9103 Picoammeter Actuel Update: Micro Window Display

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UPDATE: A new Actuel Beta featuring the micro window display is now available.

The Problem: Using Actuel to control and measure current with the 9103 Picoammeter takes up valuable screen real estate:

Actuel is RBD’s Windows application for controlling the 9103 USB Picoammeter. It also provides features like measuring, recording, and graphing current. Although the data recording and graphing display is a separate, optional window, the controller  and measurement window still take up quite a bit of screen real estate.  Sometimes, you just want to display the current unobtrusively while performing other work on your PC.

The Solution: A “Micro” version of the Actuel window that displays only the current and stability.

In response to customer requests, we’ve added a miniature display option to Actuel. By selecting an option in the main window, you can instruct Actuel to display a smaller window when minimized. This windows is much smaller than the main form, yet large enough to be viewed at some distance – a handy feature in many lab environments.

This “micro” window can be moved anywhere on screen and is always displayed on top of other windows. This allows you to use other applications (like RBD’s AugerScan) while simultaneously monitoring current without taking up precious screen real estate. The micro current display window provides a subset of the information available from the 9103 Picoammeter, including the current measurement and polarity, the sampling status, and the range status. There is also an warning overlaid upon the current measurement should the sample be unstable.

If you are using more than one 9103 Picoammeter and running multiple instances of Actuel, you can display a separate window for each 9103. The “micro” window displays the firmware identifier for each individual 9103 picoammeter so you can keep track of which 9103 Picoammeter each display is associated with.

This feature is just one of many additional features coming to Actuel, which will include a data display cursor, and auto-save-to-file while sampling. As always, Actuel is free for all owners of a 9103 Picoammeter! Meanwhile, you can download the most recent version of Actuel here:

Download Actuel for the 9103 USB Picoammeter

More Information on the 9103 USB Picoammeter

Calibrating the 9103 USB Picoammeter

9103 Picoammeter

Calibrating the 9103 USB Picoammeter

The calibration procedure provided with the 9103 USB Picoammeter is written for use with a Keithley 220 current source and is set up for semi-automatic operation. But what if you want to use another brand or type of current source? The following procedure shows you exactly how to calibrate and verify calibration using any current source.

Preparing for Calibration

In order to calibrate your 9103 Picoammeter, you will need a calibrated current source, and software that can send / receive ASCII commands to the Picoammeter. If you are using the Actuel application supplied with your Picoammeter, there is a built in console window that allows you to communicate directly with the Picoammeter using ASCII commands – simply click the Console button to open the window and type the commands in the field provided.

Note that when using Actuel’s console window, the ampersand character “&” that precedes all commands is automatically entered for you – you do not have to type it.

Note also that the offset and gain calibration apply to all 7 ranges. Range 1 corresponds to the highest resolution range in nA, range 7 corresponds to the lowest resolution range in mA. The Gain Reference Table (at the end of this article) shows the ideal calibration values and limits for each range (both positive and negative polarity).

Perform OFFSET Calibration and Verification Calibrate Offset (all ranges)

  1. Ensure that the current input is disconnected
  2. Send command &R0 (auto-range)
  3. Send command &C1, 9103 responds “Offset Calibration starting…”
  4. Wait for completion (about 30 seconds), until message received “Offset Calibration Completed!”
  5. Send command &C0, 9103 responds “OPEN CIRCUIT Offset Calibration starting…”
  6. Wait for completion (about 30 seconds), until message received “OPEN CIRCUIT Offset Calibration Completed!”

Verify Offset for (all ranges)

  1. Ensure that the current input is disconnected
  2. Send the &I0500 command to start receiving data samples
  3. Send command &R# (where # is a number 1 through 7) to manually select the range to be verified (see the Gain Reference Table below)
  4. Verify measured values received are zero and have at least 1 zero after the decimal point
  5. Repeat until all ranges are checked

Perform GAIN calibration

Refer to the Gain Reference Table below for interpretation of the current values and limits.

  1. Send the &+CC command to unlock the calibration function. The green LED will begin flashing
  2. Connect the current source to the 9103 input
  3. Turn on current source. Ensure current source is at proper operating temperature before proceeding
  4. Send command &C2, and wait for prompt from 9103: “Apply test current…”
  5. Using your calibrated current source, input the specified test current (see table below) and send command &C2 again, the 9103 will respond with “Measuring and calibrating gain…”
  6. Repeat the current application for each of the 7 ranges and polarities, following the prompts provided by the 9103
  7. Wait for response from the 9103: “Gain Calibration completed!”

