SDL receives data sent from a device connected to your computer and writes it to a file. It currently supports devices connected to a COM port (RS-232, USB virtual COM port, Bluetooth SPP) which send data in ASCII format. It can either capture all printable characters (suitable for devices like bar code readers) or the first numeric value it encounters (suitable for measurement instruments like scales and balances). It can optionally add the date and time to the recorded data and transform the decimal separator of numbers from a dot to a comma (if required).
Files written by Simple Data Logger can easily be opened in Excel or other spreadsheet applications.
232key uses pre-defined regular expressions to match the data coming from the connected device and to capture the value you’re interested in. In this article, we’ll demonstrate the use of custom regular expressions (available in the paid Plus version) to capture the (net) weight from a balance and avoid capturing values we do not want to be typed. The instructions posted below can be applied to all kinds of serial devices (not only balances and scales).
When 232key captures too many values
For this example, we’ll be using an Adam Equipment HCB 3001 portable precision balance. It’s equipped with an RS-232 and USB interface. Either one works with 232key:
232key comes with a device profile for this balance. When you select it in the input tab and then press “Set defaults” to set the interface parameters, the following message appears:
This message asks you to modify the balance’s output format so that it only sends the (net) weight to the connected PC. If you change this setting, you won’t have to modify the regular expression in 232key as shown below. However, many other balances and scales have a fixed output format which cannot be modified (you can find multiple real-life example in our support forum). To simulate this problem, we’re keeping the balance set to output format 1 (default setting). As we’re about to see, this output format is not ideal for use with 232key.
In the output tab, we instruct 232key to press the enter key after typing the weight (clearly separating the captured values as they’re being typed):
If we now place an object on the balance, switch to an application like Notepad and press the print key, 232key types not just the weight, but 3 values, e.g.:
108.6 1 108.6
Weighing a second object leads to the following output:
83.0 2 191.6
A look at the event log in 232key reveals the problem with output format 1: The scale does not only send the weight over the interface, but also the number of accumulations and the total accumulated weight, each in a separate line. 232key captures and types all of these values (as it has no way of knowing which value you’re interested in). This is indicated by the characters in blue in the event log (note how they correspond to the output above):
Capturing the right value
To make sure that 232key only captures the weight from the first line and nothing else, we have to find out what makes this line unique. One candidate would be the unit (“g”), but unfortunately it also appears on the third line:
GS 108.6 g
Total. 108.6 g
However, only the first line starts with “GS” (which – according to the user manual – stands for “gross weight”). Therefore, we have to make sure that 232key only matches lines starting with “GS”. To do so, we go to the input tab and click on “Customize…”. This brings up a dialog which lets us modify the regular expression associated with this device:
The regular expression shown above captures the first (decimal) number it encounters. You don’t have to fully understand it, it’s sufficient to add “GS” in front of it to make sure 232key only matches lines where these characters appear before the desired value:
When weighing the same two objects again, 232key now only captures the weight from the data sent by the balance (as highlighted in blue in the event log):
In many cases, it’s really that easy to prevent 232key from capturing too many values. All you have to do is find out what makes the line containing the desired value(s) unique and modify the regular expression accordingly. However, as discussed below, sometimes things can get a bit more complicated.
White space and negative values
The space characters sent by the balance after “GS” are currently being matched by the “\s*” expression inside the parentheses. (“\s*” means “match a whitespace character between zero and unlimited times”):
If the balance were to send a negative value, the fact that “\s*” appears after “[-+]” in the regular expression could become a problem. This depends on the position of the minus sign in the data sent by the balance:
“GS– 108.6 g” would be matched,
“GS –108.6 g” would not.
If you encounter this kind of problem, add another “\s*” right after the characters you’ve added before:
The regular expression above instructs 232key to look for “GS” and white space characters (between zero and unlimited times) ahead of the weight (and ahead of a potential minus or plus sign). Do we need it for the Adam Highland balance used in this example? We can’t say, because unfortunately it refused to send (“print”) any negative weights at all. For the following examples, we’ll be reverting to our previous regular expression.
