Mettler Toledo MT-SICS scales#

MTSICSDriver connects to Mettler Toledo scales and weigh modules that implement the MT-SICS serial protocol. It discovers the commands advertised by the connected instrument during setup, so one driver can support multiple models with different command sets.

Property

Value

Protocol

MT-SICS (Mettler Toledo Standard Interface Command Set)

Communication

RS-232 serial

Driver default baud rate

9600

Default USB adapter match

0x0403:0x6001 (FTDI FT232R)

PyLabRobot API

MTSICSDriver

Hardware-validated example

WXS205SDU/15, reported by the instrument as WXS205SDU WXA-Bridge, firmware 1.10

Support is based on the commands reported by the instrument, not on a hard-coded model name. The WXS205SDU/15 is the currently hardware-validated example; other MT-SICS models may expose a different subset of the methods shown below.

Mettler Toledo
MT-SICS scales and weigh modules
WIPv1
scale
weighing
Models
ModelSupport
AB104WIP
AB104-SWIP
AB104-S/FACTWIP
AB135-SWIP
AB135-S/FACTWIP
AB204WIP
AB204-SWIP
AB204-S/FACTWIP
AB265-SWIP
AB265-S/FACTWIP
AB304-SWIP
AB304-S/FACTWIP
AB54WIP
AB54-SWIP
AB54-S/FACTWIP
BBA422WIP
BBA425WIP
BBA432WIP
BBA439WIP
BBA442WIP
BBA462WIP
BBK422WIP
BBK432WIP
BBK442WIP
BBK462WIP
ICS226WIP
ICS241WIP
ICS425WIP
ICS426xWIP
ICS429WIP
ICS435WIP
ICS439WIP
ICS445WIP
ICS449WIP
ICS465WIP
ICS466xWIP
ICS469WIP
ICS629WIP
ICS639WIP
ICS649WIP
ICS669WIP
ICS685WIP
ICS689WIP
IND131WIP
IND221WIP
IND226WIP
IND226xWIP
IND231WIP
IND236WIP
IND246WIP
IND256xWIP
IND331WIP
IND360WIP
IND400WIP
IND425WIP
IND435WIP
IND445WIP
IND465WIP
IND560WIP
IND560xWIP
IND570WIP
IND690WIP
IND780WIP
IND930WIP
IND930SQCWIP
IND970-15WIP
IND970-19WIP
JE1002GWIP
JE1002GEWIP
JE1103CWIP
JE1103CEWIP
JE155DUGWIP
JE2002GWIP
JE2002GEWIP
JE203GWIP
JE203GEWIP
JE3002GWIP
JE3002GEWIP
JE303GWIP
JE303GEWIP
JE4002GWIP
JE4002GEWIP
JE5002GWIP
JE5002GEWIP
JE503CWIP
JE503CEWIP
JE503GWIP
JE503GEWIP
JE703CWIP
JE703CEWIP
JET1002GWIP
JET1002G/AEDWIP
JET1003GWIP
JET1103CWIP
JET12002GWIP
JET1603CWIP
JET2001G/AEDWIP
JET2002GWIP
