Engineering Resources
Working reference material for people who commission, maintain, and monitor industrial control systems. Everything here is free to read, print, and share - no form, no email gate. Each resource stands on its own and cites the primary standards it draws from. For guided reading orders, see the learning paths at Automation University, or browse the video library.
PLC Commissioning Checklist
Seven phases from pre-job preparation to documentation handover: I/O checkout, comms verification, fail-state behavior, and alarm testing, each as a working checklist you can run on screen or print.
Open the checklist → Reference TableIndustrial Protocol Selection Matrix
Modbus RTU/TCP, DNP3, OPC UA, MQTT Sparkplug, EtherNet/IP, HART, and BACnet compared across transport, comms model, report by exception, time-stamping, and security - plus a short decision sequence.
Open the matrix → WorksheetAlarm Rationalization Worksheet
A worksheet for deciding what actually deserves to be an alarm, built on the alarm-management lifecycle concepts behind ISA-18.2, with a worked example and a blank template you can copy.
Open the worksheet → ChecklistInstrumentation Loop Check Checklist
Follows each signal from the field device through wiring and marshalling to controller I/O and the HMI: 5-point checks, fail-direction verification, alarm limit checks, and sign-off documentation.
Open the checklist → Decision GuideRemote Monitoring Architecture Guide
How to pick an architecture for remote sites: decision factors from power budget to security posture, a reference architecture diagram, and a cellular vs satellite vs radio trade-off table.
Open the guide →These references pair naturally with the longer guides on the blog. The commissioning checklist, for example, picks up where the panel shop leaves off - the wiring, labeling, and factory acceptance testing described in our guide to industrial control panel fabrication all happen before the first field checkout item is ticked.
Calculators
Interactive engineering calculators that run entirely in your browser: enter your numbers and read the result, with the formula and a worked example shown on every page. Nothing is stored or sent anywhere. Each result is an engineering estimate to verify against manufacturer data and site measurements.
4-20 mA Scaling Calculator
Convert between a 4-20 mA loop current and its process value in either direction, with percent of span, from the LRV and URV of a scaled instrument.
Open the calculator → CalculatorLoop Voltage Headroom Calculator
Check whether a 4-20 mA loop has enough supply voltage for the transmitter after wire, sense, and barrier drops at worst-case current.
Open the calculator → CalculatorPt100 Resistance-Temperature Calculator
Convert between Pt100 RTD resistance and temperature using the IEC 60751 coefficients, over the sensor's rated range, in both directions.
Open the calculator → CalculatorCable Voltage Drop Calculator
Estimate the round-trip voltage drop on a copper cable run from wire gauge, length, and current, using per-1000-ft resistance at 20 C.
Open the calculator → CalculatorHorizontal Tank Volume Calculator
Turn a measured level into a liquid volume for a horizontal cylindrical tank, with gallons, barrels, and percent full for the cylindrical body.
Open the calculator → CalculatorVertical Tank Volume Calculator
Compute the volume in a vertical cylindrical tank from level, plus a 10-row level-to-volume table for the tank dimensions you enter.
Open the calculator → CalculatorEngineering Unit Converter
Convert the mixed process units on datasheets and screens: pressure, temperature, volume, flow, and power, with every factor shown.
Open the converter → CalculatorOrifice Beta Ratio Calculator
Compute the orifice plate beta ratio and velocity-of-approach factor from bore and pipe diameter, and flag beta outside common practice.
Open the calculator → CalculatorBattery Autonomy Calculator
Estimate how long a battery bank runs a remote load from amp-hours, voltage, depth of discharge, and load, in hours and days.
Open the calculator → CalculatorSolar Array Sizing Estimator
Estimate the solar array wattage an off-grid site needs from daily load, your local peak sun hours, and a system derate factor.
Open the estimator → CalculatorHART Loop Resistance Calculator
Sum the series resistance in a HART loop and compare it against the common 230 to 1100 ohm HART communication window.
Open the calculator → CalculatorTelemetry Data Usage Estimator
Estimate monthly cellular data for a telemetry site from tag count, bytes per sample, polling interval, and protocol overhead.
Open the estimator →How These Resources Are Maintained
These pages are written and maintained by the Merobix engineering team in an organization voice. They describe common industry practice, not the requirements of any specific site, standard, or regulator - always defer to your own site procedures and to the primary sources cited on each page. Where a value is genuinely site-specific, the resource says so instead of inventing a number.
If you spot a technical error, we want to know. Report it through our corrections page and we will review it against the primary sources.
Sources & Standards
The organizations and reference documents cited most often across these resources:
- International Society of Automation (ISA) - standards for alarm management, documentation, and control system security.
- International Electrotechnical Commission (IEC) - international standards for industrial-process measurement, control, and automation.
- NIST SP 800-82 Rev. 3 - the Guide to Operational Technology (OT) Security.
- CISA - U.S. Cybersecurity and Infrastructure Security Agency guidance for industrial control systems.
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