Siglent extension

[Thomas-Vreys]

Description

This builds on top of your lothar/siglent branch (upstream PR labgrid-project#1926) and is intended to be picked up there, so the upstream PR can be completed with the open checklist items.

It adds reading the measured power from the device, as suggested by @vermaete in the upstream review:

• siglent backend: query MEAS:POWE? CH<n> in power_show() (new watts key) and add a dedicated power_watts() function. The power is read directly from the instrument.
• labgrid-client power show now prints the power, e.g.:

  Voltage: 5.001V [5.0V], Current: 0.209A [1.5A], Power: 1.045W
  

• Two small fixes in remote/client.py: show no longer queries the PSU twice (the drv.show() result was fetched and then fetched again), and the unused ProgrammablePowerProtocol import is removed.

It also completes the checklist items from the upstream PR:

• Tests for the siglent backend in tests/test_powerdriver.py.
• Documentation: doc/configuration.rst, doc/usage.rst, doc/development.rst.
• Man page man/labgrid-client.1.

How it was verified

• Test suite: tests/test_powerdriver.py.
• On real hardware: verified against a Siglent SPD1305X over TCP with a manual try-out script driving the same backend functions the NetworkPowerDriver.

Checklist

• Documentation for the feature
• Tests for the feature
• The arguments and description in doc/configuration.rst have been updated
• Add a section on how to use the feature to doc/usage.rst
• Add a section on how to use the feature to doc/development.rst
• PR has been tested
• Man pages have been regenerated

Outlook: USB support

I would also like to support USB-connected PSU's. That doesn't fit the current design: the backend is built on NetworkPowerDriver/NetworkPowerPort, which assumes a network transport (host + TCP socket), and the backend hardcodes the TCPIP0::<host>::5025::SOCKET resource string. Since PyVISA can already talk to the same devices via USB0::... resource strings, the cleaner long-term structure is a dedicated SiglentSPDDriver bound to a PyVISA resource, where the transport (TCPIP or USB) comes from the YAML configuration instead of being baked into the driver. I have a first draft of that locally and would propose it as a separate follow-up PR, happy to discuss the direction here.

[Rubusch]

LGTM. Note, I cannot verify reading out Watts, my available Hardware does not offer reading out power directly, so I guess you probably verified it.

• I just noted, you are modifying client and siglent driver, so, there was no need to adjust also the power protocol? AFAIR I needed to add still something to make this work for U and I. Perhaps just double-check this.
• About the tests, also here I'm unsure if this is needed, but reading out Current, Voltage and Power is highly optional. Shouldn't there be a test that, not having these settings around, or just having Voltage and Current around, but not power (...), does not break? Perhaps this is already covered by other tests.

BTW. I highly appreciate your effort, thank you so much! This to me answered now many questions on how to document and how integrate the test setup. I'm sorry that you needed to fixed actually the not-so-fun parts (documentation and tests) for me.

[Thomas-Vreys]

I did make another PR: #2 where I answered your comment.