Structured Text - PLC Programming & Automation

The 5 PLC Programming Languages and When to Use Each

September 12, 2026February 3, 2024 by PLC

Ladder rung with Start_PB XIC, seal-in branch on Conv_Run, Stop_PB XIO and Guard_OK XIC driving the Conv_Run OTE coil

Ladder, FBD, Structured Text, SFC and IL compared on real hardware: what Studio 5000 v33 and TIA Portal V18 support, and which one to pick per job.

Sequential Function Chart PLC Programming, Step by Step

September 12, 2026January 20, 2024 by PLC

Timing chart of SFC step activity in a batch sequence, showing Step_Fill, Step_Mix, Step_Drain and the mixer output over sixty seconds

Build a working SFC in Studio 5000: steps, transitions, action qualifiers, the SFC Execution settings that decide what happens on a restart, and S7-GRAPH.

Fuzzy Logic PLC Control: Rule Tables, Inference in ST and a Dryer Example

September 13, 2026January 20, 2024 by PLC

Ladder rung with Dryer_Run examined on, Burner_Fault examined off and HMI_Fuzzy_Sel examined on in series, driving the Fuzzy_Active output coil

Where fuzzy control beats PID, how to hand-code memberships, a 3×3 rule table and weighted-average defuzzification in Logix ST, with a dryer example.

Timer and Counter Instructions

September 13, 2026June 25, 2020 by Admin

Reference for Logix timer and counter instructions TON, TOF, RTO, CTU, CTD, and their function block equivalents, with the 1 ms timer base explained.