PLC Machine Data Logging System

A shop-floor PC reads an existing PLC and stores each cycle so production staff can look back at what the machine did.

Problem: The machine already runs from a PLC, but cycle results, process values, and alarms stay in the controller. After a shift, there is no practical way to review what happened.
Solution: Edge software on a PC beside the machine reads the agreed registers and writes a record for each cycle. The PLC sequence is left in place. Logging is added on top of it.
Hardware: The installed Mitsubishi, Delta, or Omron PLC, plus an industrial or panel PC on the plant network. No controller brand is swapped in for the sake of the logger.
Software: Custom software in C# / .NET or Python, with SQLite or SQL Server-style storage depending on what the plant already uses. A Windows screen shows the latest cycles.
Communication protocol: Modbus TCP, Modbus RTU, Ethernet, or serial — whichever port and protocol that PLC already exposes.
Data collected: Timestamps, cycle identity, process parameters agreed with the process owner, alarm and event bits, and machine status. The list is taken from the PLC map, not from a generic template.
Result: Each stored cycle can be opened later from a PC on the plant network. Customer names and numerical before/after claims are not published on this page.

This logging path is part of Industrial IoT and industrial data acquisition. Changes to the controller program itself are PLC programming.