Serial Port

Serial channels connect USB-to-serial adapters, RS232/RS485 converters, and other devices exposed as COM ports. Zeus opens, closes, writes, and raises receive events so you do not need to use System.IO.Ports.SerialPort directly.

Confirm Three Things First

Check	Example	Where to find it
Port name	COM3	Windows Device Manager
Parameters	9600, 8N1	Device manual or field configuration
Protocol	Raw bytes, custom frame, Modbus RTU	Device protocol manual

Knowing only the COM port is not enough. A wrong baud rate, parity, stop bit, or protocol may still let the port open but return invalid data.

Minimal Usage

await using var app = ZeusHost.Create(builder =>
{
    builder.AddSerialPort("meter", "COM3", 9600);
});

var meter = app.Channels.Get("meter");
meter.DataReceived += (_, e) =>
{
    Console.WriteLine(Convert.ToHexString(e.Data.Span));
};

await app.StartAsync();
await meter.WriteAsync(new byte[] { 0x01, 0x03, 0x00, 0x00, 0x00, 0x02, 0xC4, 0x0B });

meter is the Zeus channel name; COM3 is the operating-system port name.

Full Options

builder.AddSerialPort("meter", options =>
{
    options.PortName = "COM3";
    options.BaudRate = 9600;
    options.DataBits = 8;
    options.Parity = System.IO.Ports.Parity.Even;
    options.StopBits = System.IO.Ports.StopBits.One;
    options.ReadTimeoutMilliseconds = 500;
    options.WriteTimeoutMilliseconds = 500;
});

Option Meaning

Option	Default	Meaning
PortName	COM1	OS-visible port name
BaudRate	115200	Bits per second; must match the device
DataBits	8	Data bits, usually 8
Parity	None	None / Even are common
StopBits	One	Usually one stop bit
ReadTimeoutMilliseconds	1000	Read timeout
WriteTimeoutMilliseconds	1000	Write timeout

Pairing with Protocols

Device protocol	Recommended approach
Manual gives fixed hex commands	Use WriteAsync and process DataReceived
Header + length + checksum	Use Custom Framing
Modbus RTU	Use Modbus; do not hand-build CRC
Omron Host Link	Use Omron Host Link

Common Issues

Symptom	Likely cause	Fix
Port is busy	Another program owns it	Close serial tools and retry
COM3 not found	Port changed or driver is missing	Check Device Manager
Port opens but no data	Wiring, baud rate, parity, or device behavior	Verify with a serial tool
Garbled text	Binary protocol displayed as text	Inspect raw bytes with Convert.ToHexString
Modbus timeout	Unit id, function code, RTU/TCP mode, or CRC issue	Test with a virtual Modbus slave first

Without hardware, keep using Virtual Channel.