Multi-channel multimeter with USB interface? - Page 1
Forum section: electronics / testgear

author: SiliconWizard
author_rank: Super Contributor
timestamp: July 13, 2023, 09:54:35 pm
content: I'm looking for some kind of multi-channel multimeter, controllable via USB, with voltage (and ideally current) measurement.For voltages, they can all have a common reference. For currents, it would need to have a floating connection. But if such a beast is hard to find or doesn't exist, I can do with just voltage measurement - I'll add some current-to-voltage circuitry.- 4 channels min. for voltage measurement, ~0.1% max error, range from a few tens of µV to about 5V.- 1 channel min. for current measurement, ~0.5% max error, range from a few tens of nA to about 1mA. As said, this part can be done without if hard to find in a single device - then at least 5 channels of voltage measurement would be required.Ideally, the USB interface would come with a simple API to program the device on potentially Linux, macOS and Windows.Some could say that "USB oscllioscopes" might do here (if just for the voltage measurements), but I don't know of any (at least reasonably priced) that would have max. 0.1% error in amplitude, and support low input ranges down to a few tens of µV. Hence why I called that more "multi-channel multimeter".Some others could say, just buy several multimeters with an USB interface. I would prefer a single device.Regarding price, $1000 to $1500 would be good.Note: I know and have used the LabJack T7 in the past:https://labjack.com/products/labjack-t7it was good for production testing of a simple product, but I'm looking for something a bit more polished and more accurate.

author: Martin72
author_rank: Super Contributor
timestamp: July 13, 2023, 10:02:10 pm
content: Hi,What about a multimeter with scannercard ?Siglent for example offer a scannercard for their 5.5 digit meter, with 12 multipurpose channels and 4 current channels.

author: thm_w
author_rank: Super Contributor
timestamp: July 13, 2023, 10:09:37 pm
content: Did you see the T8?https://labjack.com/products/t88 isolated channels.Then there is the DMM6500 with DIY/used scanner card, but that is above your budget.Then the older Agilent DAQ stuff but it doesn't have USB (34970A).The siglent card Martin mentioned seems quite reasonably pricedhttps://siglentna.com/product/sdm3055-sc/($745)https://siglentna.com/digital-multimeters/sdm3065x-6-%C2%BD-digits-dual-display-digital-multimeters/($995)https://siglentna.com/product/scan-card-option/

author: SiliconWizard
author_rank: Super Contributor
timestamp: July 13, 2023, 10:26:50 pm
content: Thanks.- I'm going to have a look at the Siglent stuff.- I did see the T8. Might be a candidate. Plus is: reasonably priced, I already know their products. Minus: not quite as sturdy as regular lab equipment.- I'm going to have alook at the DMM6500 anyway as well, in case I can get a higher budget for this.

author: Martin72
author_rank: Super Contributor
timestamp: July 13, 2023, 10:37:06 pm
content: Another thing:We (work) have two of the hioki datalogger, super small size, 10 isolated channels, via software you can control/monitoring up to 50 channels.Good accuracy, but only voltage or temperature input, so for current measures a shunt would be needed.https://www.farnell.com/datasheets/2847482.pdf

author: tautech
author_rank: Super Contributor
timestamp: July 13, 2023, 10:47:41 pm
content: Quote from: SiliconWizard on July 13, 2023, 10:26:50 pmSC models must be purchased as such as the SC option cannot be added later.https://siglentna.com/wp-content/uploads/2017/12/SC1016_Datasheet_DS60030-E02A.pdfFor USB or LAN use, SDM models can be used with free EasyDMM SW or with SCPI scripts.

author: SiliconWizard
author_rank: Super Contributor
timestamp: July 13, 2023, 10:54:55 pm
content: Saw that. Thanks.The scan card seems out of stock though:https://siglentna.com/product/scan-card-option/

author: bdunham7
author_rank: Super Contributor
timestamp: July 13, 2023, 11:12:23 pm
content: Quote from: SiliconWizard on July 13, 2023, 10:54:55 pmThe -SC will come with a scan card. You'd only need extras if you wanted to prewire them and exchange them for different setups.

author: switchabl
author_rank: Frequent Contributor
timestamp: July 13, 2023, 11:23:46 pm
content: NI USB-6341 or cDAQ-V1100 maybe? They have multiple ranges (+-10V down to +-200mV full scale) and 8 or 16 differential inputs, unfortunately no current inputs. You could build a cDAQ system with an additional current module but that would be way over your budget.https://www.ni.com/docs/en-US/bundle/usb-6341-specs/page/specs.htmlhttps://www.ni.com/docs/en-US/bundle/ni-9205-specs/page/specs.htmlSoftware/API is typical NI, somewhat bloated but works well and has been very stable for me. Documentation is decent. DAQmx API is available on Windows and Linux for C and .NET. Python bindings and Matlab toolbox is also available. (And LabVIEW of course)https://www.ni.com/docs/en-US/bundle/ni-daqmx/page/daqhelp/daqhelp.htmlhttps://www.ni.com/docs/en-US/bundle/ni-daqmx-c-api-ref/page/cdaqmx/help_file_title.html

