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Modbus Integration

Tinkwell includes a built-in Modbus client that polls RTU (serial/RS-485) and TCP devices, decoding register values and feeding them directly into the measures system. No external bridge scripts are needed.

Configuration

Declare modbus blocks in your .tw ensemble file:

RTU (serial)

modbus cnc-sensors {
    transport = rtu
    port = "/dev/ttyUSB0"
    baudrate = 9600

    device 1 {
        poll-interval = "1 second"

        register spindle-vibration {
            address = 0x0000
            type = float32-be
        }

        register spindle-temp {
            address = 0x0010
            type = int16
            scale = 0.1
        }
    }
}

TCP

modbus plc {
    transport = tcp
    host = "192.168.1.100"
    tcp-port = 502

    device 1 {
        poll-interval = "500 ms"

        register output-pressure {
            address = 100
            type = float32-be
        }
    }
}

Connection properties

Property Default Description
transport rtu rtu (serial) or tcp
port — Serial port name (RTU only, e.g. /dev/ttyUSB0, COM3)
baudrate 9600 Serial baud rate (RTU only)
host localhost TCP hostname or IP (TCP only)
tcp-port 502 TCP port (TCP only)

Device properties

Property Default Description
(name) — Modbus slave ID (1–247)
poll-interval 1 (second) How often to read registers. Accepts "500 ms", "2 seconds", or a plain number (seconds).

Register properties

Property Default Description
(name) — Block name = measure name (unless measure is set)
address — Register address (decimal or 0x hex)
type int16 Data type for decoding (see table below)
kind holding holding (FC 03) or input (FC 04)
scale 1.0 Multiplier applied after decoding
measure (block name) Measure to update (overrides block name)

Data types

Type string Registers Byte order Description
int16 1 — Signed 16-bit
uint16 1 — Unsigned 16-bit
int32-be / int32 2 ABCD Signed 32-bit, big-endian
int32-le 2 DCBA Signed 32-bit, little-endian
uint32-be / uint32 2 ABCD Unsigned 32-bit, big-endian
uint32-le 2 DCBA Unsigned 32-bit, little-endian
float32-be / float32 / float 2 ABCD IEEE 754 float, big-endian (most common)
float32-le 2 DCBA IEEE 754 float, little-endian
float32-ws / float32-swapped 2 BADC IEEE 754 float, word-swapped (Schneider/Modicon PLCs)

Runlet setup

Add the Modbus runlet to a headless runner in your ensemble:

runner background from "Tinkwell.Runner.Headless.dll" {
    runlet modbus from "Tinkwell.Runlet.Modbus.dll";
}

The runlet discovers the measures gRPC service automatically. Make sure the measures runner starts before the Modbus runner (declare it earlier in the ensemble).

CLI commands

For manual testing and debugging:

# Read 2 holding registers as a float from a TCP device
tw modbus read 0x0000 --count 2 --type float32-be --host 192.168.1.100

# Read 1 input register via RTU
tw modbus read 0x0010 --transport rtu --port COM3 --slave 1 --input

# Write a single register
tw modbus write 0x0064 1234 --host 192.168.1.100

See the CLI reference for full options.

Library API

The Tinkwell.Modbus NuGet package provides the standalone protocol library for use outside of Tinkwell. See the library README for C# examples.