Guides
Automation and instrumentation guides
How current loops carry a measurement to a PLC, how milliamps become engineering units, how to tune a PID loop, wire a PT100, turn a level into litres, choose between a PLC, a microcontroller and an industrial PC, and make Modbus behave: the fundamentals behind our automation work.
Written from commissioning notes rather than textbooks. Each guide explains one part of a control system well enough to fault-find it, and pairs with an automation calculator that does the arithmetic.
How 4–20 mA current loops work
Why process signals are currents rather than voltages, why zero is 4 mA, what sits in a loop and how much voltage it needs, how a PLC scales milliamps into bar and raw counts, the NAMUR NE 43 fault bands, grounding and shields, and when a plain loop still beats a fieldbus.
Read guide →How to size a pump motor
Flow, head and the duty point; hydraulic power and why head is not pressure; pump efficiency and the best efficiency point; margins, IEC ratings and the run-out case; motor efficiency, current and the cable; specific energy per cubic metre; and what a variable-speed drive changes.
Read guide →PID tuning from a step test
What P, I and D each do; how to bump a loop in manual and read K, τ and θ off the trend; what the Ziegler–Nichols and SIMC rules are designed for; the ultimate-gain test and autotuners; the vendor forms and units that trip people; fine-tuning afterwards; and the loops these rules do not fit.
Read guide →PT100 sensors and wiring
Why platinum and why 100 Ω; the Callendar–Van Dusen curve; what 2-, 3- and 4-wire connections do about lead resistance; immersion, thermowells and response time; self-heating; tolerance classes against installed accuracy; head-mounted transmitters; and fault-finding a PT100 loop with a multimeter.
Read guide →Level measurement and tank volume
A transmitter reports a height and the plant wants litres: the geometry of vertical, horizontal and dished tanks; hydrostatic, ultrasonic, radar, float and capacitance transmitters and where each fails; PLC scaling by formula or strapping table; alarms, overfill protection and installation details.
Read guide →PLC, microcontroller or industrial PC
What a PLC, a custom microcontroller board and an industrial PC each give you and cost you; the questions that decide (I/O, safety, timing, quantity, maintenance, lifetime, integration); the combinations that work; spares, technicians, heat and power in Pakistan; three typical examples.
Read guide →Modbus RTU and TCP explained
One master, many slaves and four register tables; the off-by-one in addressing; 32-bit values and word order; the RTU frame, CRC and timing; RS-485 wiring, termination and bias; Modbus TCP and gateways; how many registers a second a bus carries; diagnostics; where Modbus is the wrong tool.
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