I want to start a waveform that i set up using the front panel input of my Keithley 6221 with an externally applied TTL input signal. I connected my TTL signal to the Start of Test Input on the digital I/O port and set the Arm-Layer -> Arm-In to STEST Up/Down but nothing happens. I tried pre-arming the waveform and also different variations of the Arm-In settings, but unfortunately to no success. It seems like the 6221 is not (yet?) listening on the SOT port...
I would be very thankfull for your help.
Thanks in advance, Thomas
there is a limitation when using WAVE functions; let me quote the reference manual:
'The trigger models control when to switch to the next point in a SWEEP and how many sweeps to perform.
Note that the trigger configuration does not affect other Model 622X operation including normal output
currents and Model 6221 WAVE FUNCTIONCS.'
Here trigger are available the other way round in form of a phase marker.
Just to make sure I understand you correctly: It is not possible to start a wavefunction on the 6221 using the SOT input.
I am sorry, but I don't think I understand your suggestion concerning the Phase Marker. If I understand the manual correctly, the phase marker will provide a trigger OUTPUT signal from the Keithley, not an INPUT to trigger the unit. Did I understand that wrong? Just to further clarify: What I would like to do is to tell the keithley WHEN to start the waveform generation, I don't what to trigger the signal in any way, the internal triggering is perfectly fine for my purpose. I would like to set up e.g. a square signal for 5s using the front panel and then send a TTL signal from an external source that results in the Keithley starting the waveform. After finishing the signal generation (after the 5s) it should wait once again until it retrieves the next TTL signal and then start generating again.
Is there any way to do this with the Keithley 6221?
Thank you very much for your support,
as the external trigger does not work this way you could consider
- an additional relay (in series to the output of the 6221) which would be activated by a 5 second monoflop triggered by your signal
(quite a hardware effort)
- PC instead of manual operation (get the PC to 'know' your trigger and start the waveform as needed &c.)
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