High-speed Support Improved in Latest Actuel Release (1.7) for the 9103 Picoammeter

RBD has released Actuel version 1.7 for the 9103 Picoammeter, with improvements for high-speed data acquisition and (especially) data logging and graphing.

The latest version can be found here.

If you do not have a high-speed 9103 Picoammeter and are already running Actuel version 1.6, there no reason to download the latest version. However, high-speed users will find a number of improvements.


Oscilloscope emulation


Although Actuel was not designed to have an oscilloscope emulation (with features such as triggering), at higher speeds you can come close to emulating scope current monitoring.

In the Data Window, click the Show Options button and select “Last” from the Graph Options. You can scroll in increments as low as 0.1 second, but you can type in a smaller increment, such as “0.05” in order to display at higher resolution.

Last time option in Actuel
Using the “Last” time option in Actuel


(Note: The graph display options can get out of sync with data collection if you change and option when recording or after stopping and clearing data – it may be necessary to re-enter the value or reset recording. We’re working to make this smoother in the next version.)

For smoother real-time graphing, use standard-speed at 25 mS unless faster rates are needed

The 9103 can run as fast as 25 mS per sample in standard-speed mode, and 2 mS per sample in high-speed. In order to optimize faster data acquisition in high-speed mode, the 9103 collects 10 samples per message, as opposed to 1.

However, note that if you are collecting data at 25 mS in Standard-speed, your PC will be updated with new data every 25 mS. In High-speed, you’ll be updated every 250 mS.

For that reason, the Acutel software always collects data in standard-speed mode at 25 mS and above, regardless of the high-speed mode settings. It is recommended you do the same if you are writing your own software to control the 9103.

That also means that for real-time graphing, you may not want to sample at a rate of, for example, 24 mS, if you can achieve the same results at 25 mS. At faster rates, the delay in caused by receiving 10 samples per message is less noticeable, but it’s visible at rates of 20 mS- 25 mS if you are graphing only the latest points in relatively high resolution:

Actuel 25 mS Standard Speed

Actuel – 25 mS Standard Speed

Actuel 25 mS High Speed

Actuel – 24 mS High Speed

9103 USB Picoammeter Filter Settings – Part 1

The 9103 Picoammeter uses a continuously sampling A/D when measuring current. These samples are then averaged using an low-pass infinite impulse response (IIR) filter.

Filter Settings

When using the 9103 to sample current, you have control over the filter response and the degree of smoothing (both in Actuel in when programming the unit). The filter setting will make little difference for most constant signals, but for dynamic and periodic signals, the filter can be set to attenuate noise, or to provide detail and catch peaks.

A filter coefficient that is user-programmable determines the amount of smoothing the filter will apply. The higher the value, the more smoothing of the signal.

The filter can be set to 0, 2, 4, 8, 16, 32, and 64. A value of 0 is essentially the same as bypassing the filter. A value of 64 is the greatest amount of filtering. For most cases, values of 4, 8, and 16 will work best. Higher values may produce more accurate results for stable signals, but it will take longer for measurements to stabilize.

Example

In the examples below, a 1 Hz sine wave is sampled at a 25 mS rate, yielding 40 discrete data points per cycle. Each data point is comprised of multiple filtered A/D readings.

The filter settings used in the examples are 2, 4, 8, 16, and 32.

filter setting 2
Filter Setting 2
filter setting 4
Filter Setting 4
filter setting 8
Filter Setting 8
filter setting 16
Filter Setting 16
filter setting 32
Filter Setting 32

There’s quite a bit of noise present when using low filter values of 2 and 4, while values of 16 and 32 reduce the noise but also attenuate the signal somewhat. For this application, a value of 8 produces the most accurate result.

Conclusion

In general, any low-pass filter will of course mask high-frequency data. While the 9103 is not typically used to measure periodic signals, the filter’s effect on your application may be significant. When in doubt, start with the filter set to 8 for some noise reduction without significant smoothing or signal attenuation.

In Part 2 we’ll discuss use of the additional first-level filter implemented in the high-speed model of the 9103.

9103 USB Picoammeter Winter 2020 News

Last year, RBD introduced an updated 9103 USB Picoammeter, with 3 new models:

  • High-speed: 500 reads / second compared to 40 for the Standard Model
  • High-voltage: an isolated signal input with the ability to float the 9103 Picoammeter to ±5000 VDC.
  • High-speed / High Voltage: One model combining both features.

This year we’ll be working on adding new features to our Actuel application software and providing more comprehensive support and programming documentation.

Actuel 1.6 is Released

Actuel Version 1.6
Actuel Version 1.6


The latest version of Actuel (1.6) is now available, as is an updated User Guide. The guide has new information on setting up and programming the 9103 for high-speed communications. Both can be found here.

This release replaces the Beta release and has full support for high-speed sampling and data recording and graphing.

9103 TechSpot Article Series

This year, we’ll be running a series of articles here on the TechSpot blog with more information on the new 9103 models and features, as well as detailed configuration, application, and programming advice.

Some of the topics we’ll be covering include:

  • Programming the 9103 for high-speed data collection
  • Using the high-voltage reference
  • Proper use of the input ground
  • Troubleshooting 9103 communications

Keep your eye on here on TechSpot for these and other articles covering all of RBD’s products, and please consider subscribing.