pySerialMux

Drop-in 1-to-N multiplexer for pyserial hardware serial interfaces.

Quick usage

from pySerialMux import Serial

with Serial("/dev/ttyUSB0", baudrate=115200, timeout=1.0) as ser:
  ser.write(b"hello\n")
  print(ser.readline())

On-demand QoL and debug options

The proxy accepts optional flags through Serial(...):

• debug=True
  Enables debug logging for proxy/broker lifecycle details.

• logs=True
  Enables global binary message logging. The client will receive and buffer all serial and client-to-client traffic with timestamps and origin IDs.

• ignore_baudrate_diff=True
  Allows a client to connect even when its requested baudrate differs from the broker's baudrate.

• virtual_interface="<name>"
  Enables virtual routing mode for that interface name.

• client_id="<id>"
  Optional, but required when using virtual_interface or target_id features.

• target_id="<id>"
  Routes all writes directly to the client with the matching client_id instead of physical serial. This client will also be isolated from general serial broadcasts.

• host_virtual_interface=True
  Marks the client as host for that virtual interface. Non-host clients writing to that interface are routed to the host client instead of physical serial.

Client-to-client targeting

Clients can communicate directly by using target_id:

# Setup two clients
alpha = Serial("COM1", client_id="Alpha", target_id="Beta")
beta  = Serial("COM1", client_id="Beta",  target_id="Alpha")

alpha.write(b"Hello Beta")
print(beta.read(10)) # b'Hello Beta'

Runtime targeting

You can change or clear the target at any time:

ser = Serial("COM1", client_id="Alpha")
ser.target_id = "Beta" # Now talking to Beta
ser.target_id = None   # Back to physical serial

Targeted writes

Use the target_id keyword argument for one-off targeted messages:

ser.write(b"One-off message", target_id="Beta")

Discovery and Shared State

Client Discovery

Access a live list of other connected clients:

print(ser.other_clients) # ['Beta', 'Gamma']

Shared Data Store

Share state information between all clients:

# Client Alpha
ser.set_shared("status", b"active")

# Client Beta
print(ser.shared.get("status")) # b'active'

Global Logging

When logs=True is enabled, the broker aggregates all traffic (serial and client-to-client) with high-precision timestamps and origin IDs.

Accessing logs

Retrieve all buffered log entries:

# Returns a list of dicts:
# [{'timestamp': float, 'origin_type': OriginType, 'origin_id': str, 'direction': Direction, 'data': bytes}, ...]
# direction is Direction.TX (leaving the broker) or Direction.RX (entering the broker).
logs = ser.get_logs()

Real-time logging

Hook into every message as it arrives:

def my_logger(entry):
    print(f"[{entry['timestamp']}] {entry['origin_id']} {entry['direction'].name}: {entry['data']}")

ser.on_log = my_logger

Runtime control

You can enable or disable logging at any time:

ser.logs = True  # Start receiving logs
ser.logs = False # Stop receiving logs

Virtual interface example

# host side
host = Serial(
    "/dev/ttyUSB0",
    virtual_interface="lab-bus",
    client_id="host-1",
    host_virtual_interface=True,
)

# client side
client = Serial(
    "/dev/ttyUSB0",
    virtual_interface="lab-bus",
    client_id="client-1",
)

client.write(b"message to host")
print(host.read(15))