JET3001G/AEDWIP
JET3002GWIP
JET303GWIP
JET4002GWIP
JET503CWIP
JET6001GWIP
JET6001G/AEDWIP
JET6002GWIP
JET602G/AEDWIP
JET603GWIP
JET703CWIP
JL1502GEWIP
JL6001GEWIP
JL602GEWIP
JP105DUGWIP
JP1203CWIP
JP1603CWIP
JP2002GWIP
JP3002GWIP
JP303GWIP
JP4002GWIP
JP503CWIP
JP503GWIP
JP6002GWIP
JP703CWIP
JP8001GWIP
JP802GWIP
JS1203CWIP
JS1603CWIP
JS2002GWIP
JS3002GWIP
JS303GWIP
JS4002GWIP
JS503CWIP
JS503GWIP
JS6002GWIP
JS703CWIP
JS8001GWIP
JS802GWIP
LA104WIP
LA104EWIP
LA2002WIP
LA2002EWIP
LA203WIP
LA203EWIP
LA204WIP
LA204EWIP
LA4002WIP
LA4002EWIP
LA403WIP
LA403EWIP
LA84WIP
LA84EWIP
MA1002WIP
MA1002EWIP
MA103WIP
MA103EWIP
MA104WIP
MA104EWIP
MA12001LWIP
MA155DUWIP
MA16001LWIP
MA2002WIP
MA2002EWIP
MA2002PWIP
MA2002PEWIP
MA203WIP
MA203EWIP
MA204WIP
MA204EWIP
MA3002WIP
MA3002EWIP
MA303WIP
MA303EWIP
MA32000LWIP
MA32001LWIP
MA4002WIP
MA4002EWIP
MA5001WIP
MA5001EWIP
MA503WIP
MA503EWIP
MA54WIP
MA54EWIP
MA55WIP
MA6001PWIP
MA6001PEWIP
MA6002WIP
MA6002EWIP
MA602WIP
MA602EWIP
MA602PWIP
MA602PEWIP
MA95WIP
ME1002WIP
ME1002EWIP
ME1002T/00WIP
ME1002TE/00WIP
ME103WIP
ME103EWIP
ME103T/00WIP
ME103TE/00WIP
ME2002WIP
ME2002EWIP
ME2002T/00WIP
ME2002TE/00WIP
ME203WIP
ME203EWIP
ME203T/00WIP
ME203TE/00WIP
ME3002WIP
ME3002EWIP
ME3002T/00WIP
ME3002TE/00WIP
ME303WIP
ME303EWIP
ME303T/00WIP
ME303TE/00WIP
ME4001T/00WIP
ME4001TE/00WIP
ME4002WIP
ME4002EWIP
ME4002T/00WIP
ME4002TE/00WIP
ME403WIP
ME403EWIP
ME403T/00WIP
ME403TE/00WIP
ME5002T/00WIP
ME5002TE/00WIP
ME503T/00WIP
ME503TE/00WIP
ME6002T/00WIP
ME6002TE/00WIP
ME603T/00WIP
ME603TE/00WIP
ML1602T/00WIP
ML203T/00WIP
ML3001T/00WIP
ML3002T/00WIP
ML303T/00WIP
ML4002T/00WIP
ML503T/00WIP
ML6001T/00WIP
ML6002T/00WIP
ML802T/00WIP
MR1002WIP
MR104WIP
MR2002WIP
MR203WIP
MR204WIP
MR3002WIP
MR303WIP
MR304WIP
MR4002WIP
MR503WIP
MR6001WIP
MR6002WIP
MR603WIP
MS1003SWIP
MS1003TSWIP
MS1003TS/00WIP
MS104SWIP
MS104TSWIP
MS105WIP
MS105DUWIP
MS12001LWIP
MS12002TSWIP
MS12002TS/00WIP
MS15KLEWIP
MS15KLIPEWIP
MS16001LWIP
MS16001LEWIP
MS1602SWIP
MS1602SEWIP
MS1602TSWIP
MS1602TS/00WIP
MS204WIP
MS204SWIP
MS204TSWIP
MS205DUWIP
