PortDock Modbus Slave
Turns the PC into a Modbus slave (serial RTU, or a Modbus TCP or RTU over TCP server) so you can test a master (PLC, HMI, host software) without the real device — including deliberate delays and errors.
Made for
- Developers writing a Modbus master
- Teams preparing HMI screens before the device arrives
Features
Three transports
Serial (RTU), TCP server (Modbus TCP) and TCP server (RTU over TCP — a device behind a serial device server).
Four tables
Coils, discrete inputs, holding and input registers. View a table as U16, S16, HEX or BIN, set per-cell U32, S32, F32, F64 or string types with byte order, and let values change by themselves (increment, random, sine …).
Several Slave IDs
Run several Slave IDs (1–247), each with its own values.
Fault injection
Delay, no response, broken CRC, wrong MBAP length or forced exceptions — targeted by Slave ID, function, address, every Nth request or probability — to test the master's timeouts and retries.
See every write
Cells written by the master flash, with a traffic log and statistics.
Device profiles, saved tables
Load register names and types of 10 built-in devices (inverters, temperature controllers, power meters …) with example values. Export and import tables as CSV register maps (same format as Modbus Master) or JSON.
Quick start
- Pick the transport (serial or TCP) and port and baud rate (or address and port); add Slave IDs if needed
- Choose a table, set start and count, enter values
- «Connect» («Start» for TCP) — master requests are answered from the table