sylvac-measure 0.2.1

Python package for Sylvac Bluetooth measurement instruments

sylvac-python

Python package for reading measurements from Sylvac Bluetooth Low Energy measurement instruments (calipers, gauges, micrometers, …).

Communication uses the Sylvac SDS (Simple Data Service) and SMS (Sylvac Metrology Service) GATT profiles over BLE via bleak, based on the official Sylvac Bluetooth developer tools. SDS provides real-time measurement notifications, while SMS allows querying and configuring instrument settings via ASCII commands.

Tested devices

Sylvac's Bluetooth interface is largely consistent across their product range, so this library should work with most BLE-enabled Sylvac instruments. The following devices have been confirmed to work:

Device	Product page
Sylvac S_Cal EVO	discontinued

(Please create a GitHub issue to report more tested devices.)

Requirements

• Python 3.11+
• A Sylvac BLE instrument advertising in SIMPLE profile (the factory default — no pairing required)

Installation

pip install sylvac-measure

Or from source:

git clone https://codeberg.org/stv0g/sylvac-python
cd sylvac-python
pip install -e .

Quick start

Command-line

The sylvac command provides several subcommands for interacting with Sylvac BLE instruments.

Scanning for devices

# List all available Sylvac BLE devices
sylvac list

# Scan for longer duration
sylvac list --timeout 20

# Filter by device name prefix (default: "SY")
sylvac list --prefix SY

Output:

726B9552-D5B0-4BE6-C974-C8BCA6C2F2C9 SY295

Device information

# Show device identification and status (default command)
sylvac info

# Connect to a specific device by address
sylvac info --address AA:BB:CC:DD:EE:FF

# Output as JSON
sylvac info --json

# Verbose BLE debug output
sylvac info --log-level DEBUG

Taking measurements

# Take a single measurement
sylvac measure

# Stream measurements continuously (Ctrl-C to stop)
sylvac measure --follow

# Capture measurements via data button press
sylvac measure --button

# Output measurements as JSON
sylvac measure --json

# Omit the unit from output
sylvac measure --value-only

# Stream measurements from a specific device
sylvac measure --address AA:BB:CC:DD:EE:FF --follow

Output (one measurement per line on stdout):

20.58 mm
20.59 mm
20.58 mm  [max]

Reading configuration

# Show all configuration settings
sylvac config get

# Show a specific setting
sylvac config get unit
sylvac config get resolution
sylvac config get preset
sylvac config get display
sylvac config get eco
sylvac config get keyboard-locked
sylvac config get last-calibration
sylvac config get next-calibration
sylvac config get id
sylvac config get number
sylvac config get favorites
sylvac config get standby-timeout
sylvac config get output

Writing configuration

# Set the display unit
sylvac config set unit mm
sylvac config set unit in

# Lock or unlock unit changes
sylvac config set unit-locked true
sylvac config set unit-locked false

# Lock or unlock keyboard
sylvac config set keyboard-locked true
sylvac config set keyboard-locked false

# Set a preset value
sylvac config set preset 10.5

# Freeze or unfreeze the display
sylvac config set display frozen
sylvac config set display live

# Set calibration dates (YYYY-MM-DD format)
sylvac config set last-calibration 2026-01-15
sylvac config set next-calibration 2027-01-15

# Enable or disable economy mode
sylvac config set eco true
sylvac config set eco false

# Set instrument number
sylvac config set number "MY-INSTRUMENT"

# Set standby timeout (minutes)
sylvac config set standby-timeout 30

# Enable or disable continuous data output
sylvac config set output true
sylvac config set output false

Device control

# Put the instrument into sleep mode
sylvac poweroff

# Put the instrument into standby mode
sylvac standby

# Reset instrument user settings
sylvac reset

Connection options

All commands support the following connection options:

# Specify device address (skips scanning)
sylvac <command> --address AA:BB:CC:DD:EE:FF

# Set scan timeout when address is not specified (default: 10s)
sylvac <command> --timeout 20

Python API

import asyncio
import sylvac

async def main():
    device = await sylvac.scan(timeout=10)
    if device is None:
        print("No device found")
        return

    async with sylvac.Device(device.address) as dev:
        async for m in dev.measurements():
            print(f"{m.format()}  (mode: {m.mode})")

asyncio.run(main())

Scan for all visible instruments

from sylvac import scan_all

async for d in scan_all(timeout=10):
    print(d.name, d.address)

Send instrument commands

async with sylvac.Device(address) as dev:
    await dev.send_command("SVR1")   # Enable saver mode (notify on change only)
    await dev.send_command("UNI?")   # Query current unit

Read battery information

async with sylvac.Device(address) as dev:
    # Get battery state via SMS command (OK or LOW)
    battery_state = await dev.get_battery_state()
    print(f"Battery state: {battery_state}")  # OK or low

