Control System Calc vs OT Toolbox

Control System Calc (ControlCalc) is an engineering tool for control engineers, R&D staff and students. Enter a transfer function to perform PID tuning, frequency-domain analysis and time-domain simulation — turning textbook control theory into a pocket tool you can use anywhere. All calculations run locally on your device, no internet required. KEY FEATURES ■ PID Tuning Five classic tuning methods built in: Ziegler-Nichols open-loop step, Cohen-Coon, Ziegler-Nichols closed-loop ultimate, plus IMC-Lambda and AMIGO. Each method includes guidance on when to use it. ■ Closed-Loop Step Simulation Simulate the closed-loop step response with an FOPDT model and a PID controller with derivative filtering. View the control effort u(t) to spot actuator saturation, and fine-tune parameters by hand. ■ Bode Plot & Stability Margins Draw magnitude and phase curves on a log scale, with automatic 0 dB / −180° reference lines, gain margin, phase margin and crossover frequencies — stability at a glance. ■ Step Response & Performance Metrics RK4 time-domain simulation that automatically computes overshoot, rise time and settling time. ■ Second-Order Designer Back-solve system parameters from overshoot Mp / settling time ts, or from damping ratio ζ / natural frequency ωn, then push them to the step-response page in one tap. ■ Root Locus & Nyquist (Pro) Root-locus branch tracing with the imaginary-axis stability boundary, an equal-aspect Nyquist plot with unit circle, plus pole/stability analysis for deeper insight. THOUGHTFUL DETAILS • Built-in library of classic example models — tap to load and go • Draggable readouts on time-domain curves (live t / y display) • Numeric keyboard with a Done button; input parameters persist automatically • Simplified Chinese / English / German / Japanese, switchable in-app instantly PRO UPGRADE (one-time purchase) • Removes all ads • Unlocks IMC-Lambda / AMIGO tuning methods • Unlocks Nyquist plot, root locus and pole/stability analysis • Unlocks CSV data export Buy once, keep forever. Family Sharing supported. WHO IS IT FOR Control, electrical, mechatronics and process engineers, R&D and commissioning staff, students taking control-theory courses, and anyone who needs to quickly validate a control-system design. DISCLAIMER All results are provided for engineering reference only. Real-world system design and commissioning should combine field conditions with professional judgment. Have feedback or questions? Contact us from the Settings page.

OT Toolbox is a compact collection of practical tools for automation, controls engineering, commissioning, maintenance, and industrial service. Instead of searching through formulas, tables, and separate apps, keep essential OT calculations organized in one place – directly on your iPhone and without an account. NETWORKING AND INDUSTRIAL COMMUNICATION • IPv4 subnet calculator with network, broadcast, host range, and wildcard • IP comparison plus CIDR and subnet-mask conversion • IP planning, device inventory, and port reference • PROFINET device-name validation • OPC UA endpoint builder • Data-rate, transfer-time, and Ethernet frame-budget calculations SIGNALS AND INSTRUMENTATION • Linear scaling for analog values and PLC raw values • 4–20 mA troubleshooting, loop budgeting, and measurement-error estimation • PT100 resistance and temperature conversion • PT100 lead-wire error estimation • RC low-pass and ADC resolution calculations PLC, DATA, AND MODBUS • Binary, decimal, and hexadecimal conversion • Bit masks and two's-complement representation • Modbus address and FLOAT32 data conversion • Register-block planning and RTU timing • PLC time formats, watchdog sizing, memory demand, and cycle-load analysis ELECTRICAL AND ENERGY • Ohm's law plus active, apparent, and reactive power • Voltage drop and cable losses • 24 V DC power-supply sizing with reserve • UPS runtime and capacitor backup estimation • Energy consumption and operating-cost calculations DRIVES AND PNEUMATICS • Motor speed, motor torque, and gearbox calculations • Encoder resolution, positioning accuracy, and conveyor speed • Drive ramps and braking energy • Air consumption, cylinder force, and valve-island reserve SERVICE AND PRODUCTION • Unit, time, and cycle-time conversion • OEE and MTBF/MTTR availability • Maintenance-interval forecasting • Guidance calculation for safety distance • Formula reference for recurring tasks BUILT FOR DAILY FIELD WORK Clear field labels, units, and contextual help show exactly what to enter. Favorites, history, and templates bring frequently used tools back quickly. Colleague Mode presents results clearly and makes technical calculations easier to share. PRIVACY WITHOUT FRICTION Technical inputs stay locally on your device. No account, no tracking, and no ads. A selection of core tools is available for free. OT Toolbox Pro permanently unlocks advanced calculators and productivity features with one in-app purchase – no subscription. Important: Results are calculation aids. Manufacturer documentation, applicable standards, safety requirements, and review by qualified professionals always take priority.