Articles - PLC Programming & Automation

PLC PID Control: Set Up and Tune a Loop in Studio 5000

Timing chart of a loop startup: setpoint step, control output saturated at 100 percent, deviation alarm active, then the process variable settling inside a 1 degC band

Scale the analog signals, pick PID or PIDE, put the loop in a periodic task, then tune from a bump test. Siemens PID_Compact covered as well.

OPC UA PLC Integration: From PLC Tag to SCADA Client

by PLC

Timing chart of an OPC UA subscription showing 250 ms sampling pulses, a PLC tag value change, and notifications leaving at the 1 second publishing interval

Connect a PLC to SCADA with OPC UA: KEPServerEX channels, the S7-1500 built-in server, certificate trust, subscription rates and why OPC DA kept breaking.

PLC Water Treatment: Levels, Lead/Lag Pumps and Dosing

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Timing chart of lead and lag pump alternation: the lead call starts pump 1, the lag call brings in pump 2 at high level, and on the next cycle pump 2 takes the lead

Wet well level control, pump alternation that shares the wear, chlorine dosing with long dead time, and remote sites over cellular Modbus that go quiet.

PLC vs DCS Integration: Getting a Skid onto the DCS

by PLC

Timing chart of a DCS to PLC heartbeat: the DCS counter steps every second, the PLC echoes it, and the Comms OK bit drops three seconds after the counter freezes

How a packaged skid PLC gets tied into DeltaV, Experion or PCS 7: link protocol, Modbus register map, heartbeat, engineering units and alarm ownership.

HMI PLC Setup: Build Your First PanelView Plus Screen

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Timing chart showing a finger press on the HMI, the tag write, the PLC Start_PB bit and the resulting Motor_Run coil, with about 60 ms of delay between each

From a blank FactoryTalk View ME application to a running PanelView Plus screen: shortcuts, tag syntax, a momentary push button and the MER transfer.

EtherNet/IP PLC Communication: Setup, RPI and Faults

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Timing chart of EtherNet/IP implicit I/O at 10 ms RPI showing producer and consumer packets against a 25 ms periodic task scan

Set up EtherNet/IP between a Logix controller, remote I/O and a drive: RPI, unicast vs multicast, MSG paths, and the fault codes you will really see.

PLC MES Integration: Tags, Handshakes and Work Orders

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Timing chart of an MES to PLC work order handshake showing Request from the MES, Ack from the PLC, Done when the order is latched, and both bits clearing after Request drops

What MES really needs from the controller: OEE counters, downtime reason codes, a work order UDT, a request and acknowledge handshake, an OPC UA bridge.

EtherCAT PLC Systems: Cycle Time and Distributed Clocks

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Timing chart of a 1 ms EtherCAT cycle showing the task window, the frame on the wire, and the SYNC0 pulse that applies outputs on every slave at the same instant

Set up an EtherCAT bus in TwinCAT 3: ESI files, scanning the line, picking a cycle time, distributed clocks and the CRC counters that find a bad cable.