Perform GAIN verification

  1. Send command &R0 (select auto-ranging)
  2. Send command &I0500 (sample interval 500 mSec)
  3. For each test current (shown in the Gain Reference Table below), set the source to the specified current and select the appropriate current range on the 9103 in turn (&R1, &R2, &R3, &R4, &R5, &R6, &R7), monitoring the data stream for at least 10 seconds after each range, and ensuring that the readings are stable in each range (if a message starting with &S* appears indicating an unstable value, wait a little longer)
  4. Verify that the measured value reported by the 9103 is within 1% of the set current for each range
  5. Send command &I000 to stop sampling
  6. Disconnect current source and turn off the 9103 – calibration is complete

Gain Reference Table
(14 test currents are shown, positive/negative polarities for each of the 7 ranges)

Range

Test Current

9103 Value

9103 Value Limits

1

+ 1.0000 –9

1 nA

0.9900, 1.0100 nA

2

+ 10.000 –9

10 nA

09.900, 10.100 nA

3

+ 100.00 –9

100 nA

099.00, 101.00 nA

4

+ 1.0000 –6

1 uA

0.9900, 1.0100 uA

5

+ 10.000 –6

10 uA

09.900, 10.100 uA

6

+ 100.00 –6

100 uA

099.00, 101.00 uA

7

+ 1.0000 –3

1 mA

0.9900, 1.0100 mA

1

1.0000 –9

1 nA

-0.9900, -1.0100 nA

2

10.000 –9

10 nA

-09.900, -10.100 nA

3

100.00 –9

100 nA

-099.00, -101.00 nA

4

1.0000 –6

1 uA

-0.9900, -1.0100 uA

5

10.000 –6

10 uA

-09.900, -10.100 uA

6

100.00 –6

100 uA

-099.00, -101.00 uA

7

1.0000 –3

1 mA

-0.9900, -1.0100 mA

Programming the 9103 Picoammeter

Programming the 9103 Picoammeter

Progamming the 9103 Picoammeter

RBD’s 9103 USB PIcoammeter is packaged with Windows application software for control, current display, data-logging, and graphing. However, it’s often desirable to use the 9103 with other operating systems, integrate it with other hardware or software systems, and/or extend the capabilities of the application software. Fortunately, the 9103 utilizes an ASCII command set that exposes all of its features. Programming the 9103 Picoammeter is straightforward and easy to test.

A complete guide to programming the 9103 picoammeter can be viewed and downloaded  from RBD’s website here. This post will give you an overview of setting up communications with the 9103 and the message structure for controlling the unit and gathering status and data.

Of course, every programming environment is different. As long as you are working with a tool that supports USB communication and text streaming, you can create a custom application for your 9103.

Setting up Communications

If you are using your 9103 with Windows, the installed driver creates a virtual serial COM port. RBD’s Actuel application software uses this port for communicating with the 9103, and any application you use to interface with the 9103 will use this same port for communications.

For other operating systems, you’ll need to download the appropriate driver from the manufacturer of the USB communications components, FTDI. Those drivers can be found here.

If you are interfacing the 9103 with LabView, drivers and scripts can be found on the 9103 downloads page.

Communications Protocol

The communications protocol for the 9103 is typical for many serial devices. Whether you configure the USB port using your operating system or program it within your application, the protocol is as follows:

Setting

Value

Bits per Second (Baud Rate)

57600

Data Bits

8

Parity

None

Stop Bits

1

Flow Control

None

Sending and Receiving Commands

Communication with the 9103 is asynchronous. Most commands sent from the computer control device to the Picoammeter will be answered with a response, which may include an error message if there is a problem understanding/executing the command.

All messages are delivered as ASCII text – there is no binary message data. This includes the actual data delivered by the 9103, which is a formatted ASCII value.

Depending on your programming environment and application, you’ll normally be coding (at the least) logic to deliver the messages to the 9103, as well as to monitor the USB port and parse incoming messages.

Message Formats and Sample Messages

All messages are preceded by the “&” character, followed by a single character denoting the command or data type, as well as additional characters representing command parameters or data.

Here are a few examples:

I – From PC, command message to set the data sample interval, parameter is in milliseconds, 0015 to 9999.Example: ‘&I0500‘ sets the sampling interval to 500 milliseconds
F – From PC, controls the filter settings for the sample data. Allowed values are 000, 002, 004, 008, 016, 032, and 064.Example: ‘&F016‘ sets the filter value to 16

Data and status are passed back to the PC from the 9103 using a similar format. For example:

E - From device, sent if there was an error. Includes string description of error.

A full description of the command and data messages, as well as additional information on programming the 9103 Picoammeter are found in the 9103 User Guide.

 

Using Actuel’s Console Window For Debugging

If you are communicating with the 9103 using Windows, you can view the communications taking place in real-time using the Console window – simply click the Console button on the main window. You can also type commands here and see the results in real-time.