FieldSim - Protocol Simulator

Fieldsim turns your iPhone into a real industrial and IoT protocol test bench — no extra hardware, no lab PC, no separate test tools.

Fieldsim isn't a mock-up. Every protocol is implemented against its real wire-level specification and verified against industry-standard reference clients and libraries. Real SCADA software, PLCs, and IoT gateways can connect to your iPhone and talk to it exactly as they would to a real field device.

Simulate 11 real protocols: • MQTT — full broker with multi-topic publish/subscribe • OPC UA — session/subscription server with a real address space • Modbus TCP — coils, discrete inputs, holding & input registers • BACnet/IP — Who-Is/I-Am discovery, ReadProperty/WriteProperty • DNP3 — link/transport/application layers, Class 0 polling, Direct Operate • EtherNet/IP — CIP explicit messaging (Get/Set_Attribute_Single) • SNMP v2c — GET/GETNEXT/SET plus trap notifications • AMQP 0-9-1 — full exchange/queue/consumer message broker • CoAP — RFC 7252 with the Observe extension for live push updates • HART-IP — session-managed Pass-Through with Universal Commands • LoRaWAN — a real Network Server speaking the Semtech UDP protocol, with AES-128/CMAC frame encryption and authentication

Every protocol, both directions. Each simulator supports multiple simultaneous tags, points, or objects — build out a small virtual plant, not just one sensor. And every protocol also has a matching built-in client on the Client tab, so you can test your simulator (or any other real device on your network) without installing a second app or opening a terminal.

Built for real testing, not demos: • Live, scrollable activity logs for every simulator and client • Save and reuse connection presets per protocol — host, port, credentials, and protocol-specific settings • Automatic detection of your iPhone's network address, so external clients always know where to connect • Configurable value patterns (random, sine wave, ramp, static) for realistic simulated data

Who it's for: Automation and controls engineers validating SCADA/HMI integrations, QA teams testing IoT gateways and protocol converters, product developers building device firmware against real-world protocols, and students or instructors learning how industrial protocols actually work on the wire.

Fieldsim is iOS-native, built entirely on Apple's Network framework — fast, lightweight, and works over Wi-Fi with any device on the same network.

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