Lake Shore 350 Python Interface

Python interface for reading temperatures from the Lakeshore 350 Temperature Controller.

Installation

Clone this repository and install:

git clone https://github.com/MazinLab/lakeshore350-python
python3 -m venv lakeshore350-env
source lakeshore350-env/bin/activate  
cd lakeshore350-python
pip install -e .

Usage

This repo is intended to be functional through simple command line arguments without running any scripts individually. To see a comprehensive list of command line functionality, execute lakeshore350 --help

Basic Checks

Read all inputs (A-C, D1-D5)

lakeshore350 --all

Get device information:

lakeshore350 --info

Recording Temperatures

Calibrating GL7 Temperatures

The MEC 4K and 50K thermometers are read out in sensor units and calibrated directly on the lakeshore. The GL7 thermometry must be calibrated in software currently.

For example, to request a sensor reading from the 3-head, we use read_sensor from TemperatureReader in temperature.py. Then we import from .head3_calibration import convert_3head_resistance_to_temperature. This function connects to the 3-head calibration .csv file located in \gl7_calibrations. There is a calibration .csv for the 3-head, 4-head, and pumps/switches. There are also python files for creating the calibration for the 3-head, 4-head, and pumps/switches. These python files create linear interpolations based on the data provided in the calibration csv's. They can be called upon by their function, i.e. convert_3head_resistance_to_temperature to quickly convert a sensor measurement to a temperature.

***Note the 4head calibration has a fudge factor currently, needs to be addressed for a more exact measurement.

temperature.py

This is the primary python script that queries temperatures and sensor readings for the lakeshore350. The functionality from temperature.py is implimented in the whole repo. For inputs that directly have temperature outputs (or are calibrated directly on the lakeshore) like the 4K plate, we use the read_temperature function. For outputs that are read in sensor units like the 3-head, 4-head, 3-pump, or 4-pump, we use the read_sensor function.

This script also includes the send_command function which allows us to send serial commands directly to the lakeshore. temperature.py does not convert sensor units to temperature, this is performed within main.py or record_temps.py. It simply defines the functions for querying these sensor readings, or temperature readings, and then the calibrations are handled wherever the temperature is requested like main.py or record_temps.py.

record_temps.py

record_temps.py should be run in a tmux pane whenever the fridge is running. Running this script will automatically create a .csv with the date in the \temps folder. If the folder doesn't exist yet it will create it. If you run record_temps.py multiple times in one day, it will append a number to the end of each .csv to differentiate them.

record_temps.py uses the TemperatureReader class from lakeshore350/temperature.py. It will query the temperatures from the lakeshore every 30 minutes and print them as command line output and in the .csv. Currently, record_temps.py records:

1. date
2. time
3. 4K temperature
4. 50K temperature
5. 3-head resistance and temperature
6. 4-head resistance, adjusted resistanced, and temperature from adjusted resistance
7. 3-pump voltage and temperature
8. 4-pump voltage and temperature

Heaters/Switches (Outputs 1-4)

Basic Command Line Functionality

Heater Output 1 -> 4-pump heater
Heater Output 2 -> 3-pump heater
Analog Output 3 -> 4-pump switch (4-switch)
Analog Output 4 -> 3-pump switch (3-switch)

To query the heater status,

lakeshore350 --outputs-query-all

Returns a list of queries for all outputs

To set output parameters (i.e. max current, mode),

lakeshore350 --outputs-set-params

To set heater range,

lakeshore350 --outputs-set-range

To set output percentage,

lakeshore350 --outputs-set OUTPUT PERCENT

Note, when setting output percentage, query the output parameters through HTRSET or ANALOG first.
This percentage is based on the set max current (which differs from output 1/2) and set max voltage (differs from output 3/4) based on the specified units. Max current output 1 = 0.1A, max current output 2 = 0.33A based on the GL7 300 Ohm resistance.
Setting this value too high can damage the heaters/lakeshore350

Using outputs-query

lakeshore350 --outputs-query-all or lakeshore350 --outputs-query <output number> are the primary means of quering the status of outputs.