    # Get battery level via BLE Battery Service (percentage)
    battery_level = await dev.get_battery_level()
    if battery_level is not None:
        print(f"Battery level: {battery_level}%")

Capture measurements with the data button

async with sylvac.Device(address) as dev:
    # Listen for data button press events
    # This yields a measurement each time the user presses the physical
    # data button on the instrument
    async for measurement in dev.button_measurements():
        print(f"Captured: {measurement.format()}")

Measurement dataclass

Field	Type	Description
value	float	Measurement in unit
unit	Unit	MM, INCH, DEG, RAD, …
resolution	float | None	Smallest increment (same unit), e.g. 0.01
mode	MeasuringMode	NORMAL, MIN, MAX, DELTA
manual	bool	Measurement was taken manually by pressing the DATA button

Measurement.format() returns a numeric string rounded to the instrument's resolution, e.g. "20.58".

Protocol notes

Sylvac instruments expose two relevant GATT characteristics inside the SDS service (0x5000, standard BLE base UUID):

Characteristic	UUID	Description
Measurement	0x5020	Notify — signed 32-bit LE integer, SI-scaled
Parameters	0x5021	Notify — unit, resolution, and mode bitmap

Sylvac instruments also expose the standard Battery Service (0x180F):

Characteristic	UUID	Description
Battery Level	0x2A19	Read/Notify — uint8 percentage (0-100)

Additionally, the SMS (Sylvac Metrology Service) provides:

Characteristic	UUID	Description
DataSend	0x5010	Indicate — triggered when data button is pressed
RemoteRequest	0x5012	Write — send ASCII commands to the instrument
RemoteResponse	0x5013	Notify — receive ASCII responses from instrument

Polling the Measurement characteristic returns a sentinel value (0x7FFFFFFF); notifications must be enabled to receive valid data.

The instrument must be in SIMPLE Bluetooth profile (no pairing/encryption). This is the factory default. If the instrument has been switched to PAIR or HID profile, restore it via:

CFG BT SIMPLE   (sent as ASCII to SMS RemoteRequest characteristic 0x5012)

or use the factory reset: FAC RST.

Sylvac Metrology Service Commands

Command	Description
ID?	Transmits instrument identification (SY276)
BAT?	Transmits battery status (BAT1=ok or BAT0=low)
VER?	Transmit program version and date (Vx.x DD.MM.YYYY)
UNI?	Transmit unit of measure (IN or MM)
UNI0 / UNI1	Lock / unlock unit change function
MM	Activates mm unit
IN	Activates Inch unit
KEY?	Transmits keyboard status (KEY0 or KEY1)
KEY0 / KEY1	Disables/enables keypad (except Send Data)
RST	Reset instrument (user settings)
OFF	Instrument sleep mode
SBY	Instrument stand-by (SIS)
SBY XX	xx number of minutes before stand-by
ECO?	Current economy mode
ECO1 / ECO0	Enables / disables economy mode
RES?	Current resolution mode
RES2 / RES3	Change resolution
LCAL?	Transmit date of last calibration (DD.MM.YYYY)
LCAL JJ.MM.[AA]AA	Enter date of last calibration
NCAL?	Transmit date of next calibration (DD.MM.YYYY)
NCAL JJ.MM.[AA]AA	Enter date of next calibration
NUM?	Transmit instrument number
NUMX..X	Modifies instrument number (10 characters)
OUT0 / OUT1	Disables/enables continuous data output
PRE?	Transmit preset value (±xxx.yyy[yy])
PRE ±XXX.YYYYYY	Enter preset value (max. 199.999mm / 7.83'')
PRE OFF / PRE ON	Activates/deactivates Preset function
?	Transmits displayed value
SET?	Transmit instrument configuration (IN or MM, STO0 or STO1, KEY0 or KEY1, BAT1 or BAT0)
STO?	Transmits display status
STO0 / STO1	Release/freeze display
BT0 / BT1	Disables Bluetooth® module
BTRST	Reset Matching
MAC?	Transmits Bluetooth® module MAC address
FMIN?	Returns FMIN value
FMIN0 / FMIN1	Disable/enable FMIN function
FCT?	Favorites function active?
FCT0…9…A…F	"Favorite" function assignment

Specifications and references

• MEM-PM 292-1806-01 — Bluetooth Profile Specifications
• SPE-PM 292-1744-01 — SDS Specification
• SPE-PM 292-1746-01 — SMS Specification
• S_Mike PRO Instruction Manual
• P12D — Interface description

Credits

Steffen Vogel ([e-mail])

If you find this project useful, consider sponsoring its development on Liberapay.

License

Apache-2.0 — see COPYING.