# Modbus TCP

A connection type for [`ModbusDevice`](https://dev.nominal.io/instro/library/protocols/modbus.md)

![Modbus TCP](https://dev.nominal.io/instro/_images/ModbusTCP.png)

Modbus TCP is a connection type for [`ModbusDevice`](https://dev.nominal.io/instro/library/protocols/modbus.md), not a separate driver class: set `"transport": "tcp"` in the config’s connection block, or pass a `ModbusTCPTransport` explicitly.

## Creating a [`ModbusDevice`](https://dev.nominal.io/instro/ref/protocols/instro.modbus.ModbusDevice.md#instro.modbus.ModbusDevice "instro.modbus.ModbusDevice") over TCP

```python
from instro.modbus import ModbusDevice

# connection block declared inline, e.g. { "transport": "tcp", "host": "192.168.1.100", "port": 502 }
device = ModbusDevice(config="my_device.json")
device.open()
```

Or with an explicit, shareable transport:

```python
from instro.lib.transports import ModbusTCPTransport
from instro.modbus import ModbusDevice

transport = ModbusTCPTransport(host="192.168.1.100", port=502)
device = ModbusDevice(config="my_device.json", connection=transport, unit_id=1)
```

Parameters and methods specific to [`ModbusDevice`](https://dev.nominal.io/instro/ref/protocols/instro.modbus.ModbusDevice.md#instro.modbus.ModbusDevice "instro.modbus.ModbusDevice") can be found in the [Reference](https://dev.nominal.io/instro/ref.md).