SCADA Articles
Longer-form technical writing, published as it is finished and revised as field experience corrects it. Every entry carries its published and updated dates.
119 entries
Alarms in the Controller
Generating alarm conditions in the controller rather than in the graphics: why the PLC should own the alarm state, a standard alarm block with setpoints, deadband, and delays, equipment alarms, and packing alarm bits for SCADA.
9 min readUpdated Sep 5, 2026
DNP3
The protocol built for utility telemetry: master and outstation, static and event data classes, unsolicited reporting, time-stamped events, and why it suits slow links that Modbus does not.
8 min readUpdated Sep 5, 2026
OPC UA
What OPC UA is for, how its information model, security, and transports differ from OPC Classic, where it belongs in a plant, and what to check before relying on it.
8 min readUpdated Sep 5, 2026
ISA-101: Human Machine Interfaces
What the ISA-101 standard for human machine interfaces covers, its lifecycle from philosophy to maintenance, the display hierarchy, and what adopting it changes on a project.
8 min readUpdated Sep 5, 2026
SCADA Architecture
The parts of a SCADA system and how data moves between them: I/O servers, the tag database, clients, the historian, the alarm server, and the topologies from a single panel PC to a redundant, distributed plant.
9 min readUpdated Sep 5, 2026
Historians
What a process historian does that a database does not, how data gets into it, how compression and retrieval work, how to size and keep it, and the settings that quietly throw data away.
8 min readUpdated Sep 5, 2026
SCADA Redundancy
What redundant SCADA servers protect against and what they do not, how failover works for tags, alarms, history, and clients, the network and controller layers beneath it, and why an untested failover is not redundancy.
8 min readUpdated Sep 5, 2026
The Alarm Philosophy
The document that decides what is allowed to be an alarm: the definition, the criteria, the priorities and their meaning, the performance targets, the handling rules, and who owns it. Under ISA-18.2 it comes first.
9 min readUpdated Sep 5, 2026
Alarm Priority
How to assign alarm priorities that operators trust: a consequence-and-time matrix, three or four levels, the target distribution from ISA-18.2 and EEMUA 191, and the mistakes that make every alarm high.
9 min readUpdated Sep 5, 2026
Alarm Rationalization
The meeting where every alarm earns its place: who attends, what is decided for each alarm, how to document it in a master alarm database, and how to run it at a utility that cannot spare a week.
10 min readUpdated Sep 5, 2026
Alarm Floods
What an alarm flood is, why it happens at exactly the wrong moment, the ISA-18.2 rate targets, and the design measures that keep a power failure or a communication loss from burying the one alarm that matters.
10 min readUpdated Sep 5, 2026
Alarm Notification and Callout
Getting the alarm to the person on call when no one is watching the screen: notification paths, escalation, acknowledgment from the field, which alarms qualify, and the failure modes that leave a station in high level with nobody paged.
10 min readUpdated Sep 5, 2026
HMI Faceplates
The pop-up that controls one device: what a pump, valve, or loop faceplate must show, the mode and command layout, interlock and permissive display, security by role, and building faceplates from a standard object so every device behaves the same.
10 min readUpdated Sep 5, 2026
Trends on the HMI
Trend displays that answer questions: embedded sparklines on process displays, pre-configured trend groups, the axes and time spans that make a trend readable, and the difference between a trend for operating and a trend for investigating.
9 min readUpdated Sep 5, 2026
Alarm Indication on the HMI
How an alarm looks and sounds on the operator screen: the ISA-101 and ISA-18.2 rules for color, shape, and blink, the alarm banner and summary, acknowledgment behavior, navigation to the alarm, and indication that survives colorblindness and a noisy control room.
10 min readUpdated Sep 5, 2026
HMI Navigation
How operators move through the displays: the display hierarchy from overview to detail, a fixed navigation bar with area alarm indication, one-click paths from an alarm to the device, the rules that keep any display within two clicks, and what to leave out.