MS24KLIPEWIP
MS3001SWIP
MS3002SWIP
MS3002SEWIP
MS3002TSWIP
MS3002TS/00WIP
MS303SWIP
MS303SEWIP
MS303TSWIP
MS303TS/00WIP
MS304SWIP
MS304TSWIP
MS30KLEWIP
MS32000LWIP
MS32000LEWIP
MS32001LWIP
MS32001LEWIP
MS4002SWIP
MS4002SDRWIP
MS4002TSWIP
MS4002TS/00WIP
MS4002TSDRWIP
MS4002TSDR/00WIP
MS403SWIP
MS403TSWIP
MS403TS/00WIP
MS6001SWIP
MS6002SWIP
MS6002SDRWIP
MS6002TSWIP
MS6002TS/00WIP
MS6002TSDRWIP
MS6002TSDR/00WIP
MS603SWIP
MS603TSWIP
MS603TS/00WIP
MS8000SWIP
MS8000SEWIP
MS8001SWIP
MS8001SEWIP
MS8001TSWIP
MS8001TS/00WIP
MS802SWIP
MX104WIP
MX105WIP
MX105DUWIP
MX12001LWIP
MX12002WIP
MX1203WIP
MX1203NWIP
MX16001LWIP
MX2002WIP
MX204WIP
MX205DUWIP
MX303WIP
MX303NWIP
MX304WIP
MX32000LWIP
MX32001LWIP
MX4002WIP
MX6001WIP
MX6002WIP
MX6002DRWIP
MX603WIP
MX603NWIP
PB1501-LWIP
PB1501-SWIP
PB1501-S/FACTWIP
PB1502-LWIP
PB1502-SWIP
PB1502-S/FACTWIP
PB153-LWIP
PB153-SWIP
PB153-S/FACTWIP
PB3001-LWIP
PB3001-SWIP
PB3001-S/FACTWIP
PB3002-LWIP
PB3002-LDRWIP
PB3002-SWIP
PB3002-S/FACTWIP
PB3002-SDRWIP
PB3002-SDR/FACTWIP
PB303-LWIP
PB303-LDRWIP
PB303-SWIP
PB303-S/FACTWIP
PB303-SDRWIP
PB303-SDR/FACTWIP
PB4002-SWIP
PB4002-S/FACTWIP
PB403-SWIP
PB403-S/FACTWIP
PB5001-LWIP
PB5001-SWIP
PB5001-S/FACTWIP
PB503-SWIP
PB503-S/FACTWIP
PB602-LWIP
PB602-SWIP
PB602-S/FACTWIP
PB8000-LWIP
PB8000-SWIP
PB8000-S/FACTWIP
PB8001-LWIP
PB8001-SWIP
PB8001-S/FACTWIP
PG1003-SWIP
PG2002-SWIP
PG203-SWIP
PG3001-SWIP
PG4002-SWIP
PG403-SWIP
PG5002-SWIP
PG503-SWIP
PG6002-SWIP
PG603-SWIP
PG802-SWIP
PR10003MCWIP
PR1200WIP
PR1203WIP
PR2002WIP
PR2003DRWIP
PR2003MCWIP
PR2004MCWIP
PR203WIP
PR3001WIP
PR5001WIP
PR5002WIP
PR5002DRWIP
PR5003DUWIP
PR5003MCWIP
PR502WIP
PR503WIP
PR503DRWIP
PR504DRWIP
PR700WIP
PR8000WIP
PR8001WIP
PR8002WIP
PR8002DRWIP
PR802WIP
PR803WIP
SAG203FWIP
SAG204WIP
SAG245WIP
SAG285WIP
SB12001WIP
SB16000WIP
SB16001WIP
SB16001DRWIP
SB24001DRWIP
SB32000WIP
SB32001DRWIP
SB8000WIP
SB8001WIP
SLF615WIP
SLF630WIP
SLF660WIP
SPCWIP
SPD12002WIP
SPD12002-CWIP
SPE2003-CWIP
SPE4002-CWIP
SPE403-CWIP
SPE404-CWIP
SPE7002-CWIP
SR16000WIP
SR16001WIP
SR16001DRWIP
SR32000WIP
