Lakeshore 240

The Lakeshore 240 is a 4-lead meausrement device used for readout of ROXes and Diodes at 1K and above.

usage: python3 agent.py [-h] [--serial-number SERIAL_NUMBER] [--port PORT]
                        [--mode {idle,init,acq}]
                        [--sampling-frequency SAMPLING_FREQUENCY]

Agent Options

--serial-number

Serial number of your Lakeshore240 device

--port

Path to USB node for the lakeshore

--mode

Possible choices: idle, init, acq

Starting action for the agent.

--sampling-frequency

Sampling frequency for data acquisition

Dependencies

The Lakeshore 240 requires USB drivers to be compiled for your machine. A private repository, ls240_drivers, with the required drivers is available on the Simons Observatory Github. This repository provides some other helpful tools, including a set of udev rules for setting the device address automatically when the 240s are connected to the computer.

Note

The 240 drivers are compiled for the specific kernel you are running at installation. If your kernel is updated the drivers will no longer work. The DKMS module provided by the ls24_drivers repository attempts to solve this problem, but does not currently appear to work. Please report any difficulty with the drivers to Brian.

To install the drivers clone the ls240_drivers repository and run make to build the drivers:

$ git clone https://github.com/simonsobs/ls240-drivers.git
$ make

Update the udev rules file, 50-ls240.rules, adding an entry for your devices’ serial numbers, then run:

$ make install_udev

If your devices were plugged in already you will need to unplug and replug them for the udev rules to properly recognize the devices and set the path and permissions appropriately. Once you complete this step they will be recongized on reboots, and the udev rules will not need to be reinstalled unless you add a new device.

Configuration File Examples

Below are configuration examples for the ocs config file and for running the Agent in a docker container.

OCS Site Config

To configure your Lakeshore 240 for use with OCS you need to add a Lakeshore240Agent block to your ocs configuration file. Here is an example configuration block that will automatically start data acquisition:

{'agent-class': 'Lakeshore240Agent',
 'instance-id': 'LSA22Z2',
 'arguments': [['--serial-number', 'LSA22Z2'],
               ['--mode', 'acq']]},

Each device requires configuration under ‘agent-instances’. See the OCS site configs documentation for more details.

Docker Compose

The Lakeshore 240 Agent can (and probably should) be configured to run in a Docker container. An example configuration is:

ocs-LSA22Z2:
  image: simonsobs/socs:latest
  devices:
    - "/dev/LSA22Z2:/dev/LSA22Z2"
  hostname: nuc-docker
  environment:
    - INSTANCE_ID=LSA22Z2
  volumes:
    - ${OCS_CONFIG_DIR}:/config:ro

The serial number will need to be updated in your configuration. The hostname should also match your configured host in your OCS configuration file. The site-hub and site-http need to point to your crossbar server, as described in the OCS documentation.

Example Clients

Device Configuration

Out of the box, the Lakeshore 240 channels are not enabled or configured to correctly measure thermometers. To enable, you can use the agents.lakeshore240.LS240_agent.LS240_Agent.set_values() Task of the LS240 Agent to configure a particular channel. Below is an example of a client that sets Channel 1 of a 240 to read a diode:

from ocs.matched_client import MatchedClient

ls_client = MatchedClient("LSA22Z2")

diode_params = {
    'sensor': 1,
    'autorange': 1,
    'units': 3,
    'enabled': 1,
}

ls_client.set_values.start(channel=1, name="CHWP_01", **diode_params)
ls_client.set_values.wait()

Agent API

class socs.agents.lakeshore240.agent.LS240_Agent(agent, port='/dev/ttyUSB0', f_sample=2.5)

init_lakeshore(auto_acquire=False)

Task - Perform first time setup of the Lakeshore 240 Module.

Parameters:

auto_acquire (bool, optional) – Starts data acquisition after initialization if True. Defaults to False.

set_values(channel, sensor=None, auto_range=None, range=None, current_reversal=None, units=None, enabled=None, name=None)

Task - Set sensor parameters for a Lakeshore240 Channel.

Parameters:

• channel (int) – Channel number to set. Valid choices are 1-8.

• sensor (int, optional) – Specifies sensor type. See socs.Lakeshore.Lakeshore240.Channel.set_values() for possible types.

• auto_range (int, optional) – Specifies if channel should use autorange. Must be 0 or 1.

• range (int, optional) – Specifies range if auto_range is false. Only settable for NTC RTD. See socs.Lakeshore.Lakeshore240.Channel.set_values() for possible ranges.

• current_reversal (int, optional) – Specifies if input current reversal is on or off. Always 0 if input is a diode.

• units (int, optional) – Specifies preferred units parameter, and sets the units for alarm settings. See socs.Lakeshore.Lakeshore240.Channel.set_values() for possible units.

• enabled (int, optional) – Sets if channel is enabled.

• name (str, optional) – Sets name of channel.

get_values(channel)

Task - Get the set values for a particular channel.

