, separate Ethernet modules or built-in ports must be used. If Ethernet is required in a DH-485 environment, network bridges or newer communication modules are needed. The 1747-PIC’s functionality is purely for legacy serial communication.

While some users have reported limited success, the 1747-PIC is generally not compatible with USB-to-serial adapters. The timing requirements of DH-485 communication are very strict and often not met by USB interfaces. This can cause failed connections, timeouts, or unstable communication. Rockwell explicitly states that USB adapters are not supported for this module. For systems without a native COM port, the 1747-UIC is the official USB replacement. Using the correct interface ensures consistent, reliable communication with SLC processors.

No, the 1747-PIC has been officially discontinued by Rockwell Automation. While it was once widely used, advancements in communication technology and the rise of USB and Ethernet protocols have rendered it obsolete. Although not manufactured anymore, the module can still be found through surplus distributors and used equipment vendors. It is still supported in documentation for legacy SLC 500 systems. For new installations, Rockwell recommends using the 1747-UIC USB converter instead. Migration is encouraged where possible to ensure long-term support.