Electrometer Developer Guide#

The Electrometer is a standard salobj CSC. It communicates over ethernet, but using a serial-to-ethernet converter. The CSC owns SAL-facing behavior such as events, detailed state transitions, image name allocation, and large file object publication. The controller classes own device-facing behavior such as SCPI command sequencing, controller state, scan readout, and FITS file generation.

Docushare collection

Device Setup#

The electrometer uses an RS-232 serial connection as it’s primary communication method. It is connected to a Moxa Nport 5110 ethernet to serial converter, which is what the CSC connects to.

We use the following serial connection settings:

  • Baud Rate = 57.6 K

  • Flow control = XON/XOFF

  • Terminator = <CR>

  • Parity = None

  • Stop bits = 1

Note

Flow-control settings must match on the electrometer and the Moxa. If an installation is operating over an unreliable wireless bridge, dropped TCP sessions or stale serial flow-control state can leave the device unresponsive until the connection or instrument is reset. In that case, test any change to XON/XOFF conservatively and apply the same flow-control choice on both ends of the serial link.

Electrometer#

Important

The RS-232 serial connection between the electrometer and moxa converter requires a straight-through male/female cable, and not a null modem connection. Cable lengths should be minimized.

The electrometer and photodiode documentation is found on Docushare. The devices must also have their serial/RS-232 communications configured to the proper parameters. Directions on how to do so for the electrometer are found on page X of the user manual. The parameters which must be set are:

  • Baud Rate = 57.6 K

  • Flow control = XON/XOFF

  • Terminator = <CR>

Moxa Serial-to-Ethernet converter#

The moxa Nport 5110 manual is on Docushare.

Setting up these devices for the first time is a bit tricky, follow the steps closely.

  1. Request a DHCP IP reservation from IT corresponding to the MAC address on the back of the device.

  2. Plug in to network and connect to a power source. The moxa device will try to connect to 192.168.127.XX (see address on the back of device). On the office network, nothing will ping the device and therefore it will not report anything back and therefore will not receive an IP automatically and therefore will look like it can’t communicate. This is because there is no device on the same subnet.

  3. From a device on the same network (running linux), add a second IP:

    sudo ip a add 192.168.127.10/24 dev eth0

  4. Then ping the entire subnet.

    ping 192.168.127.254 This will make it such that the moxa device comes online, but with a 192.168.127.254 IP address.

  5. On the same device you used to ping it, open a web browser and navigate to:

    192.168.127.254/main.htm Then login to the web-API and the device settings can be applied.

  6. The basic settings can be left as the defaults, as shown in the following figure, but a name can be added if desired.

    Moxa basic settings

    Adding a name is optional, but recommended.#

  7. The serial settings should be as follows, and as shown in the following figure. - baud 57.6k, data bits 8, stop 1, parity non, FIFO enabled, flow ctrl xon/off, interface rs-232

    Moxa serial settings

    The serial settings must match the electrometer settings.#

Important

Before continuing, make sure to have a reserved IP from IT for the Moxa’s MAC address.

  1. The network settings should be in TCP server mode, with the default settings:

    Moxa Operating settings

    The default mode is not TCP Server, and therefore must be changed on initial setup.#

  2. The network settings should use DHCP, with the following settings:

    Moxa network settings

    When the IP configuration is set to DHCP, and the setting is saved, the device will reset and automatically populate the gateway, netmask and others, also grabbing the assigned IP.#

Once the electrometer is configured, the following code can be used to verify functionality.

import socket
import time
HOST="140.252.147.109"; PORT=4001
s=socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.connect((HOST, PORT))
time.sleep(0.5)
# After the following command, a "REM" will appear on the electrometer LED screen.
s.sendall(f'*idn?\r'.encode())
# Pause here to ensure all data gets written to the buffer
time.sleep(0.5)
data=s.recv(1024*2)
print(f'data is: {data}')

This should return:

b'KEITHLEY INSTRUMENTS INC.,MODEL 6517B,4114292,A13/700x \r'

Dependencies#

Electrometer API#

The content in this section is autogenerated from docstrings.

lsst.ts.electrometer Package#

Functions#

command_csc()

Run the command-line commander for the indexed Electrometer CSC.

execute_csc()

Run the indexed Electrometer CSC.

