Keithley 6500 parameters had invalid SCPI commands

[qSaevar]

Changes proposed in this pull request:
In Keithley_6500 driver fix parameters:

• trigger_source
• trigger_delay
• display_enable

@astafan8

[codecov]

Codecov Report

Merging #1541 into master will not change coverage.
The diff coverage is n/a.

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  Misses       3450     3450

[jenshnielsen]

It looks like the dmm supports compatibility mode with old dmms. I suspect the original driver was written to support this

[qSaevar]

@jenshnielsen It is stated in the class docstring that this is based on the keithley 2000 (where the SCPI commands are valid) and that this is a bet-version. Don't know if there has been a 6500 in the past where the three parameters that I changed worked. My guess is not.

[astafan8]

Looks OK (module Jens' comment). Left some minor suggestions.

[jenshnielsen]

@qSaevar Yes my point is that the 6500 can be put into a 2000 compatibility mode. I think that could be what this driver is targeting. See #1533 for something similar example for the the 2450

[qSaevar]

@jenshnielsen Ok, I see you point. So, solutions: Flag in the constructor for compatibility mode set by the user? Second driver for the full feature support? Some auto detection for the mode the device is in?

[jenshnielsen]

@qSaevar Yes I think we should test which mode it's in and error appropriately if it's in the wrong mode. I support using the default mode and not any compatibility mode

[qSaevar]

@jenshnielsen ok, so I'll add something like:
if language not SCPI:
raise MeaningfulError
At the end of the constructor.

[qSaevar]

I did add a check for the correct command set.

[qSaevar]

@astafan8 I addressed your comments, @jenshnielsen concerns and updated the branch. Is there anything else that needs to be done?

[astafan8]

It looks good now module one comment. After it is fixed, i'll merge.