SR32001WIP
SR32001DRWIP
SR64000WIP
SR64001WIP
SR64001DRWIP
SR8001WIP
Viper EXWIP
Viper SCWIP
Viper SWWIP
WKC204CWIP
WKC6002CWIP
WKC603CWIP
WM123WIP
WM124WIP
WM3002WIP
WM3002XWIP
WM503WIP
WM6002WIP
WM6002XWIP
WMC15-SHWIP
WMC24-SHWIP
WMC25-SHWIP
WMF204C-L/IEWIP
WMF204C-L/PNWIP
WMF204C-W/IEWIP
WMF204C-W/PNWIP
WMF303C-L/IEWIP
WMF303C-L/PNWIP
WMF303C-W/IEWIP
WMF303C-W/PNWIP
WMS104CWIP
WMS1203CWIP
WMS204WIP
WMS4002WIP
WMS403WIP
WMS404CWIP
WMS404C-LWIP
WMS6002CWIP
WMS803WIP
WXS204WIP
WXS204S/15WIP
WXS204SV/15WIP
WXS205WIP
WXS205DUWIP
WXS205S/15WIP
WXS205SDU/15Full
WXS205SDUV/15WIP
WXS205SV/15WIP
WXS26WIP
WXS26DUWIP
WXS26S/15WIP
WXS26SDU/15WIP
WXS26SDUV/15WIP
WXS26SV/15WIP
WXSS204WIP
WXSS204/AWIP
WXSS204/MWIP
WXSS204VWIP
WXSS205WIP
WXSS205/AWIP
WXSS205/MWIP
WXSS205DUWIP
WXSS205DU/AWIP
WXSS205DU/MWIP
WXSS205DUVWIP
WXSS205VWIP
WXSS26WIP
WXSS26/AWIP
WXSS26/MWIP
WXSS26DUWIP
WXSS26DU/AWIP
WXSS26DU/MWIP
WXSS26DUVWIP
WXSS26VWIP
WXTP204WIP
WXTP204VWIP
WXTP205WIP
WXTP205DUWIP
WXTP205DUVWIP
WXTP205VWIP
WXTP26WIP
WXTP26DUWIP
WXTP26DUVWIP
WXTP26VWIP
WXTS204WIP
WXTS204/AWIP
WXTS204/MWIP
WXTS204VWIP
WXTS205WIP
WXTS205/AWIP
WXTS205/MWIP
WXTS205DUWIP
WXTS205DU/AWIP
WXTS205DU/MWIP
WXTS205DUVWIP
WXTS205VWIP
WXTS26WIP
WXTS26/AWIP
WXTS26/MWIP
WXTS26DUWIP
WXTS26DU/AWIP
WXTS26DU/MWIP
WXTS26DUVWIP
WXTS26VWIP
WXTS3DUWIP
WXTS3DU/AWIP
WXTS3DU/MWIP
XA105WIP
XA1502SWIP
XA204WIP
XA3001SWIP
XA3002SWIP
XA303SWIP
XA5002SWIP
XA503SWIP
XP105WIP
XP1202SWIP
XP1203SWIP
XP2001SWIP
XP2002SWIP
XP2003SWIP
XP203SWIP
XP204SWIP
XP205WIP
XP26WIP
XP2UWIP
XP4001SWIP
XP4002SWIP
XP404SWIP
XP5003SWIP
XP504WIP
XP56WIP
XP6WIP
XP6001SWIP
XP6002SWIP
XP603SWIP
XP8001SWIP
XP8002SWIP
XP802SWIP
XPE10001LWIP
XPE10001SWIP
XPE10002SWIP
XPE105WIP
XPE1202SWIP
XPE1203SWIP
XPE15002LWIP
XPE16001LWIP
XPE20002LDRWIP
XPE2002SWIP
XPE204WIP
XPE204SWIP
XPE205WIP
XPE205CDRWIP
XPE205DRWIP
XPE26WIP
XPE26CWIP
XPE26DRWIP
XPE3003SWIP
XPE3003SD5WIP
XPE303SWIP
XPE303SNWIP
XPE32000LWIP
XPE32001LWIP
XPE4001SWIP
XPE4002SWIP
XPE404SWIP
XPE5003SWIP
XPE504WIP
XPE505CWIP
XPE56CWIP
XPE6001SWIP
XPE6002SWIP
