Automated Sources for Downtime

Planning for automatic downtime detection starts with auditing the available signals is the control system that can be used to determine when the line is up or down, and potentially what the root cause for downtime is. The most difficult issue is often the timing or availability of data at the instant a line goes down. While it will not be necessary to accumulate all downtime information in the control system or PLC, it may be necessary to "latch" faults, or capture "first outs" in the PLC when timing is very critical.

How to Prepare the Control System for Automatic Downtime Detection

  1. Establish the "rule" that defines whether or not the production line is up or down.

  2. Determine what fault information already exists in the control systems.

  3. Determine how the available fault information maps to specific locations or equipment.

  4. Determine the behavior of the signals making up the fault information. How fast do the fault values change? When do they change relative to the signals that determine the Production Line status? When do they change relative to the Fault information from other pieces of equipment?

  5. Establish a way to determine (or infer) the status of individual pieces of equipment along the line.

  6. Determine if fault signals "latch" for the duration of a downtime event, or change freely.

  7. Where timing is critical, supplement logic in the control system to latch faults or determine the sequencing of events to establish a "first fault".

  8. Collect all signals into the historian at the highest resolution possible.

What Can Be Automated

  • Downtime start and end times

  • Production rate capture for rate loss

  • Cause location for downtime

  • Downtime fault

  • Reasons based on fault

Examples

  • Line speed supplies downtime start and end

  • Conveyor faults determine cause location

  • Cause location determines overall fault

  • Overall fault determines default reasons

Example Types of Downtime and Waste Signals