Parameters:

channel (int) – Channel to get the set sensor type, range, auto_range, current_reversal, units, and enabled values for. Valid values for channel are 1-8.

The most recent data collected is stored in session data in the structure:

>>> response.session['data']
{"fields":
    {"sensor": "Diode",
     "range": 1000,
     "auto_range": True,
     "current_reversal": True,
     "unit": "K",
     "enabled": True},
 "timestamp":1601925677.6914878}

upload_cal_curve(channel, filename)

Task - Upload a calibration curve to a channel.

Parameters:

• channel (int) – Channel number, 1-8.

• filename (str) – Filename for calibration curve.

acq(sampling_frequency=2.5)

Process - Start data acquisition.

Parameters:

sampling_frequency (float) – Sampling frequency for data collection. Defaults to 2.5 Hz

The most recent data collected is stored in session data in the structure:

>>> response.session['data']
{"fields":
    {"Channel_1": {"T": 99.26, "V": 99.42},
     "Channel_2": {"T": 99.54, "V": 101.06},
     "Channel_3": {"T": 100.11, "V":100.79},
     "Channel_4": {"T": 98.49, "V": 100.77},
     "Channel_5": {"T": 97.75, "V": 101.45},
     "Channel_6": {"T": 99.58, "V": 101.75},
     "Channel_7": {"T": 98.03, "V": 100.82},
     "Channel_8": {"T": 101.14, "V":101.01}},
    {'connection': {'last_attempt': 1601925677.6914878,
                    'connected': True}}
 "timestamp":1601925677.6914878}

Supporting APIs

class socs.Lakeshore.Lakeshore240.Module(port='/dev/tty.SLAB_USBtoUART', baud=115200, timeout=10)

Allows communication to Lakeshore Module. Contains list of inputs which can be read from.

msg(msg)

Send command or query to module. Return response (within timeout) if message is a query.

class socs.Lakeshore.Lakeshore240.Channel(ls, channel_num)

Object for each channel of the lakeshore module

channel_num

The number of the channel (1-8). This should not be changed once set

Type:

int

name

Specifies name of channel

Type:

str

sensor

1 = Diode, 2 = PlatRTC, 3 = NTC RTD

Type:

int

auto_range

Specifies if channel should use autorange (1,0).

Type:

int

range

Specifies range if auto_range is false (0-8). Range is accoriding to Lakeshore docs.

Type:

int

current_reversal

Specifies if current reversal should be used (0, 1). Should be 0 for diode.

Type:

int

unit

1 = K, 2 = C, 3 = Sensor, 4 = F

Type:

int

enabled

Sets whether channel is enabled. (1,0)

Type:

int

set_values(sensor=None, auto_range=None, range=None, current_reversal=None, unit=None, enabled=None, name=None)

Sets Channel parameters after validation.

Parameters:

• channel (int) – Channel number to set. Valid choices are 1-8.

• sensor (int, optional) –

  Specifies sensor type:

  1	Diode
  2	PlatRTC
  3	NTC RTD

• auto_range (int, optional) – Specifies if channel should use autorange. Must be 0 or 1.

• range (int, optional) –

  Specifies range if auto_range is false. Only settable for NTC RTD:

  0	10 Ohms (1 mA)
  1	30 Ohms (300 uA)
  2	100 Ohms (100 uA)
  3	300 Ohms (30 uA)
  4	1 kOhm (10 uA)
  5	3 kOhms (3 uA)
  6	10 kOhms (1 uA)
  7	30 kOhms (300 nA)
  8	100 kOhms (100 nA)

• current_reversal (int, optional) – Specifies if input current reversal is on or off. Always 0 if input is a diode.

• units (int, optional) –

  Specifies preferred units parameter, and sets the units for alarm settings:

  1	Kelvin
  2	Celsius
  3	Sensor
  4	Fahrenheit

• enabled (int, optional) – Sets if channel is enabled.

• name (str, optional) – Sets name of channel.

get_values()

Returns the values set for this channel.

See set_values for value meanings/interpretations.

get_reading(unit=None)

Get a reading from the channel in the specified units.

If no unit is provided, use the one determined by the channel settings.

Parameters:

unit (str) – Units for reading, options are Kelvin (K), Celcius (C), Fahrenheit (F), or Sensor (S)

load_curve_point(n, x, y)

Loads point n in the curve for specified channel

load_curve(filename)

Upload calibration curve to channel from file.

Parameters:

filename (str) – Calibration file for upload.

delete_curve()

Delete calibration curve from channel.

class socs.Lakeshore.Lakeshore240.Curve(filename=None, header=None, breakpoints=None)

Header for calibration curve:

:Sensor Model:      Name of curve
:Serial Number:        Serial Number
:Data Format:    2 = V:K, 3 = Ohms:K, 4 = log(Ohms):K
:SetPoint Limit:     Temperature Limit (in K)
:Temperature Coefficient:     1 = negative, 2 = positive
:Number of Breakpoints:     Number of curve points