9 min readUpdated Sep 5, 2026
Historian Architecture
How process history is collected, stored, and served: the collector, the archive, and the client layers, where the historian sits relative to SCADA and the DMZ, single-server and tiered designs for a utility, the store-and-forward buffer that survives outages, and the sizing that decides how many years fit on a disk.
9 min readUpdated Sep 5, 2026
Historian Data Collection
Deciding what the historian stores and how often: polled versus exception collection, the deadband per tag, rates for control loops, levels, totals, and compliance values, timestamps at the source, quality codes, calculated tags, and the tag list review that keeps a historian from filling with noise and missing what matters.
9 min readUpdated Sep 5, 2026
Historian Compression
How historians store years of data on a disk: exception deadbands at the collector, swinging door compression at the archive, what each discards and what it keeps, the settings that turn a trend into a staircase, lossless alternatives, and how to check that the compressed data still tells the truth.
8 min readUpdated Sep 5, 2026
Reporting from the Historian
Turning history into the reports a utility must produce: the monthly operating report, compliance reports for the regulator, daily operator summaries, pump run and energy reports, the calculations behind daily minimums, maximums, and totals, handling bad quality and gaps, and building reports once so they run every month without an engineer.
9 min readUpdated Sep 5, 2026
SCADA Servers
What the servers in a SCADA system do and what a utility should expect of them: the I/O, alarm, historian, and client roles, physical versus virtual, redundancy, sizing, placement, backup, patching, licensing, and monitoring.
10 min readUpdated Sep 5, 2026
SCADA Clients
The workstations, browsers, and mobile devices operators use to see and control the system: thick, thin, web, and mobile clients, roles and permissions, where control is allowed from, workstation design, session policy, licensing, and failover behavior.
9 min readUpdated Sep 5, 2026
Alarm Servers
The part of SCADA that turns a condition into an alarm and manages its life: where detection happens, the alarm state machine, priority, deadband and delays, acknowledgment across clients, the journal, notification, redundancy, timestamps, and flood behavior.
10 min readUpdated Sep 5, 2026
SCADA Communications
How SCADA servers talk to controllers and the field: polling and report by exception, the protocols and what each is for, media from plant Ethernet to radio and cellular, poll rate arithmetic, timeouts and quality, time sync, store and forward, and security.
11 min readUpdated Sep 5, 2026
Color in HMI Design
How color is used on a high performance HMI: a gray palette for normal operation so that color means something, alarm colors reserved by priority, equipment state by fill and text rather than red and green, color-blind safe choices, and the palette table.
9 min readUpdated Sep 5, 2026
Situational Awareness
Designing displays so an operator knows what is happening, what it means, and what comes next: the three levels of awareness, the display hierarchy, analog indicators with normal ranges, embedded trends, time-to-limit predictions, and a test for any display.
10 min readUpdated Sep 5, 2026
Alarm Shelving
The operator tool for temporarily silencing a nuisance alarm: what shelving is and is not, the rules a philosophy sets, who may shelve what and for how long, automatic unshelving, the shelved list, the record, and how to implement it on any platform.
8 min readUpdated Sep 5, 2026
Alarm Suppression
Suppressing alarms by design: state-based logic that removes alarms that mean nothing in the current state, parent-child logic that stops a flood at its source, out-of-service suppression for maintenance, the rules that keep it safe, and how to test it.
9 min readUpdated Sep 5, 2026
Trending
Using historian trends to understand a process and diagnose a problem: pens that belong together, scaling and time ranges, raw versus averaged data and what compression hides, overlays and cursors, event markers, and the patterns that point at each cause.
9 min readUpdated Sep 5, 2026
Frozen Values
Why a SCADA value stops changing while looking normal: the five layers where it can freeze, from a transmitter holding its output to a client that lost its server, how to find the layer by comparing each, and the heartbeat that makes a freeze announce itself.