XPE6002SDRWIP
XPE6003SD5WIP
XPE603SWIP
XPE603SDRWIP
XPE603SNWIP
XPE603SNDRWIP
XPE64000LWIP
XPE64001LWIP
XPE8001SWIP
XPE8002SWIP
XPR10WIP
XPR10003SCWIP
XPR1004SCWIP
XPR105WIP
XPR105DUHRWIP
XPR106DUHWIP
XPR106DUHRWIP
XPR12001LWIP
XPR12001SWIP
XPR12002SWIP
XPR12003SD5WIP
XPR1202SWIP
XPR1203SWIP
XPR15002LWIP
XPR16001LWIP
XPR2WIP
XPR20002LDRWIP
XPR2002SWIP
XPR2003SWIP
XPR2003SCWIP
XPR2004SCWIP
XPR204WIP
XPR204EWIP
XPR204E/AWIP
XPR204E/MWIP
XPR204SWIP
XPR205WIP
XPR225DRWIP
XPR226CDRWIP
XPR226DRWIP
XPR26003LCWIP
XPR2UWIP
XPR2U/AWIP
XPR2U/MWIP
XPR3003SWIP
XPR3004SD5WIP
XPR303SWIP
XPR303SNWIP
XPR305DRWIP
XPR32000LWIP
XPR32001LWIP
XPR32003LD5CWIP
XPR36WIP
XPR36CWIP
XPR36DRWIP
XPR4001SWIP
XPR4002SWIP
XPR404SWIP
XPR5003SWIP
XPR5003SCWIP
XPR5004SCWIP
XPR504SWIP
XPR56WIP
XPR56CWIP
XPR56DRWIP
XPR6002SWIP
XPR6002SDRWIP
XPR6003SD5WIP
XPR603SWIP
XPR603SNWIP
XPR64000LWIP
XPR64001LWIP
XPR64002LCWIP
XPR64002LC-TWIP
XPR64003LD5CWIP
XPR6UWIP
XPR6U/MWIP
XPR6UD5WIP
XPR8001SWIP
XPR8002SWIP
XS10000MWIP
XS10001LWIP
XS10001MWIP
XS10001SWIP
XS10002SWIP
XS1003SWIP
XS104WIP
XS105WIP
XS1202SWIP
XS1203SWIP
XS16000LWIP
XS16000MWIP
XS16001LWIP
XS2002SWIP
XS203SWIP
XS204WIP
XS204SXWIP
XS205WIP
XS3WIP
XS303SWIP
XS303SNWIP
XS32000LWIP
XS32001LWIP
XS32001LDRWIP
XS32001LXWIP
XS4001SWIP
XS4002SWIP
XS403SWIP
XS5003SWIP
XS5003SXDRWIP
XS6001MWIP
XS6001MDRWIP
XS6001SWIP
XS6002SWIP
XS6002SDRWIP
XS6002SXWIP
XS603SWIP
XS603SNWIP
XS603SXWIP
XS64WIP
XS64001LXWIP
XS8001LWIP
XS8001SWIP
XS802SWIP
XSR10001LWIP
XSR10001SWIP
XSR10002SWIP
XSR104WIP
XSR105WIP
XSR105DUWIP
XSR1202SWIP
XSR1203SWIP
XSR16000LWIP
XSR16001LWIP
XSR2002SWIP
XSR204WIP
XSR204DRWIP
XSR205DUWIP
XSR225DUWIP
XSR303SWIP
XSR303SNWIP
XSR304WIP
XSR32000LWIP
XSR32001LWIP
XSR32001LDRWIP
XSR4001SWIP
XSR4002SWIP
XSR6001SWIP
XSR6002SWIP
XSR6002SDRWIP
XSR603SWIP
XSR603SNWIP
XSR64WIP
XSR8001SWIP
APIpylabrobot.mettler_toledo.MTSICSDriver
Manager@rickwierenga
NotesThe listed models are known to support SICS; only WXS205SDU/15 has been hardware-validated with this driver (WXA-Bridge firmware 1.10).
code

