Plesty PCD-M02

A PLESTY device module for the Luna (General Photonics) PCD-M02 polarization controller: four piezo fiber squeezers driven at 0–140 V.

The PCD-M02 has no computer interface of its own. Its digital input — a 17-line TTL bus — is wired to an Arduino running StandardFirmata, and this module drives that bus through plesty-arduino-firmata. You talk to channels and volts; the module turns them into pin writes.

Hardware setup

1. On the PCD-M02, remove jumper JP1000 to enable digital control, and disconnect the analog input (or hold it at 0 V) — both inputs active at once can drive the board into saturation (manual GP-UM-PCD-M02-14, p. 9).

2. Upload StandardFirmata to the Arduino (Arduino IDE: File → Examples → Firmata → StandardFirmata).

3. Wire the PCD-M02's 20-pin digital connector JDD to the Arduino. The module's default wiring is the lab's Arduino Mega:

   JDD pin	Line	Mega pin
   1	RW	22
   2	/CS	23
   3	/RESET	24
   4	A0	29
   5	A1	28
   6–17	DB0–DB11 (DB0 least significant)	32–43
   18, 19	DGND	GND

   A board wired differently passes its own Wiring (see below).

Installation

git clone https://gitlab.com/plesty/hub/devices/luna/plesty-pcd-m02.git
cd plesty-pcd-m02
uv sync

Usage

from plesty.pcd_m02 import Device

with Device(port="auto") as pc:  # or "COM5", "/dev/ttyACM0"
    pc.set_voltage(channel=1, voltage=70.0)  # channels 1–4, 0–140 V
    pc.set_voltages(voltages=[10.0, 20.0, 30.0, 40.0])
    print(pc.get_voltages())  # {'voltages': [9.98, 20.0, 30.02, 40.0]}
    pc.step_voltage(2, -5.0)  # stops at 0 V / 140 V

What to know:

• Connecting resets the outputs to 0 V. The bus cannot be read back, so the module starts from the one state it can be sure of. To restore a saved polarization state, call set_voltages after connecting.
• Voltages are reported, not measured. get_voltage answers the value last set in this session, rounded to the 12-bit word (steps of 34 mV).
• Disconnecting leaves the outputs where they are. The controller holds its voltages while the port is closed; the next connect resets them.

A different wiring:

from plesty.pcd_m02 import Device, Wiring

wiring = Wiring(rw=2, cs=3, reset=4, a0=5, a1=6, data=tuple(range(7, 19)))
with Device(port="COM5", wiring=wiring) as pc:
    ...

port="mock" runs against a simulated Arduino with a simulated PCD-M02 on it; pc.simulator.outputs reads its four output voltages.

Run as TCP server

Copy .env.example to .env and set DEVICE_ADDRESS, then:

uv run python -m plesty.pcd_m02 --tcp-port 5555

Open the control panel

uv sync --extra gui
uv run python -m plesty.pcd_m02 --gui