Thanks, Roehrenonkel.
As far as Local / Remote, I am hoping to avoid the mode switch and the controls and displays needed for it. I am trying to simplify things, but maybe I'm missing something.
My plan is to allow instrument settings to be done any time by either the operator or SCPI. Let the operator beware. The only place that a real conflict exists is when doing ADC measurements. These take some time time and need to be synchronized, particularly to SCPI requests.
I was thinking of something like 'Scope Auto-Trigger'. The ADC re-triggers automatically, making measurements continuously. If a SCPI Read occurs, it takes priority, then the instrument waits (like ~1 Sec) for another SCPI Read. If no read occurs before that time, the instrument reverts to continuous reads. So SCPI has priority. This is so an external host can perform a fast sequence of Force/Measure operations. This is where the instrument needs to operate at its fastest speed.
Currently the firmware measures both current and voltage every pass, which slows things down 2x. After a SCPI Read, only V or I would be read to save time. I'll need to blank the other one on the display.
I'd be interested to know what you or others think of this approach.
Thanks,
Dave
Hi Dave,
On a Range-change upwards the value will be multiplied by 10. Not so safe.
Is it because of my dry-run without ADC-/DAC-chips?
"Let the operator beware." ..even with +-150 Volts?
Operators get tired and make mistakes, automated tests can run errorfree for ages.
Local/Remote:
Imho in Remote-mode no user-inputs except the "Local/Remote"-Key should be read.
This is to prefent intended or unintended user-inputs messing up messurements.
I see that it is not too easy to implement in the current versions (hw+sw).
An indicator and switch plus the software is needed here.
For "Output On" a LED (at Interface-potential) also would be nice.
Maybe consider two modes (Fast/Precise).
As long as no clamp-condition is set the force-value
doesn't have to be read, it equals the Set-value, correct?
In precise-mode all monitors would be read with the highest resolution.
A HW-Lockout can easyly be made by a switch/link in the supply-line to the
Output- and Sense-relays and is usable for Emergency-stop, no fixture connected,
safety-hood (like on the Tektronix 370/576 curve-tracer) not closed.
V-ref+: I'll buffer the positive V-ref with an OP for the dynamic loads (ADC/DAC).
Finally i've found relays that meet the microvolt- and picoamp-requirements.
Minimum switching-voltage and -current are rarerly given in data-sheets.
But i hope these mercury-wetted reed-relays made in 1985 will do the job for me.
Have to put them on an external pcb for the upright/vertical orientation.
One more board, but gives more flexibility too.