testing z3scn python module

[zappadoc]

Hi,
Here is a demo script of the z3scn python module that manage the SCN5 and SCN6 electric linear actuators. This script contains a very useful functions z3setup() to enter easily the init(...) parameters, see the API doc for more info on my dev.blog zappadoc.com website.
This assumes that your actuator is configured on COM4 with a stroke of 100mm, change the init parameters if needed.

Code: Python

import z3scn as dev
import time
import math

def z3setup(**kwargs) -> list[int]:
    """
    Prepare ordered and validated actuator initialization parameters.

    Parameters (all optional except 'com'):
        com (int): Required. COM port number (e.g., 3 for COM4).
        id (int): Device ID (default 0).
        stroke (int): Stroke length (default 100, only 50, 150, or 200 are valid; others become 100).
        accel (int): Acceleration value (default 200).
        gain (int): Control gain (default 7).
        normalSpd (int): Normal movement speed (default 7800).
        homeSpd (int): Homing speed (default 2000).
        moveMode (int): Movement mode (default 0).
        gohome (int): Whether to go home on init (default 0).
        gocenter (int): Whether to go center after home (default 0).
        diag (int): Diagnostic flag (default 0).

    Returns:
        list[int]: A list of parameters ready to be unpacked into the init() function.

    Raises:
        ValueError: If 'com' is missing or unknown parameters are passed.

    Example:
        params = z3setup(com=4, accel=385)
        dev.init(*params)
    """
    param_order = ["com", "id", "stroke", "accel", "gain", "normalSpd", "homeSpd", "moveMode", "gohome", "gocenter", "diag"]
    defaults = {
        "id": 0, "stroke": 100, "accel": 200, "gain": 7,
        "normalSpd": 7800, "homeSpd": 2000, "moveMode": 0,
        "gohome": 0, "gocenter": 0, "diag": 0
    }
    stroke_valid = {50, 150, 200}

    allowed_keys = set(param_order)
    for key in kwargs:
        if key not in allowed_keys:
            raise ValueError(f"Unknown parameter '{key}'. Allowed parameters are: {', '.join(param_order)}")

    if "com" not in kwargs:
        raise ValueError("Parameter 'com' is required")

    stroke = kwargs.get("stroke", 100)
    kwargs["stroke"] = stroke if stroke in stroke_valid else 100

    args = [kwargs.get(k, defaults.get(k)) for k in param_order]

    while len(args) > 1 and args[-1] == defaults.get(param_order[len(args)-1]):
        args.pop()

    # print(f"[DEBUG] Prepared args: {args}")
    return args


# smooth filter
def smooth_path(start, end, steps):
    return [round(start + (end - start) * 0.5 * (1 - math.cos(math.pi * i / steps)), 2)
            for i in range(steps + 1)]

def sleep(ms):
    time.sleep(ms / 1000.0)

def frange(start, stop, step):
    while start < stop:
        yield start
        start += step

# init scn with COM Port 4 and default parameters (stroke = 100)
if dev.init(*z3setup(com=4)):
    print("Start Testing...")

    z3vers = dev.get_device_info("version")
    print(f"Version: {z3vers}")

    # SCN actuator 100mm
    max_stroke = 100
    pos_center = max_stroke / 2

    # go home position
    dev.go_home()
    dev.submit_check()
    sleep(100)

    # go center position
    if dev.go_center():
        dev.submit_check()
        sleep(100)
    else:
        print("error center failed!") 

    # Params
    pause_fast = 0.05  # quick pause between small move
    pause_long = 0.1   # long pause 500 ms
    repetitions = 2   # cycles

    # key pos.
    low_rest = 20
    low_min = 20
    low_max = 40

    high_rest = 70
    high_min = 70
    high_max = 90

    for cycle in range(repetitions):
            print(f"\n--- Cycle {cycle+1} ---")

            # 1. start Position
            dev.load_position(low_rest)
            dev.submit_check()
            sleep(100)

            # 2. fast move low position
            for _ in range(5):
                for move in (low_max, low_min):
                    dev.go_position(move)
                    time.sleep(pause_fast)

            # 3. Pause
            dev.load_position(high_rest)
            dev.submit_check()
            sleep(500)

            # 4. fast move high position
            for _ in range(5):
                for move in (high_max, high_min):
                    dev.go_position(move)
                    time.sleep(pause_fast)

            # 5. return and pause
            dev.load_position(low_rest)
            dev.submit_check()
            sleep(500)

    # return to center position
    dev.go_center()
    dev.submit_check()
    sleep(100)

    # notify device extension
    dev.terminate()

    print("Test Done!")
else:
    print("Initialization failed!")