SDM3045X SCPI poll rate - Page 1
Forum section: electronics / testgear

author: Perkele
author_rank: Regular Contributor
timestamp: July 25, 2023, 08:35:06 am
content: What is the fastest readouts poll rate on SDM multimeters via SCPI over LAN? Sacrificing precision for speed is acceptable.SDM3045X multimeter is connected to a PC via LAN patch cable, there are no network switches or routers between them.I'm getting between 40ms and 45ms per readout.Setup commands:CONF:CURR:AC 0.6CURR:AC:NPLC 0.3CURR:AC:NULL 0TRIG:COUN 1TRIG:DEL 0TRIG:DEL:AUTO 0TRIG:SOUR IMMSAMP:COUN 1Values (AC current) are read by executing:INITDATA:LAST?This is a simple single-thread application, and now the requirement is to reduce SCPI read time.I have read the manuals and I am aware that it is possible to set-up the trigger so that the instrument's buffer is filled with measurements at a rate defined by NPLC.But at the moment I don't have the instrument here with me to properly test the code changes.

author: alm
author_rank: Super Contributor
timestamp: July 25, 2023, 11:31:19 am
content: I think the big improvement will indeed be reading into a buffer and retrieving the entire buffer at the same time. Doing a command per reading is never going to be fast. Usually system multimeters have a section in the manual about optimizing reading rates.You might be able to achieve a tiny gain by switching to a more compact output format like binary instead of text. Double check if the meter disables auto zero in ACV mode. Otherwise that could help performance.

author: delvo
author_rank: Contributor
timestamp: July 25, 2023, 12:42:06 pm
content: Try setting TRIG:COUN INFand then loop R? 10000 to get the last 10000 readings (or less if there is less in the buffer). That should be a lot faster and you will probably be limited by the sample rate of the multimeter instead of the LANEdit: Just noticed you were reading AC current. That is really not that fast. I also dont think you can set the NPLC and auto zero for that. I dont think they do anything. The only setting that increases the speed of AC current measurements is the bandwidth and i dont think you can set that on a 3045X

author: KungFuJosh
author_rank: Super Contributor
timestamp: July 25, 2023, 02:33:39 pm
content: I don't know if this helps your quest or not, butimprovingthe SDM3045X to the SDM3055X-E makes other things better. 😉

author: Perkele
author_rank: Regular Contributor
timestamp: August 07, 2023, 07:50:23 am
content: Thank you for the answers.Removing auto-zeroing in order to speed things up was mentioned in the manual and on some other forums.Reading the buffer seems like the only way out, but wanted to avoid it until I get that meter onto my desk.Upgrading the firmware is out of question because it's someone else's device.

author: tautech
author_rank: Super Contributor
timestamp: August 07, 2023, 07:56:37 am
content: Quote from: Perkele on August 07, 2023, 07:50:23 amJosh speaks of changing the model, yes it is done by fooling the meter to accept another model firmware however any instrument tests/checks should always be done with the latest firmware installed which is 09R2https://int.siglent.com/upload_file/zip/firmware/A_multimeter/SDM3045X_V5.01.01.09R2.zip