9 min readUpdated Sep 5, 2026
Lost Communications
What should happen when SCADA loses a device, a site, or everything, how the pattern tells which, the diagnostic order from the server outward through network, firewall, medium, and site, and the design that makes a lost link an alarm rather than an incident.
9 min readUpdated Sep 5, 2026
Bad Quality
What a quality flag means and where it comes from: good, uncertain, and bad with substatus codes, how quality propagates from device through driver, tag, display, alarm, and historian, the causes by layer, and the rule that a bad value is never a number.
9 min readUpdated Sep 5, 2026
Server Failure
How SCADA servers fail and what to do when one does: failure modes from a full disk to a dead hypervisor host, what the plant experiences with and without redundancy, the recovery sequence from restore to alarm verification, and the monitoring that warns.
9 min readUpdated Sep 5, 2026
Client Problems
Diagnosing the operator station rather than the system: a client that will not connect, shows nothing, runs slowly, freezes, or stays silent on an alarm, with the causes, the order of checks, and the standard build and spare that make the fix a swap.
8 min readUpdated Sep 5, 2026
Historian Problems
How a historian goes wrong and how to find each fault: gaps, wrong values, detail never stored, disks that fill, slow queries, backfill that never arrives, and unreadable archives, with the collector, queue, configuration, and storage checks that locate it.
9 min readUpdated Sep 5, 2026
Alarm Problems
How an alarm system fails: alarms that never raise, raise unheard, stick, chatter, or flood, acknowledgments that do not propagate, and notifications that never arrive, with the causes by layer and the end-to-end test that proves the whole chain.
9 min readUpdated Sep 5, 2026
Time Synchronization
Why every clock in a control system must agree and what happens when they do not: out-of-order events, historian gaps at daylight saving, authentication failures, wrong totals. The time source and hierarchy, how each device is synchronized, and the checks.
9 min readUpdated Sep 5, 2026
Long-Term Storage
Keeping historian data for years: a retention policy by data class that follows the record rules, tiered storage from online to offline copies, downsampling, archive management, exports that outlive the historian, and the annual proof that old data reads.
9 min readUpdated Sep 5, 2026
SQL Integration
Connecting SCADA and historian data to relational databases: why a utility does it, the methods, a schema that handles time series, the query patterns for totals and reports, the mistakes that flood a database or stall a server, and security.
10 min readUpdated Sep 5, 2026
VTScada
Field notes on VTScada, the Trihedral platform widely used by municipal water utilities: the all-in-one design with historian, alarm notification, and thin clients built in, server redundancy, application versioning, telemetry drivers, and licensing by tags.
8 min readUpdated Sep 5, 2026
Ignition
Field notes on Ignition from Inductive Automation: gateway and modules, unlimited licensing per server, Perspective and Vision clients, the SQL-based historian, Python scripting, redundancy, Edge for small sites, and what to decide before building on it.
8 min readUpdated Sep 5, 2026
GE iFIX
Field notes on iFIX, the long-established SCADA from the Intellution and GE lineage now sold by GE Vernova: SCADA nodes and the process database, I/O drivers, view and web clients, the Proficy Historian, enhanced failover, scripting, and licensing by points.
8 min readUpdated Sep 5, 2026
AVEVA
Field notes on the AVEVA operations software family, formerly Wonderware: InTouch HMI, System Platform and its object model, the Historian, Plant SCADA from the Citect lineage, and AVEVA Edge. Which product does what, and what to check on site.
8 min readUpdated Sep 5, 2026
Rockwell FactoryTalk
Field notes on the Rockwell Automation FactoryTalk family: View Site Edition and Machine Edition, the directory, Linx with direct controller tag access, device-based Alarms and Events, the PI-based Historian, ViewPoint and Optix, redundancy, and site checks.
8 min readUpdated Sep 5, 2026
Schneider SCADA
Field notes on Schneider Electric SCADA for water: EcoStruxure Geo SCADA Expert, formerly ClearSCADA, the telemetry platform built around DNP3 events, an object database, and hot standby servers, with SCADAPack RTUs, and how it relates to the AVEVA products.