Alternations and capture groups
There’s something else we did not consider: Remember that “GS” stands for gross weight? What happens if we tare a container, place an object inside and then press the print key? 232key does not type anything! A look at the event log reveals that the scale sent “NT” for net weight instead of “GS”. As this does not match our regular expression, 232key ignores the entire line:
This can be fixed by using an alternation that matches either “GS” or “NT”:
However, testing this new expression shows that we’ve made things worse. Not only did 232key not type anything, the event log also contains several error messages:
We forgot to consider that 232key will always capture and process the data from the first capture group only. A capture group is marked by round parentheses and we’ve just inadvertently added a new one which captures either “GS” or “NT”. 232key then tried to convert these characters into a number, which obviously had to fail.
The solution is to mark it as a non-capturing group by adding “?:” as the first characters inside the parentheses. This means that the group is used for matching, but not for capturing data:
Testing this expression shows that 232key now works as expected and also captures the net weight:
This article describes how you can capture the weight from a weighing instrument with differentiated digits using 232key Plus.
What are differentiated digits (a.k.a. an “auxiliary indicating device”)?
When looking at the display of an approved class I or class II weighing instrument, you might notice that one or more digits are visually differentiated from the others:
This is supposed to remind the user that on these instruments, the actual scale interval (d) is a multiple of the verification scale interval (e). For the scale shown above, e is 0.1 g and d is 0.01 g. Since e is used to determine the maximum permissible error, we can consider the differentiated digit(s) to be less accurate (but that’s not the topic of this article).
How to use 232key to capture differentiated digits
Some scales do not only visually differentiate the last digit(s), they also use a separator when transmitting them to a PC (or a printer). Instead of receiving a string like “250.01”, the software running on the PC would receive something like “250.0/1” or maybe “250.0”.
As far as our virtual keyboard wedge software 232key is concerned, this additional separating character will prevent it from capturing the entire weight value. Instead, it would only capture “250.0” (highlighted in blue in 232key’s event log):
1. Modify the regular expression to ensure all required characters are captured
Let’s continue using “/” (slash) as a separator for this example. By default, most device profiles in 232key are meant to capture numbers and therefore 232key will stop capturing when it encounters the first non-numeric character. We have to change this behavior to make sure that 232key captures the digits preceding the separator, the separator itself and the following digit(s).
To do so, we first select the device profile we want to use (we’ll go with “Generic measurement instrument” in this example), and then click on the “Customize…” button to open the regular expression dialog:
The current regular expression captures the first number it encounters (which can be positive or negative and have a dot or comma as a decimal separator):
By expanding it as below we can instruct 232key to match a slash (“/”) and the following digits, too:
Depending on the selected device profile, the regular expression shown in the dialog might look different. What’s important is that it has to be expanded to include the separator and the differentiated digits.
2. Remove the separator
Thanks to the modified regular expression, 232key is now able to capture the entire value sent from the scale, including the separator. However, it would then either show a number format error (if we’ve selected a numeric device in the input tab) or type the data including the separator into the target application (if we’ve selected a text device). Both of these outcomes are not desirable.
Therefore, we also have to instruct 232key to remove the separator from the captured data by going to the “Process” tab and entering it in the “Remove” text field:
Once this second step is completed, 232key handles differentiated digits correctly: When the scale sends “250.0/1”, 232key types “250.01” into the target application (e.g. a spreadsheet):
Obviously, you might have to adapt these instructions to match the separator sent by your scale. As mentioned, you’ll also need a paid 232key Plus license to enable the functionality shown in this article. Please don’t hesitate to contact us should you need a trial license. For assistance, please email us or post in our support forum.
232key version 2016.2.3 comes with the ability to ignore consecutive duplicates. This means that you can instruct 232key to ignore identical data captured several times in a row. I’ll explain this new feature with two usage examples.