Classes#

AccessoryConfig(vsource, temperature)

Store accessory configuration flags for the electrometer.

AverFilterType(value[, names, module, ...])

The type of average filters.

ControllerConfig(mode, range, ...)

Store controller configuration derived from the CSC config.

ControllerSettings(mode, range, ...)

Cache controller settings that the CSC publishes as SAL events.

ElectrometerCommandFactory()

Format SCPI commands common to supported electrometers.

ElectrometerController([log])

Provide high-level control for an electrometer.

ElectrometerCsc(index[, config_dir, ...])

Implement the Electrometer CSC.

Error(value[, names, module, qualname, ...])

CSC fault error codes.

Filter(value[, names, module, qualname, ...])

The type of filters

KeithleyElectrometerCommandFactory()

Format Keithley-specific SCPI commands for RS-232 control.

KeithleyElectrometerController([log])

Provide high-level control for a Keithley electrometer.

KeysightElectrometerCommandFactory()

Format Keysight-specific SCPI commands for RS-232 control.

KeysightElectrometerController([log])

Provide high-level control for a Keysight electrometer.

MockKeithley()

Mock a Keithley electrometer command parser.

MockKeysight()

Mock a Keysight electrometer command parser.

MockServer(brand[, unstable, ...])

Implement a mock server for the electrometer.

ReadingOption(value[, names, module, ...])

The type of data reading.

ScanResult(data, trace_elements, start_time, ...)

Represent data collected during one electrometer scan.

SensorConfig(brand, model, serial_number)

Store sensor metadata associated with the electrometer.

Source(value[, names, module, qualname, ...])

Controls the source setting for triggering data to the buffer.

TcpipConfig(hostname, port, timeout)

Store TCP/IP connection settings for a controller.

UnitMode(value[, names, module, qualname, ...])

The units for the electrometer.

Architecture Notes#

The package separates CSC responsibilities from controller responsibilities.

ElectrometerCsc

Handles SAL commands and events, detailed states, S3 bucket setup, image name service interaction, simulator startup, and large file object publication.

ElectrometerController

Handles common device workflows, including connection initialization, zero calibration, scan setup, scan readout, error queue checks, controller state caching, and in-memory FITS creation.

KeithleyElectrometerController and KeysightElectrometerController

Provide the brand-specific command factories and behavior needed by the common controller workflow.

Commander

Serializes TCP/IP command transactions and reconnects/retries when a command reply is interrupted by a connection drop. It reads replies in chunks until the device terminator is received, which avoids byte-at-a-time reads and handles longer replies such as scan buffers.

The controller does not publish SAL events directly. After calling a controller method, the CSC publishes the relevant event using the updated value cached on the controller.

Build and Test#

setup -kr .
scons

alternatively

pip install .[dev]
pytest --cov lsst.ts.electrometer -ra

Usage#

run_electrometer 1

The command-line commander can be started with:

command_electrometer 1

Simulator#

There is a basic simulation mode. It is mostly meant for unit testing the CSC. Simulation mode starts a mock TCP/IP server for the configured electrometer type and points the controller at that server.

Updating Firmware of the Electrometer#

The firmware for the electrometer is not updatable.

Building the Documentation#

It is assumed that the user is inside the develop-env container. The documentation uses Documenteer 2 with the documenteer[guide] extra. The Sphinx preset is imported from doc/conf.py and project-specific metadata, including intersphinx projects, is configured in doc/documenteer.toml.

The following command will build a local copy of the documentation.

package-docs clean && package-docs build

Contributing#

Code and documentation contributions utilize pull-requests on github. Feature requests can be made by filing a Jira ticket with the ts_electrometer label. In all cases, reaching out to the contacts for this CSC is recommended.

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