8 min readUpdated Sep 5, 2026
Other Platforms
The SCADA and HMI products a water utility may meet beyond the common ones: Siemens WinCC, distributed control systems, independent SCADA products, hosted lift station monitoring, and open-source tools, and the questions that decide whether one belongs.
8 min readUpdated Sep 5, 2026
Tank Level Control
How a storage tank is filled and drawn on level setpoints, how the setpoints are chosen to keep the water turning over, and what the station does when the tank stops talking.
8 min readUpdated Sep 5, 2026
Elevated Tank Control
The tank on legs that sets the zone pressure: how level equals pressure, the operating band, the altitude valve and its telemetry, turnover for water quality, filling by pumps far away, freeze protection, and what the level signal does when the tank is holding the system together.
10 min readUpdated Sep 5, 2026
Raw Water
Controlling the front of a surface water plant: intake and screens, low-lift pumping, the raw water flow that paces the whole plant, the online quality instruments that warn of a changing source, and the alarms and ramp limits that keep the train stable.
9 min readUpdated Sep 5, 2026
Ground Storage Tanks
Controls for ground storage tanks: level measurement and its datum, filling from wells and treatment by pump control or altitude valve, and the telemetry that ties the tank to the system.
8 min readUpdated Sep 5, 2026
Lift Station SCADA
Getting a remote station onto the SCADA system and keeping it there: which signals to bring back and which controls to allow, the telemetry path from licensed radio to cellular to fiber, and the maintenance that keeps the link up.
9 min readUpdated Sep 5, 2026
Effluent
Effluent from the controls side: the flow measurement the permit is built on, the composite samplers it paces, the parameters measured online, flow, pH, dissolved oxygen, residual, turbidity, and the data integrity that makes the record defensible.
8 min readUpdated Sep 5, 2026
Vendor Remote Access
Integrators and equipment vendors need to get in. How to let them without leaving a permanent door open: utility-controlled sessions, named accounts, MFA, a jump host, session recording, and what to do about the modem you did not know was there.
11 min readUpdated Sep 5, 2026
Industrial DMZ Design
The buffer zone between the business network and the control system: what goes in it, the no-direct-path rule, push-not-pull data flows, the firewall pair, and the services a utility actually needs to place there.
10 min readUpdated Sep 5, 2026
Jump Hosts
The one machine every remote session must pass through: what a jump host is, how it is hardened, what it may reach, session recording, the tools it carries, and why a vendor laptop never gets past it.
9 min readUpdated Sep 5, 2026
What to Back Up in a Control System
What a utility must be able to restore after a failure or attack: controller programs and firmware, SCADA and historian, HMI panels, drive and instrument parameters, network configurations, licenses, installers, and documentation, and how often each changes.
10 min readUpdated Sep 5, 2026
Server Hardening
Reducing what an attacker can do with a SCADA server: a baseline from the vendor guide and a benchmark, unused services removed, the host firewall on, application allowlisting, controlled media, separate administrator accounts, and logs sent off the box.
10 min readUpdated Sep 5, 2026
User Accounts and Roles
Who can do what on the SCADA and how it is enforced: roles from view-only to administrator and their permission matrix, individual accounts including the operator console, service and vendor accounts, same-day offboarding, and the quarterly review.
9 min readUpdated Sep 5, 2026
Patch Management
Applying updates to SCADA servers and clients without breaking the plant: vendor qualification, a monthly cycle with a test system, priority from the exposed edge inward, backups and rollback, emergency patches, and handling software that cannot be patched.
9 min readUpdated Sep 5, 2026
Historian Security
The historian is the most connected server in a control system and the most exposed: giving the office, reports, and the cloud the data they need without a path to the plant, with a collector in the control zone, a replica in the DMZ, and one-way flow.
