Does the A&D AD-1688 weighing data logger also work with scales from other manufacturers?

What is the A&D AD-1688 weighing data logger?

It is a compact device designed to be connected to scales and balances made by A&D via their RS-232 interface. It stores the weight and – if required – a sequential number and the date/time. After weighing, it is connected to a USB port on a computer (just like a flash drive) to access the data:

data logger ad-1688 connected to pc

The CSV file created by the AD-1688 can be opened in applications such as Excel by simply double-clicking on it. The weight will appear as a number in its own column, ready for further processing.

Does the data logger work with scales from other manufacturers?

Sometimes, but it almost never works as well as with scales from A&D. In our tests, the following problems occurred.

Connectors and pinout

Weighing data logger AD-1688 connectors
Connectors of the cables included with the AD-1688 weighing data logger

The data logger comes with suitable cables for (almost) all scales and balances made by A&D. On a DE9 connector (often erroneously called DB9), it uses pins 2 (RxD), 5 (GND) and 6 (DSR), though the latter is not strictly necessary. To connect to scales from other manufacturers, you may need adapters such as “gender changers” or null modem adapters, or you may need to make a special cable:
rs232 gender changer null modem adapter

Please do not assume that the pinout is compatible just because the connector can be plugged in on your scale!

Possible damage

Some scales use pins of the RS-232 port for other purposes, e.g. for powering peripherals such as check weighing signal lights. These pins must not be connected to the AD-1688!

Power supply via the RS-232 interface

The AD-1688 gets its power from the scale it is connected to (or the USB port when connected to a computer). RS-232 voltage levels are clearly defined in the RS-232 standard. Nevertheless, the “RS-232” interface of some scales does not supply the voltage required to operate the AD-1688. On a Kern DE parcel scale, for example, the data logger did not turn on at all, even though the pinout matched:

ad-1688 weighing data logger and kern de scale
AD-1688 weighing data logger conencted to a Kern DE parcel scale

Further analysis revealed that this scale did not contain an RS-232 transceiver and that logic one (“mark”) was sent as 0 V (instead of −15 to −3 V).

Interface parameters

The settings for baud rate, number of data bits and parity must match on the scale and on the data logger, otherwise the AD-1688 won’t be able to read the incoming data correctly.

When using the data logger with scales from A&D, you do not have to worry about this: Almost all A&D weighing instruments use 2400 bps, 7 data bits, parity “even”. This is also the default setting of the AD-1688.

For scales made by other manufacturers you will have to change the interface parameters either on the scale or on the data logger. The AD-1688 supports the following settings:

  • Bit rate: 600, 1200, 2400, 4800, 9600, 19200.
  • Data bits/parity: 7 even, 7 odd, 8 none.

Data format

The data logger expects all data to be sent as ASCII in A&D’s standard format:

First line: byte number; second line: ASCII character sent by an A&D balance; third line: hexadecimal value
 1 2 3 4 5 6 7 8 91011121314151617
ST,+00456.89gCRLF
53542C2B30303435362E38392020670D0A

Only a very small number of scales made by other manufacturers support this exact format. If your scale sends data in a different format, two problems may occur:

  1. Unless each line is terminated with carriage return and line feed, the AD-1688 won’t record it.
  2. Even if this is the case, the numeric value of the weight will not be separated from the unit (and other characters sent by the scale).

You can generally solve the second issue by using the import wizard of your spreadsheet application. With Excel, the easiest way to open the file in the import wizard is to rename it from .CSV to .TXT.

You can try this out yourself by right-clicking here and downloading a (renamed) file we recorded on an AD-1688 connected to an Ohaus Catapult 5000 scale. This is the scale shown in the header image of this article.

Number of lines

Many scales send several line breaks after the weight (for the paper feed of a serial printer). This causes the data logger to create empty rows not containing any data. If you cannot modify the line feed configuration of your scale, you can instead increase the “Line” setting of the AD-1688 to combine several lines into one row.

This will result in empty columns (see example file above), which is much better than empty rows. However, the maximum is 7 lines. Beyond that, data will spill into the next row.

Decimal point or comma

The AD-1688 data logger cannot convert between a decimal point and comma. If you’re in a country which uses a decimal comma, this again means that you will have to use the import wizard of your spreadsheet app to correctly format the weight as a number.

Note: A&D scales let you choose whether the weight should be sent with a point or comma (e.g. “12.34″ or “12,34″) and therefore do not have this problem. You only have to ensure that the “dP” setting on the data logger matches the decimal separator used by your scale.

Transmission mode

Most scales have a “print” or “data” button to send a single weight reading to a connected device. However, this is not always the case. Some scales send the weight continuously with several values per second. This would quickly fill the memory of the AD-1688. You can mitigate this by using the “Rec” setting so that data is only stored at certain intervals, but this is far from ideal for most applications.

Other scales use bi-directional protocols (very common with point-of-sale scales):

nci pos protocol
Example: NCI POS protocol

Such scales can definitely not be used with the AD-1688 weighing data logger as it can only passively record incoming data. It is unable to send requests to the connected scale (see pinout above, there is no transmit pin).

Intended use according to A&D

Finally, the manual (PDF) clearly states that the AD-1688 is designed to be connected to “balances and scales with an RS-232C connector manufactured by A&D“. It was never intended to be used with weighing instruments made by other manufacturers. Given the many pitfalls described here, this is an understandable decision.

Conclusion

The trouble-free operation of the AD-1688 weighing data logger is only guaranteed with compatible scales from A&D.

On scales from other manufacturers, the AD-1688 may work, but there are many potential problems that can cost you a lot of time. Even in the best case, the resulting CSV file will often not be fully comma-separated due to differences in the data format and will require further processing.

