My scale (or balance) has a DB9 connector for RS232 serial communications. My old computer had serial ports which could accommodate RS232, but my new computer only has USB ports. I need to log data from my RS232 enabled scale to my USB enabled computer, what do I do?
Technological progress is usually viewed as a wonderful thing, as demonstrated by the lighting advances in computers. As modern computer
technology marches forward, it would seem that more and more of our older technology, which still works just fine, is getting left behind. Indeed, the computers available today have abandoned serial communications using an RS232 connection. It has been superseded by USB to the point of extinction. Everybody wants faster data flow, with greater inter-connectivity.
And so it would seem that all our investment in RS232 based equipment has been rendered useless. In fact, this is not the case.
Your new computer should have at least one USB serial connector on it, and it is actually a simple matter to get your RS232 equipped balance to talk to your USB equipped computer. Since both USB and RS232 are bidirectional serial communications, you can easily interface the two with a special adapter cable.
You can also install an RS232 serial port card in one of your computer’s expansion slots, but this can be difficult, and most likely an unnecessary exercise.
USB to RS232 adapter cables are available from most reputable scale and balance distributors and dealers, or from your local computer and electronics stores. They are also inexpensive, so they won’t break your budget.
Because USB and Rs232 have significantly different data rates, it is not possible to just change from one connector type to another — they won’t talk to each-other. To accommodate this, part of the adapter cable incorporates circuitry to control the data flow going each way. This prevents data underflows or overflows, which would bring everything to a complete stop. There are other “housekeeping” chores the circuitry manages, as well.
The great thing is many adapter cable manufacturers are able to fit this circuitry into the shell of the RS232 DB9 connector. There are no cards to install your computer, and no awkward dangling boxes. It’s a simple solution to get your balance back in action fast.
Installation is vert straightforward. You just plug the USB connector on the adapter cable into the USB connector on your
computer and plug the RS232 end into the cable from the balance. Note that standards vary as to which end of an RS232 cable should be female and which should be male. If you need it, be sure to get an appropriate gender changer when you get your USB to RS232 adapter cable.
You may also need a null modem adapter. This swaps the transmit and receive pins when using some types of equipment that don’t swap the pins internally. This is another case where there is no industry standard configuration.
Depending upon which brand adapter cable you get, and which operating system is installed on your computer, you may also need to install a special software driver. The driver is on a CD that is included with the adapter cable, and should include instructions on how to install it.
Some adapter cables don’t require the installation of a software driver if you are using a modern Windows operating system. They take advantage of the plug and play, or PnP, capabilities.
Quality varies greatly between brands of adapter cables (even though they all seem to come from China), and the most expensive one is not necessarily the best. In fact, the one that works best for me is the least expensive on I found.
There are no hard and fast rules to help you pick out the wheat from the chaff, so my recommendation is to ignore the brand names and try one that is at the more economical end of the spectrum and that comes with a software driver CD (in case you need it). The chances are very good that your first choice will work well; if it doesn’t, return it and try another.
You’ll be back in operation in no time at all.