9 min readUpdated Sep 5, 2026
Third-Party Software
Everything on a control system machine that is not the SCADA: drivers, databases, runtimes, reporting tools, agents, remote support utilities. Why each is an attack surface, the inventory and approved list, rules for installs, and removing what is unused.
8 min readUpdated Sep 5, 2026
Shared Account Problems
Why the shared operator login, the vendor account everyone knows, and the single PLC password are the weakest point in most utilities: no accountability, no offboarding, no detection. Containing what cannot be avoided and migrating the rest.
8 min readUpdated Sep 5, 2026
Password Policy for OT
A password policy that fits a control system rather than an office: length over complexity, rotation on events, screening against breached lists, multi-factor authentication, no lockouts that take control from an operator, and unique vaulted device passwords.
8 min readUpdated Sep 5, 2026
Credential Storage
Where the passwords and keys of a control system are kept: a vault with individual access and a log, break-glass copies in a safe, platform credential stores for service accounts, and the places they must not be, from spreadsheets to project files.
8 min readUpdated Sep 5, 2026
SCADA Backups
What a SCADA backup must contain to bring a system back: the project export, an image of each server, the databases, historian archives, licenses, certificates, scripts, and network device configurations, with frequency, retention, and the restore procedure.
9 min readUpdated Sep 5, 2026
Backup Testing
Why backups that have never been restored fail when needed, and how to find out: spot restores, full restores of a server to an isolated machine, controller program restores to a spare, archive reads, timing each one, and the findings and record that follow.
8 min readUpdated Sep 5, 2026
Offline Copies
The backup copy that survives ransomware: why anything reachable over the network will be encrypted too, what offline and immutable mean, options from rotated drives to immutable storage, what goes in the offline set, and the restore test that uses it.
8 min readUpdated Sep 5, 2026
Configuration Baselines
A known-good record of how every part of the control system is configured, captured at acceptance and kept current through change management: what to baseline, how to capture and store it, how to compare on a schedule, and what an unexplained difference means.
8 min readUpdated Sep 5, 2026
Program Change Detection
Knowing when a controller program changed and whether it was supposed to: change counters and signatures the SCADA can alarm on, scheduled compares, audit logs, mode and network monitoring, what each catches, and what to do when one fires.
9 min readUpdated Sep 5, 2026
Change Management for OT
A change process sized for a utility control system: what counts as a change, the request with risk and rollback, owner approval, the window, backup before and verification after, the baseline update, the emergency path, and the record.
9 min readUpdated Sep 5, 2026
Isolating a Compromised System
Cutting a compromised machine, segment, or site off from the control system without stopping the process: who may decide, isolation points planned in advance, disconnecting the network rather than the power, running on manual control, and preserving evidence.
9 min readUpdated Sep 5, 2026
Recovery and Restoration
Bringing a control system back after a compromise without reintroducing it: controllers verified against baselines first, servers rebuilt from clean media and project exports, every credential changed, hardening, staged reconnection, and end-to-end tests.
9 min readUpdated Sep 5, 2026
Advisories and Alerts
Where a utility learns its equipment has a known vulnerability and what to do with the news: the government and vendor advisory feeds, the sector center, the exploited catalog, subscribing by product, a weekly triage on exposure and consequence, and records.
8 min readUpdated Sep 5, 2026
Risk-Based Patching
Deciding what to patch first when everything cannot be patched at once: priority from exposure, exploitation, and consequence rather than scores, tiers with timelines, different rules for servers, network gear, and controllers, and the written accept decision.
8 min readUpdated Sep 5, 2026
AWIA Requirements
What the 2018 water infrastructure act requires of community water systems: a risk and resilience assessment and an emergency response plan, certified on a schedule by size and repeated every five years, with cybersecurity named in both, and who is covered.
9 min readUpdated Sep 5, 2026
Data Diodes
Hardware that lets data flow one way only, from the control network outward, with no physical return path: what a data diode and a unidirectional gateway are, where they belong, what they can and cannot carry, and when a firewall is enough instead.