Usage example 1: Manually transferring the weight from a scale
Let’s say that you’ve set up 232key to capture the weight from a scale and type it into a parcel processing software running on a PC. To send the weight from the scale, the user presses the “Print” button on the scale’s indicator:
Everything works fine, except that sometimes the button is inadvertently pressed twice, generating two parcel labels. You can use 232key’s new feature to prevent this from happening by checking the “ignore consecutive duplicates” option: The new ignore function will prevent the second weight from being typed. However, sometimes you might actually encounter two parcels with the same weight in a row. The second parcel would now be ignored by 232key. To fix this, click on the “Adjust…” button and enter a time limit (in milliseconds, e.g. “3000” for 3 seconds):
Any data received after the indicated time has passed is no longer ignored. Each new captured value resets the timer.
Usage example 2: Using auto print mode
In auto print mode, a scale sends the weight automatically without requiring the user to press a button. Not all scales are equipped with this mode and not all auto print modes work in the same way. The Ohaus T31P indicator used in our example has a very simple auto-print mode: It sends every stable weight to the connected PC. This can cause issues if the weight of an item fluctuates between two values: The scale might send these values several times for as long as the item remains on the platform (e.g. 20.00 and 20.05 [kg]).
This is where the second setting in the “ignore consecutive duplicates” dialog comes into play: By defining a tolerance, 232key ignores a range of values. For our example, we’d enter a tolerance of ±0.05: Now, when the scales sends a weight of 20.05 after just having sent 20.00, it is considered a duplicate and is not typed by 232key.
The tolerance setting is only available if you’ve selected a numeric device in the “input” tab. It doesn’t make sense to apply a tolerance to text devices, e.g. barcodes received from a barcode reader.
If data is captured by 232key, it becomes the new reference for both the tolerance and timeout setting even if it is ignored (unless it’s empty, i.e. it contains no printable characters). For our second example with a tolerance setting of 0.05, this means that a value of 20.00 (received first) would be typed, but 20.05 (second) and also 20.10 (third) would be ignored (20.05 + 0.05 = 20.10).
We recommend that you set a timeout in addition to the tolerance setting to restrict the ignore function (but you don’t have to).
The new ignore function is not meant to be used with scales working in continuous mode (continuously transferring data several times per second).
The first thing you’ll notice in the new version is that the tabs have been renamed and that a new tab has been added:
Input: This used to be the “Interface” tab. It lets you specify from where 232key receives its input, i.e. from which device connected to which interface. Eventually, this tab will also include an option to capture data using custom regular expressions (planned for version 1.7) and further interface options (TCP/IP and possibly USB HID in addition to RS-232/COM port).
Convert: Here, you can tell 232key to convert the data captured from the connected device. A new operation allows you to remove (or keep) the first (or last) x characters, which can be useful if your device sends additional data which you do not want to keep. The multiplication, division and rounding operations which used to appear in the “Format” tab can also be found here. All of these operations are optional, therefore you can ignore the entire tab if no conversion is required.
Output: This tab contains all settings related to the simulated keyboard (and sound) output (e.g. keyboard type, additional keys to be sent before or after the data). These are the settings from the “Format” tab which were not moved to the “Convert” tab.
We hope that the reorganized tabs make working with 232key easier even as we keep adding new features. We’re now going to run extensive tests to ensure that our software works as reliably as ever. We look forward to releasing 232key version 1.60 in the coming week.
The first stage of our website relaunch has been completed, all content from our old corporate website is now available here. The new website is based on the popular WordPress CMS and will hopefully allow us to make more frequent updates. We’ve also taken this opportunity to switch over to HTTPS (secure connection).
Download our free RS-232 software June 26, 2104 – updated March 9, 2015 Make any device with an RS-232 interface (like a scale, balance or serial bar code scanner) talk to any application on your PC using our free software 232key. Also works with devices which appear as a virtual COM port when connected to your computer.
Visit our digital scales blog Nov 11, 2013 DigitalScalesBlog.com is our latest attempt to present scales and balances in an interesting and perhaps even entertaining way (it’s in English, too).