If your scale is not made by A&D, consider connecting it to a PC for data acquisition. You can use our Simple Data Logger software, which is designed to work with scales from many different manufacturers.

Note: The information in this article is valid for firmware P1.10 of the AD-1688.

Links and further information about the AD-1688 weighing data logger

Reading force measurement values from A&D’s LCCU-21 button load cell

A&D’s LCCU-21 USB subminiature button load cells are available in capacities ranging from 100 N to 1 kN. Their tiny size makes it easy to incorporate them into your own machinery or test equipment. They are connected to an A/D converter with a USB interface, enabling you to quickly build PC-based force measurement and data acquisition systems at a very affordable price.

A&D LCCU21N100 usb button load cell

LCCU21 device profile in Simple Data Logger

As an alternative to A&D’s free WinCT-DLC application, you can also use these load cells with the most recent release of our Simple Data Logger software (SDL v1.2.1). In this article, I’ll show you how to configure SDL to request data from the load cell in user-defined intervals (polling).

The LCCU-21 button load cell has two data transfer modes: continuous transfer of up to 100 values/s and a command/reply mode. Currently, only the second mode is supported by Simple Data Logger (continuous mode has to be started and stopped by sending special commands to the LCCU-21, which is something that will be available in a future version of SDL).

Force measurement using A&D’s LCCU-21 button load cell and Simple Data Logger

1. Download and install Simple Data Logger.

2. Go to the license tab and enter a license key (required for the polling function). You can purchase license keys from FastSpring through a completely automated process (including a “90 days” license for only US$5). You can also contact us if you require a free trial license or apply to become a reseller if you want to sell our software to your customers.

3. In the input tab, set the device to “A&D LCCU21”, then click on set default parameters for device. This will set all interface parameters for you. The only thing left to set is the (virtual) COM port which appeared on your PC after connecting the LCCU-21 to a USB port (see this PDF document for further information):
A&D LCCU-21 usb button load cell: configuration in input tab

5. Switch to the control tab, enable polling and set the timer to a value that makes sense for your application. Click on set default command for A&D LCCU21; this will automatically enter the “RLMV” command which will be sent to the USB button load to request measurement data:
Set default command for A&D LCCU-21 usb button load cell

6. Select a file in the output tab. Click on the set values button to automatically set the values below for your region so that you can easily open the CSV file in Excel later. If you want to record the time with milliseconds, choose the appropriate format from the drop down list or enter it manually:
CSV file format settings

7. Click on the start button in the start tab to connect to the LCCU-21 USB button load cell and to start sending the polling command. Commands and replies are shown in the event log. Captured measurement values appear in blue and are written to the CSV file. Click on stop to stop data acquisition and to close the file:
Data acquisition from A&D LCCU-21 usb button load cell

Notes on the LCCU-21 button load cell

  • I don’t have the LCCU21N100 I used for testing anymore, so if you have any questions about it, please contact A&D.
  • The product brochure (PDF) contains several creative application examples, including one where load is applied by pressing the button load cell with a finger. When I tried this, it worked, but not very well: I found that it is impossible to press only the load sensitive surface (though maybe that’s not an issue for people with smaller fingers). It is therefore advisable to “apply load to the load cell through a rigid surface” as stated in the user manual.

Further information

Ohaus Ranger 7000: can a scale simplify complex weighing applications?

“Simplifying even the most complex industrial applications” is the claim that Ohaus makes in their data sheet. Is it justified? After spending some time trying out the different functions of this scale, I believe that yes, it is.

The key to understanding the power of the Ohaus Ranger 7000 scales are the 10 application modes:

  • Weighing: Determine the weight of items (no surprise here). A statistics feature can be used in weighing mode to calculate statistical data.
  • Counting: Count parts of uniform weight. Auto-optimization recalculates the average piece weight as the number of pieces is increased.
  • Check weighing and check counting: Compare the weight or count of a sample against target limits. Connect with discrete I/O option kit to use external check lights.
  • Formulation: For compounding and recipe making. Compensation can be used in case a component is overfilled (outside the tolerance).
  • Percent weighing: Measure the weight of a sample displayed as a percentage of a pre-established reference weight.
  • Filling: Fill a container to a target weight. Progress bar displays filling status. Connect with discrete I/O option kit to control a semi-automatic filling system.
  • Dynamic weighing: Weigh an unstable load. Scale takes an average of weights over a period of time. Can also be used as a display hold function.
  • Density Determination: Determine density of solids.
  • Differential weighing: Calculate the difference between sample weights and initial weights.
  • Sieve analysis: Used to assess the particle size distribution (also called gradation) of a granular material.

Each application is displayed differently on the 4.3 inch color screen. Compare, for instance, the display in weighing mode to check counting mode:

Weighing application on Ohaus Ranger 7000 scale
Weighing
Check counting application on Ohaus Ranger 7000 scale
Check counting

The applications are not limited to different presentations:

  • Five physical smart buttons below the display take on different functions depending on the application.
  • All settings relevant to the current application can be accessed easily by pressing the settings button.
  • The internal library allows you to save application specific data for commonly used items (e.g. the target weight and tolerance for check weighing, the average piece weight in counting mode or the set points in filling mode). The scale can be connected to a bar code reader to simplify recalling data from the library.
  • An optional I/O kit with four outputs (relays) and 2 inputs can be used to integrate the scale with external devices. The functionality is again dependent on the application mode. One of our customers has used the filling application with the I/O kit to build filling machines controlled entirely by a Ranger 7000 scale.

Therefore, as long as your application is supported by the scale, it does an excellent job at simplifying many tasks.