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Host software

Any program that can open a serial port can drive the mock. Run the mock in its own Julia process, read the port path it prints, and point your software at that path.

Standalone mock

julia --project=/path/to/MockSOLO -e 'using MockSOLO; d = MockSOLO.start(); println(portname(d)); flush(stdout); wait(d)'

This prints the port path, for example /dev/ttys004, then serves until the process is killed. The path changes on every start, so read it from stdout rather than hard-coding it. Add timescale = 100 inside start(...) to speed moves up.

pytest / pyserial

import subprocess, serial

proc = subprocess.Popen(
    ["julia", "--project=/path/to/MockSOLO", "-e",
     "using MockSOLO; d = MockSOLO.start(timescale=100); "
     "println(portname(d)); flush(stdout); wait(d)"],
    stdout=subprocess.PIPE, stderr=subprocess.DEVNULL, text=True)
port = proc.stdout.readline().strip()
s = serial.Serial(port, 57600, timeout=5)
s.reset_input_buffer()
s.write(b"c")
# reply is 4 position bytes (LSB first) + CR
pos = int.from_bytes(s.read(5)[:4], "little")   # 10667 µsteps = 1000 µm
s.write(b"x" + (20000).to_bytes(4, "little"))  # move to 20,000 µsteps
assert s.read(1) == b"\r"                       # CR when the move ends
s.close()
proc.terminate()

Wrap the Popen … terminate pair in a session-scoped fixture so Julia's startup time is paid once.

What a host must do

  • Send raw bytes. Commands have no terminator. Multi-byte arguments are least-significant byte first. See Protocol.
  • Read the full reply. c replies with 5 bytes; every other command replies with a single CR (0x0D) when its action completes.
  • Purge input after opening. The mock keeps the port open between host sessions, so replies a previous host never read are still queued. The manual (§4.2 note 3) recommends this purge for the real device too. A purge only drops bytes that have already arrived: if the previous host left a move running, its late CR can still arrive after the purge. To be safe, wait out the longest possible move (full travel takes 16.7 s / timescale) before purging.
  • Leave DTR/RTS alone. A pty has no modem-control lines; see Limitations.
  • Pick a timescale. timescale = 1 is real time (a 5000 µm move takes 1.67 s). For test suites use 100 or more. Inf makes moves instant, but then you cannot observe a move in progress.

LabVIEW and others

Software that opens the port path as a plain serial device at 57600 8N1 should work, unless it is built on libserialport or sets DTR/RTS (see Limitations). Only Julia and pyserial hosts have been tested.