author: thm_w
author_rank: Super Contributor
timestamp: July 13, 2023, 11:24:58 pm
content: Semi off topic:From Daves teardown they seem to not have the scanner card connection installed in his 3055 unit at all. So thats presumably why its separate, saves a few dollars of parts.Here is a teardown of one with the scan card connector board (looks to be the same connector as used on the DMM6500/keithley units):

author: tautech
author_rank: Super Contributor
timestamp: July 13, 2023, 11:45:47 pm
content: Quote from: SiliconWizard on July 13, 2023, 10:54:55 pmYou can get additional scan cards if/as required.

author: tautech
author_rank: Super Contributor
timestamp: July 13, 2023, 11:50:38 pm
content: Quote from: thm_w on July 13, 2023, 11:24:58 pmYep, this.There's quite a few extra bits and bobs required that includes the mounting tray and fastener HW for the SC.Did some considerable research on this some years back.It quickly became obvious if you want the SC capability purchase that model.

author: tautech
author_rank: Super Contributor
timestamp: July 13, 2023, 11:54:30 pm
content: With some imagination, creativity and a 3D printer you can do this:https://www.eevblog.com/forum/testgear/siglent-new-bench-dmm-sdm3055/msg3070270/#msg3070270

author: Martin72
author_rank: Super Contributor
timestamp: July 13, 2023, 11:56:17 pm
content: WTF!!!???

author: Someone
author_rank: Super Contributor
timestamp: July 14, 2023, 12:12:56 am
content: Quote from: SiliconWizard on July 13, 2023, 10:26:50 pmWe're having troubles controlling the DMM6500 over USB. No way to reset the system state or clear buffers, requiring physical power cycle to recover. Support did not engage or consider the provided test cases, and basically told us to use it the way they imagined it would be (ie, never have any errors or work between reboots/disconnects of the host).So if automation/remote over USB is the primary goal probably best to look elsewhere.

author: SiliconWizard
author_rank: Super Contributor
timestamp: July 14, 2023, 01:24:22 am
content: I've also seen the Pico ADC-24. Downside is that its inputs are limlited to +/-2.5V.

author: Someone
author_rank: Super Contributor
timestamp: July 14, 2023, 03:11:51 am
content: Quote from: switchabl on July 13, 2023, 11:23:46 pmThere are also the "cheap" USB-600x models from NI. Was sure there was a tiny little modular USB chassis that wasn't far off in price but can't find it and NI are aggressively pushing all links to their shop which doesn't show any content in my region

author: switchabl
author_rank: Frequent Contributor
timestamp: July 14, 2023, 11:45:02 am
content: The USB-600x don't have the low voltage range which the OP wants. I completely agree about the NI website, it's absolutely impossible to find anything there. I swear it became even worse when they switched to the new design (green logo) a couple of years ago.I also realize now that Linux support doesn't include the USB DAQs. So if this is a priority, you need to look elsewhere (ideally for something with USBTMC or CDC that doesn't need proprietary driver).

author: joeqsmith
author_rank: Super Contributor
timestamp: July 14, 2023, 11:53:28 am
content: I have a cheap LabJack as well that's very old. Have you looked recently to see if they offer more accurate products that your current one?

author: SiliconWizard
author_rank: Super Contributor
timestamp: July 14, 2023, 08:18:13 pm
content: Quote from: joeqsmith on July 14, 2023, 11:53:28 amthm_w mentioned the T8. The T7-Pro was already not too bad, but not isolated. The T8 is, which is a nice plus. The specs (if they are met) look ok for my needs. Had a deeper look though, and they say the T8 is in some "pre-release" state, with some features unfinished software-wise as far as I got it. Might be a bit too early to go with that.

author: dav888
author_rank: Regular Contributor
timestamp: February 09, 2025, 01:48:29 pm
content: waking up this thread, also on a hunt.- compact form-factor, usb bus-powered- preferably one that goes above +/-10V, say +/-24VNI's USB-6421 are indeed cost-efficient for what you get, but sucks that their usb-protocol is closed and through a binary driver (not possible to run on macOS)---same topic, in case someone looks for din-rail:these are quite nice (schematic fully open source)https://revolutionpi.com/shop/en/analog-io-expansion-module, but you need to also use their rpi cm4/5 unit which integrates well.

author: tooki
author_rank: Super Contributor
timestamp: February 09, 2025, 01:58:55 pm
content: Quote from: Someone on July 14, 2023, 12:12:56 amDo those problems apply to SCPI control over Ethernet?

author: Someone
author_rank: Super Contributor
timestamp: February 09, 2025, 11:50:28 pm
content: Quote from: tooki on February 09, 2025, 01:58:55 pmYes