scada - PLC Programming & Automation

Good Quality, Stale Value: Diagnosing an OPC Link That Is Lying to You

Five boxes in a row from the controller through the driver, the server cache and the subscription to the client, with four numbered red break points marked underneath

Seal_Temp has read 182.4 °C since about 04:00, the quality field next to it says Good, and the trend behind it is a flat line eleven hours long. The bagger has run four product changes in that time and the seal jaws are visibly hot. Nothing on the SCADA is in alarm, nothing in the … Read more

Kepware Channels, Devices and Tags: the Structure to Get Right Before the First Tag

by PLC

Five boxes in a row showing one value walking from the controller through the channel, the device, the tag group and the server tag, with four numbered red points below marking where the chain breaks

A SCADA client stores one string for every value it reads, and on the line I am about to describe that string is CLX_Line1.Bagger.Infeed.Belt1_Run. Four names, each chosen by a different person on a different day, and 684 more strings on that one device built the same way. Rename the tag group on a Friday … Read more

PLC Communication Protocols for SCADA: What to Pick

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Timing chart comparing polled Modbus TCP requests and responses at 25 ms against cyclic EtherNet/IP I/O packets at a 10 ms RPI

Modbus TCP, EtherNet/IP, PROFINET, OPC UA and MQTT compared by how they move data, with ports, poll rates and the mistakes that cost SCADA update time.

Generator Start Permissives, Sync Handover and Load Shed

by PLC

Ladder rung for a generator start permissive: start push button sealed in, lube oil pressure healthy, generator breaker open, lockout relay reset, driving the start sequence coil

Where the PLC stops and the relay starts, a generator start permissive rung, the synchronising handshake, load shed stages and switchgear interlocks.

SCADA PLC Integration: Connect Ignition to ControlLogix

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Timing chart of a one second SCADA tag group: the group tick, the CIP read request, the controller reply about 60 ms later, and the historian insert

Pick the protocol, prepare the controller tags, add the device in Ignition, set a sane tag group, then prove the link survives a network drop.

PLC Cybersecurity: Hardening a Logix Cell Step by Step

by PLC

Timing chart of a controller restart: run mode drops while the download happens, then the first scan bit pulses, the restart timestamp is written and the unplanned download alarm latches on the SCADA

Zones and conduits, the controller key switch, FactoryTalk Security, firewall rules for 44818 and 502, and a backup you have actually restored.

OPC UA PLC Integration: From PLC Tag to SCADA Client

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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.

What is SCADA?

by PLC

What is SCADA? Supervisory Control And Information Purchase or SCADA is a system utilized to keep track of and regulate a plant create a main location. This is not regularly made use of because of the control override possibility. SCADA itself changes the control set factors quite often. It is widely used in water therapy … Read more

Factorytalk View Site Edition

by PLC

Available FactoryTalk View SE application types are: Network Distributed Network Station Local Station. FactoryTalk View Studio is the development environment for all FactoryTalk View applications. This type of application allows a client/server architecture (multiple clients and server computers), allows you to have multiple HMI servers (local/remote), multiple clients (local/remote), and enables your The HMI server … Read more