The outputs print with the following syntax:

MOUT? prints the manual output percentage (should be 0 if everything is off, or the percent the user set with outputs-set
HTR? is only for outputs 1 and 2. It prints the manual output percentage, should match MOUT.
HTRSET? is only for outputs 1 and 2. It prints the output parameters as <htr resistance>,<max current>,<max user current>,<current/power>
OUTMODE? prints the mode, as <mode>, <input>, <power up enable>. This should print 3,0,0 (open loop mode, no input, power up disabled).
RANGE? prints a number 1-5 of the output range. 5 means we are using 100% of the output range, it should be set to 5. To set output range, execute lakeshore350 --outputs-set-range <output> <range number 1-5>
AOUT? is only for outputs 3 and 4. It prints the manual output percentage, which should match MOUT. It's the analog equivalent of the HTR? command
ANALOG is only for outputs 3 and 4. It prints in the syntax <input>,<units>,<high value>,<low value>,<polarity>. It can be changed with outputs-set-params

Using outputs-set-params

Serial Syntax

Executing lakeshore350 --outputs-set-params will prompt the two following commands. The command line walks the user through the process of setting these commands, this is just some more detail.

All of these serial commands are initialized in outputs.py and called to in main.py.

HTRSET sets the parameters for output 1 and 2 (heaters)
Example Syntax

HTRSET <output>, <resistance>, <max current>, <max user current>, <current/power>

output specifies output 1 or 2
htr resistance 1 = 25 Ohms, 2 = 50 Ohms
max current shows max current (relevant for closed loop/PID) 0 = User Specified, 1 = 0.707 A, 2 = 1 A, 3 = 1.141 A, 4 = 2 A
max user current if max current = 0, this is the current the user has set as the max
current/power specifies what format the output is display in, and what the MOUT percentage determines

Recommended Arguments:
HTRSET 1,2,0,0.1,1
HTRSET 2, 1,0,+1.732,1

*Note Output 1 parameters can vary (variable resistance, variable max current, max power 75W) but Output 2 is fixed and low power (max current 0.1 A, max power 1W). It may not be possible to use HTRSET to change the settings on output 2.

ANALOG sets the parameters for output 3 and 4 (switches)
Example Syntax

ANALOG <output>, <input>,<units>,<high value>, <low value>, <polarity>

output specifies output 3 or 5
input For closed loop/PID specifies which input to monitor 0 = none, 1 = Input A, 2 =Input B, 3 = Input C, 4 = Input D (5 = Input D2, 6 = Input D3, 7 = Input D4, 8 = Input D5 for 3062 option)
units specifies what units to base output voltage on (also for closed loop/PID)
high value when in Monitor Out Mode, specifies data where we reach 100% output. Units are same as those specified in
low value when in Monitor Out Mode, this parameter represents the data where we reach -100% output if in the bipolar, or 0% output if positive only. Units are same as those specified in
polarity Specifies output voltage is 0 = unipolar (positive output only) or 1 = bipolar (positive or negative output)

Reccomended Arguments:
3, 0,1,+5.00000,+0.00000,0
4, 0,1,+5.00000,+0.00000,0

Command Line Usage Examples

1) Let's say I want to set my output 1 to a resistance of 50ohms, user specified 0.1A max current, measured in current units. I execute:

lakeshore350 -outputs-set-params

This returns a prompt: Enter output number (1, 2, 3, or 4):

I enter 1, and then I am prompted for HTRSET args (minus the first arg, for output number).

I enter 2, 0, 0.1, 1.

Now my output 1 parameters are set and I can double check with lakeshore350 --outputs-query 1

2) Let's say I want to set my output 3 to no control input, kelvin units, 5 V max, no min, 0 polarity. I execute:

lakeshore350 -outputs-set-params

This returns a prompt: Enter output number (1, 2, 3, or 4):

I enter 3, and then I am prompted for ANALOG args (minus the first arg, for output number).

I enter 0,1,+5.00000,+0.00000,0.

Now my output 3 parameters are set and I can double check with lakeshore350 --outputs-query 3

Using outputs-set

--outputs-set <output> <percent value> is the primary method of turning on the heaters (outputs 1 and 2) and switches (outputs 3 and 4).

Serial Syntax

MOUT sets the percent output for each output. For the heaters output 1 and 2 this is the percentage of max current (in the current setting) and for the switches output 3 and 4 this the percentage of max voltage (5V). Note that the max current is different for output 1 and 2.

Example Syntax

MOUT <output> <value> 

specifies which output 1, 2, 3, 4
percentage

Command Line Usage Examples

1) Let's say I want to turn on the 3-switch. First I always outputs-query 4 to make sure my max voltage is 5V.

Then I execute:

lakeshore350 --outputs-set 4 100

Now there are 5V going through the 3-switch.

2) Let's say I want to turn on the 4-pump heater. Do not just turn it on to 100%, power up slowly

lakeshore350 --outputs-set 1 10%

This sets output 1 to 10%. Output 1 max current is 0.1A so 10% sends in 10mA, or a voltage of 3V for the 300Ohm resistance heater.

Requirements

• Python 3.7+
• pyserial
• Lake Shore 350 connected via USB serial