8 min readUpdated Sep 5, 2026
Multi-Factor Authentication
Requiring a second proof of identity beyond a password, where it matters most in a control system and how to do it without locking an operator out: the factor types, where it is mandatory, where it does not fit, enrollment and recovery, and vendor accounts.
8 min readUpdated Sep 5, 2026
Session Logging
Recording every remote session into the control system: who connected, from where, when, to what, and what they did, from the VPN log through jump host session recording to the SCADA audit trail and controller change log, stored off the systems and reviewed.
8 min readUpdated Sep 5, 2026
How to Add an Alarm
From a request to a working alarm: define it against the philosophy, build the condition in the PLC with deadband and delays, configure the SCADA alarm with priority and message, test it end to end, and record it in the master alarm database.
9 min readUpdated Sep 5, 2026
How to Diagnose a Bad Quality Tag
Trace a bad quality indication from the SCADA screen back to its source: the tag configuration, the driver and device connection, the controller tag, and the field signal, using the diagnostics each layer provides, and separate a stale value from a bad one.
8 min readUpdated Sep 5, 2026
How to Build a Tag
Create a SCADA tag that is correct, documented, and consistent with every other tag: name it by the convention, bind it to the right controller address or name, and verify it against the live value and the I/O list before it goes on a screen.
7 min readUpdated Sep 5, 2026
How to Configure Alarms
Configure alarms in the SCADA system from the alarm list: set the source, controller-generated or evaluated in SCADA, the limits and deadband and delay, and the notification; then test each alarm end to end and review the alarm rate after the first weeks.
8 min readUpdated Sep 5, 2026
How to Trend Data
Build trends that operators use: choose the tags that tell one story per trend, set scales and time spans that show the behavior, and make ad hoc trending fast enough that an operator reaches for it before a phone call.
7 min readUpdated Sep 5, 2026
How to Configure a Historian
Set up a process historian that collects what matters and keeps it: decide the tags and their classes, set collection intervals and deadbands per class, size the storage and the retention, and hand the operators a working trend on day one.
8 min readUpdated Sep 5, 2026
How to Build Pump Graphics
Build a pump symbol and faceplate that operators can read at a glance and use without error: a symbol that shows state by shape and a muted palette with color reserved for abnormal, and a test against the high-performance HMI principles before it is deployed.
8 min readUpdated Sep 5, 2026
How to Configure Remote Access
Give operators and engineers a way into the SCADA system from outside that does not give it to anyone else: a virtual private network with multi-factor authentication terminating in a demilitarized zone, and a test that proves the path works and that the.
8 min readUpdated Sep 5, 2026
Values Frozen On Screen
The HMI shows numbers that are not changing while the plant runs. Whether the controller, the communication driver, the tag server, or the display stopped, and the order to check them in.
7 min readUpdated Sep 5, 2026
Tag Shows Bad Quality
A tag flagged bad or uncertain by the driver. What the quality codes mean, the difference between a device that is not answering and an address that does not exist, and how to clear each.
7 min readUpdated Sep 5, 2026
Alarms Not Annunciating
The condition is real and nothing happened on the screen or the phone: where an alarm can be lost between the controller and the operator, from the alarm bit and the tag quality to the alarm server, the display filter, the shelved and suppressed lists, the audible, and the notifier.
9 min readUpdated Sep 5, 2026
UPS Not Carrying Load
The power failed and the controls went down anyway: a battery aged out or never connected, a UPS sitting in bypass since a fault, an overload, loads on the wrong receptacles, or a failed self-test nobody read. Finding out which, and testing properly.
8 min readUpdated Sep 5, 2026
Remote Site Stops Communicating
One radio site silent while its neighbors answer: site power, the radio, antenna and coax after a storm, a reset configuration, the controller behind it, or a changed path. What the master diagnostics say before anyone drives, and the order of checks on site.
