diagnostics buffer - PLC Programming & Automation

S7-1500 area length error: what the diagnostics buffer is telling you

Diagram of DB120 holding an Array of 1000 Real values ending at byte 3999, with index 1000 landing on byte 4000 outside the DB, and the same three statements shown in the failing order and the correct order

An S7-1500 area length error leaves the CPU in RUN with the ERROR LED on. Read the buffer entry, find the index that runs past the array, fix the order.

PLC Scan Time and Cycle Time: Measure It, Then Cut It

by PLC

Timing chart of two 10 ms periodic task cycles showing input image update, program scan, output image update and comms overhead in sequence

Read real scan times with GSV on a ControlLogix and the cycle time view on an S7-1500, then find what is eating them before the watchdog does.