How it communicates#

MT-SICS (Mettler Toledo Standard Interface Command Set) is an ASCII request/response protocol. Commands and responses are terminated by carriage return and line feed. The driver communicates through PyLabRobot’s serial transport and handles framing, response parsing, multi-line responses, and MT-SICS error codes.

During setup(), the driver resets the interface, queries I0 to discover supported commands, reads the device identity and firmware, and selects grams as the host unit when the instrument supports that setting. A method whose MT-SICS command is unavailable on the connected model raises MettlerToledoError before sending it.

Physical setup#

Hardware layouts and connectors vary by model. Some systems use a separate load cell, electronic unit, and terminal, while others integrate these components. Follow the manual for your instrument, then connect its MT-SICS-capable RS-232 interface to the computer. A USB-to-serial adapter is normally required.

The driver defaults to the FTDI FT232R VID:PID 0x0403:0x6001. If your adapter uses different identifiers, pass the serial port explicitly or provide its vid and pid when creating the driver.

Install PyLabRobot with serial support before continuing:

pip install "pylabrobot[serial]"

Warning

Place the scale on a stable, level surface and follow the warm-up and environmental guidance for your model before measuring. An instrument that is not ready may report that a command is understood but not currently executable.

Connect#

Create the driver with the serial port used by the scale and call setup(). Port names are typically /dev/ttyUSB0 on Linux, /dev/cu.usbserial-* on macOS, and COM3 or similar on Windows. If port is omitted, the driver searches for the configured USB VID and PID.

from pylabrobot.mettler_toledo import MTSICSDriver

scale = MTSICSDriver(port="/dev/cu.usbserial-110")  # replace with your serial port
await scale.setup()

Confirm the discovered instrument#

setup() records the identity and capacity reported by the instrument. Inspect these values before starting a measurement workflow, especially when several serial devices are connected.

print(f"Model: {scale.device_type}")
print(f"Serial number: {scale.serial_number}")
print(f"Firmware: {scale.firmware_version}")
print(f"Capacity: {scale.capacity} g")

Zero the empty scale#

Remove everything from the weighing platform, then call zero(). The default waits for a stable reading. Use zero(timeout=0) only when an immediate zero is preferable to waiting for stability.

await scale.zero()

Tare a container#

Place the empty container on the platform and wait for the reading to settle. tare() stores its weight so subsequent readings report only the sample’s net weight.

await scale.tare()

Read a stable weight#

Add the sample to the tared container. read_weight() waits for stability and returns the weight in grams as a float.

weight_g = await scale.read_weight()
print(f"Weight: {weight_g:.4f} g")

Read immediately#

Use timeout=0 when the current value is needed even if it is still changing. The result is still expressed in grams.

current_weight_g = await scale.read_weight(timeout=0)
print(f"Current weight: {current_weight_g:.4f} g")

Inspect the stored tare#

Query the tare value currently stored by the scale.

tare_weight_g = await scale.request_tare_weight()
print(f"Stored tare: {tare_weight_g:.4f} g")

Clear the tare#

Remove the container, then clear the stored tare when the workflow is finished.

await scale.clear_tare()

Measure the internal temperature#

Some MT-SICS instruments, including the hardware-validated WXS205SDU/15, expose an internal temperature sensor with the M28 command. This can be useful when temperature affects density calculations in gravimetric verification. Skip this call if your model does not advertise M28; the driver will otherwise raise MettlerToledoError.

temperature_c = await scale.measure_temperature()
print(f"Internal temperature: {temperature_c:.1f} °C")

Query device identity#

Identity methods can be called again after setup when a workflow needs to record instrument provenance alongside its measurements. The additional identity fields below are model dependent; an unsupported command raises MettlerToledoError.

identity = {
  "serial_number": await scale.request_serial_number(),
  "device_type": await scale.request_device_type(),
  "model": await scale.request_model_designation(),
  "firmware": await scale.request_firmware_version(),
  "software_material_number": await scale.request_software_material_number(),
}
identity

Query device status#

The following read-only calls report the instrument’s clock, uptime, and next configured service date when their corresponding commands are supported by the connected model.

status = {
  "date": await scale.request_date(),
  "time": await scale.request_time(),
  "uptime_minutes": await scale.request_uptime_minutes(),
  "next_service_date": await scale.request_next_service_date(),
}
status

Read weight with MT-SICS status#

request_net_weight_with_status() exposes the structured MT-SICS response when a workflow needs the stability state, unit code, readability, approval state, or tare information in addition to the numeric weight.

response = await scale.request_net_weight_with_status()
print(f"Command: {response.command}")
print(f"Status: {response.status}")
print(f"Data: {response.data}")

Read a multi-line response#

Some MT-SICS commands return several lines. The driver returns them as a list of MettlerToledoResponse objects. For example, instruments that implement I14 can report installed components through device-information category 0.

device_info = await scale.request_device_info(category=0)
for line in device_info:
  print(line.command, line.status, line.data)

Inspect weighing configuration#

These configuration-query methods are read-only and model dependent. Their returned values are MT-SICS setting codes; consult the Mettler Toledo MT-SICS reference for the meaning of each code on your model.

configuration = {
  "weighing_mode": await scale.request_weighing_mode(),
  "environment_condition": await scale.request_environment_condition(),
  "auto_zero": await scale.request_auto_zero(),
  "update_rate_hz": await scale.request_update_rate(),
}
configuration

Command availability across models#

Not every MT-SICS instrument implements every command. During setup(), the driver queries I0 and records the commands advertised by the connected instrument. Calling a method whose command was not advertised raises MettlerToledoError before anything is sent.

For example, the WXS205SDU/15 WXA-Bridge used for hardware validation does not expose the timed zero/tare/read commands, display commands, the cancel-all command, or remaining-range query. Those methods remain available for other MT-SICS models that advertise the corresponding commands.

Methods such as set_device_id(), set_date(), and set_time() intentionally change persistent device state and are therefore not run in this hello-world guide.

Disconnect#

Always stop the driver when the workflow finishes. stop() attempts to reset the interface to a determined state before closing the serial connection.

await scale.stop()