8 min readUpdated Sep 5, 2026
Intermittent Radio Path
A site that drops and returns by the hour, season, or weather: thin fade margin, foliage, a new obstruction, a loosened antenna, coax taking water, a corroding connector, interference, or a marginal supply. How to trend signal against time and weather.
8 min readUpdated Sep 5, 2026
High Retry Count
Polls that succeed on the second or third try: a weak or noisy path, interference, collisions from a second master, a timeout shorter than the radio turnaround, a data rate the path cannot carry, or a slow controller. Reading retry statistics per site.
8 min readUpdated Sep 5, 2026
Data Plan or APN Problems
A modem that registers but has no data, or runs out mid-month: a wrong or changed APN, a capped or throttled plan, a module on the wrong plan or network, a missing static address, or polling that uses more data than planned. Sizing a plan, cutting traffic.
8 min readUpdated Sep 5, 2026
Fiber Link Down
A fiber link with no light: a cut or crushed cable, a failed or unseated transceiver, a reversed patch cord, a dirty connector, a disabled port, a mismatched module pair, or a dead media converter. Reading port state and optical power to find the break.
8 min readUpdated Sep 5, 2026
Intermittent Fiber Link
A fiber link that flaps: down for seconds and back, worse at night, in the cold, in wind, or when a door opens. No margin, a nearly seated connector, a failing or hot transceiver, a moving bend, water freezing in a splice case, or a port flapping on its own.
8 min readUpdated Sep 5, 2026
Intermittent Packet Loss
Polls that occasionally fail, tags that flicker bad, a ping that drops one in fifty: a bad cable or port, a duplex mismatch, a saturated link, a buffer overrun, a marginal radio or fiber hop, a slow device, or a loop. Finding which hop loses packets and why.
9 min readUpdated Sep 5, 2026
Cannot Ping Across VLANs
Two devices that work on their own networks but cannot reach each other across a VLAN boundary: no route, a wrong or missing gateway, a mask that puts the target on the wrong side, a trunk missing the VLAN, or a firewall rule. Testing each in order.
8 min readUpdated Sep 5, 2026
Duplicate IP Address
Two devices claiming one address: a controller that answers sometimes, a workstation that reports a conflict, a ping returning from two hardware addresses. Where duplicates come from, finding both in the switch address table, and the discipline that stops it.
7 min readUpdated Sep 5, 2026
Broadcast Storm
A network suddenly slow or dead everywhere, every link light solid: a loop between switches without protection, a failed ring protocol, or a device flooding broadcasts. Recognising a storm, breaking it with a cable pull, finding the loop, and preventing it.
8 min readUpdated Sep 5, 2026
Trend Gaps
Holes in a trend where data should be: a communication loss, a historian that stopped or fell behind, a buffer that filled or never forwarded, compression set too coarse, a renamed tag, or a clock that jumped. Reading the cause from the shape of the gap.
8 min readUpdated Sep 5, 2026
Client Cannot Connect
A workstation, web, or mobile client that cannot reach the SCADA server: the service down, a firewall path closed, a license or session limit, a certificate or name failure, a version mismatch after an update, or expired credentials. Testing each layer.
8 min readUpdated Sep 5, 2026
Duplicate or Missing History
A historian with two records for one moment, or none: a redundant pair both collecting, a buffer that forwarded twice, a tag under two names, a daylight saving shift, or a source that resends on reconnect. Cleaning the record without inventing data.
8 min readUpdated Sep 5, 2026
Read Works but Write Fails
Polling a device returns good data and writing a setpoint does nothing or returns an exception: a write-protected device, a read-only register, the wrong function code, a wrong address or type, logic that overwrites the value, a security rule, or a local mode.
8 min readUpdated Sep 5, 2026
Protocol Gateway Stops Passing Data
The gateway is powered and pingable and the data behind it is frozen or gone: the device side failed while the master side answers, a stalled gateway, configuration lost on a power cycle, a stale mapping, or a master polling too fast. Testing each side.
