Packaging Room Management

ProtoLink developed a DDE server to communicate with Allen-Bradley PLCs using the DF1 protocol. The server was designed specifically to support a packaging room management application utilized by a major snack food manufacturer. It performs high-speed polling for real-time production information and periodically logs collected data to an Oracle database. Examples of data logged include totals for packaging machine downtime, case counts, eye spots, and foreign matter detection events.

A handshaking scheme is implemented in the PLCs and the DDE server to ensure that counter data is not lost due to timing issues. The server supports communication with both the PLC-5 and SLC models from Allen-Bradley. This special-purpose server also provides a mechanism for adding generic PLC registers to its addressable namespace during configuration without requiring code modifications.