Virtual Serial Port Router (vsp-router)

Create virtual serial ports, connect them to physical serial ports, and create routes between them all.

Vsp-router was created to connect two terminal emulators to the same physical RS-232 serial console.

Supported Operating Systems

• Linux: Yes, tested on Red Hat Enterprise Linux 8
• macOS: Yes, tested on macOS Ventura 13.1
• Windows: Yes*, tested on Windows 10

*The Windows version does not support creation of virtual serial ports. A third-party tool like com0com can be used instead.

Use Cases

Multiplex two virtual serial ports to a single physical serial port.

vsp-router \
    --create 0 \
    --create 1 \
    --attach 2:/dev/ttyUSB0 \
    --route 0:2 \
    --route 1:2 \
    --route 2:0 \
    --route 2:1

Multiplex two virtual serial ports to a third virtual serial port.

vsp-router \
    --create 0 \
    --create 1 \
    --create 2 \
    --route 0:2 \
    --route 1:2 \
    --route 2:0 \
    --route 2:1

Example

In terminal A

cargo run -- \
    --create 0 \
    --create 1 \
    --create 2 \
    --route 0:2 \
    --route 1:2 \
    --route 2:0 \
    --route 2:1

In terminal 0

picocom 0

In terminal 1

picocom 1

In terminal 2

picocom 2

Characters entered in terminal 0 will be sent to terminal 2 only. Characters entered in terminal 1 will be sent to terminal 2 only. Characters entered in terminal 2 will be sent to both terminals 0 and 1.

Comparison to TTYBUS

vsp-router is similar to TTYBUS.

The key differences is in how data is written. TTYBUS broadcasts data to all ports. vsp-router routes data to select ports.

The following 3-port configurations are the equivalent.

TTYBUS

tty_bus -d -s bus
tty_fake -d -s bus 0
tty_fake -d -s bus 1
tty_fake -d -s bus 2

vsp-router

vsp-router \
    --create 0 \
    --create 1 \
    --create 2 \
    --route 0:1 \
    --route 0:2 \
    --route 1:0 \
    --route 1:2 \
    --route 2:0 \
    --route 2:1

Comparison to socat

Socat establishes a bidirectional channel between two end points. Vsp-router establishes a multi-directional channel between N end points. Socat supports several different types of end points. Vsp-router supports two: virtual serial ports and physical serial ports.

Vsp-router could be combined with socat to enable interesting use cases. For example, vsp-router could be used to snoop a physical serial port and paired with socat to send the snooped data over UDP.

License

Licensed under either of

• Apache License, Version 2.0 (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
• MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)

at your option.

Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.