8 min readUpdated Sep 5, 2026
Startup Checklist
The checklist for bringing a control system and its process into operation after commissioning or an outage: verification of power, I/O, communications, setpoints, forces, and backups; staged energization; manual first, then automatic; and the watch.
8 min readUpdated Sep 5, 2026
Troubleshooting Checklist
A general checklist for any control system problem, usable at 2 a.m.: define the problem, ask what changed, make the process safe, gather the evidence before touching anything, divide the chain, change one thing at a time, restore, and record.
8 min readUpdated Sep 5, 2026
NIST Publications for Control Systems
The National Institute of Standards and Technology documents a control engineer will meet: the Cybersecurity Framework, the operational technology security guide, the control catalog, the digital identity guideline, and the incident handling guide.
9 min readUpdated Sep 5, 2026
Where the Logic Should Live: Controller, SCADA, or Relay
Every control decision has a home, and putting it in the wrong one is the root of most plants that are hard to operate. A rule for deciding what belongs in the controller, what belongs in SCADA, and what belongs in a relay.
9 min readUpdated Sep 5, 2026
What a Small Utility Should Ask Before Buying SCADA
A utility with a plant, a few dozen remote sites, and two operators on call is buying a system it will live with for twenty years. The questions that decide whether it works out, and they are not about features: licensing, staffing, and the exit.
9 min readUpdated Sep 5, 2026
The Tank Level Trend Tells the Whole Story
One trend, a storage tank level over a week, holds most of what an operator needs to know about a water system: demand, source capacity, leaks, pump health, water age, and why it deserves a permanent place on the main screen.
8 min readUpdated Sep 5, 2026
Alarms Nobody Answers
A SCADA system that raises eight hundred alarms a day has trained its operators to ignore it. How a small plant gets there, what the standing alarm list is telling you, and a one-day rationalization that gives the alarm system its voice back.
9 min readUpdated Sep 5, 2026
Inflow and Infiltration Shows Up in the Pump Runtime
Most small collection systems have no flow meters at the lift stations, but every station reports pump runtime and starts to SCADA. How to turn those two numbers into a station flow estimate, and rank where the money for pipe work should go.
9 min readUpdated Sep 5, 2026
One Flat Network Is One Big Fault Domain
A looped patch cable in an office closet took down every PLC at the plant, because the office and the plant were one network. Why a flat network makes every fault a plant-wide fault, and how to get there one switch at a time.
9 min readUpdated Sep 5, 2026
The Vendor Laptop Is on Your Network Now
Every service call ends with a laptop plugged into the control network, and most utilities have no rule about it. What can go wrong when a vendor connects, and how to have the conversation without losing the vendor.
9 min readUpdated Sep 5, 2026
The Intermittent Fault Is a Data Problem
A fault that happens once a week at random cannot be found with a meter, because it is never happening while the meter is connected. How to turn an intermittent problem into a recorded one, and how the patterns in the record point at the cause.
9 min readUpdated Sep 5, 2026
ISA-18.2 Alarm Management
The lifecycle standard for alarm systems, the rate targets that define a workable system, and why alarm rationalization is the step nobody wants to fund.
10 min readUpdated Aug 15, 2026
What Is SCADA?
Supervisory control and data acquisition: the layer that collects data from controllers across a system, presents it to operators, records it, and lets them intervene.
9 min readUpdated Aug 4, 2026
High Performance HMI Design
Grey backgrounds, reserved color, and displays designed to make abnormal conditions obvious rather than to look impressive in a demo.
8 min readUpdated Jul 24, 2026
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Content on CurryControls.com is general technical reference information provided for educational and reference purposes only. It is not engineering advice for a specific installation. All information must be independently verified against current codes, standards, manufacturer documentation, project requirements, and qualified professional judgment before it is relied upon or applied.