Electrometer User Guide

This CSC is used to control indexed Keithley and Keysight electrometers. The primary use-case is to read/monitor the electrical signals from a Hamamatsu S2281 photodiode, however it can be used with other devices. The device is generally used in current and charge measuring modes. The CSC communicates over TCP/IP, either directly to an ethernet-capable electrometer or through a serial-to-ethernet terminal server. The CSC creates a FITS file for each completed scan. The FITS file records the measured signal, timestamps, and configured trace fields such as temperature or voltage source data when those accessories are enabled. The file is uploaded through the configured S3 bucket and announced with the largeFileObjectAvailable event.

Electrometer Interface

Link to the XML is located at the top of the index.

Common Commands and Events

The normal scan workflow is:

1. Configure the device through the CSC configuration file.

2. Bring the CSC to ENABLED.

3. Optionally issue configuration commands such as performZeroCalib, setDigitalFilter, setIntegrationTime, changeNPLC, setMode, setRange, or setVoltageSource.

4. Start a manual scan with startScan and finish it with stopScan. Alternatively, use startScanDt to acquire for a fixed duration.

5. Read the largeFileObjectAvailable event to find the uploaded FITS file.

The CSC publishes configuration changes through the corresponding events, including measureType, measureRange, integrationTime, digitalFilterChange, changedNPLC, and voltageSourceChanged. The detailedState event reports whether the CSC is idle, configuring, reading, or reading out the buffer.

Example Use-Case

The following example demonstrates how to instantiate a single electrometer, then perform a reading of an arbitrary length.

from lsst.ts import salobj

domain = salobj.Domain()

electrometer = salobj.Remote(name="Electrometer", domain=domain, index=101)

await electrometer.start_task

await electrometer.cmd_performZeroCalib.set_start(timeout=10)
await electrometer.cmd_setDigitalFilter.set_start(activateFilter=False, activateAvgFilter=False, activateMedFilter=False, timeout=10)
await electrometer.cmd_startScan.set_start(timeout=10)
await electrometer.cmd_stopScan.set_start(timeout=60)
lfo = await electrometer.evt_largeFileObjectAvailable.next(flush=False, timeout=60)
print(lfo.url)

For a fixed-duration scan, use startScanDt instead of startScan and stopScan:

await electrometer.cmd_startScanDt.set_start(scanDuration=5.0, timeout=60)
lfo = await electrometer.evt_largeFileObjectAvailable.next(flush=False, timeout=60)
print(lfo.url)

await domain.close()