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| Rigol DP832 remote command update rate????.............. |
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| Smokey:
My setup is I'm using the LXI LAN connection on the Rigol DP832 power supply to a python script setting the voltage and reading the current. I'm trying to essentially do a voltage sweep incrementing the set voltage on one channel (gate) and reading the current back on the other channel (drain) to make a curve tracer of sorts. The problem is I can't reliably do a set_voltage+read_current cycle in less than about 0.7seconds, which would make the test take WAY too long. Is this just the fastest I can set and read from the instrument or is there something else I can do? I'm open to other communications data capture methods if that's faster. |
| LaurentR:
Can't find anything in the manuals, but I have a similar experience. A couple of years ago I ran sweeps across the voltage ranges to characterize the setting and measurement error (drive with the DP832, read with the DP832 and a 3446x and compare) and settled on a 1.5-2 sec cycle time as the response from the DP832 was slow. Note that in all the native sequencing available from the front panel, all times are in seconds (no fractions of a second), so it doesn't natively do anything fast. Not sure where the delay is. |
| RoGeorge:
--- Quote from: Smokey on October 12, 2017, 03:37:40 am ---I'm trying to essentially do a voltage sweep incrementing the set voltage on one channel (gate) and reading the current back on the other channel (drain) to make a curve tracer of sorts. --- End quote --- I guess the best approach to do that will be to use the "Timer and Delay" internal feature of the DP832, then use LXI to read all channels measurements at once while drawing the charts on the PC. "Timer and Delayer" is described in the user manual, it has the possibility to output automatically a custom defined "waveform", or predefined waveform like sinus, pulse or ramp. LATER EDIT: Sorry, the minimum time for each output value is 1 second, so I guess the timer feature doesn't help. Another option You could try to use a kind of hack, based on the assumption that the LXI reading of the measurements is faster (I didn't tested how fast the measurements can be read): - set a very low current limit, like 5mA, for the channel destined to feed the gate with voltage - then, turn the channel from 0 to something like 10V - this will create a voltage ramp at output, because the filter capacitor from the output of the channel is big, so it will take some time to charge up to 10V with only those 5mA. - while the voltage is raising at the channel that feeds the gate, start reading as fast as possible the measured values for the gate voltage channel and for the current drain channel. Maybe this will work fast enough to make a curve tracer, but I didn't tested it. |
| RoGeorge:
It happens that I am working right now on something similar with what you are doing. I just found that the measured values are updated only twice per second. I can request by LXI the measurements much faster, even 100 times per second, and it will respond, but it will respond with the last measured values, so I can not have more than 2 distinct measured values per second. It seems that a curve tracer can not be done faster than 1-2 steps per second. :-\ |
| Smokey:
Damn. That all matches with what I've been seeing. That sucks. I wonder why they didn't allow faster remote updates. Time for plan B.... |
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