Is there an Arduino product that supports both USB and RS-232? I need to interface to a system via RS-232, extract and save data (datalog) and upload collected data to a PC via USB. I suppose I could go with a wireless approach to the PC but not all users will have a functioning wireless configuration. Just about everyone has functional USB. I scanned the list of boards that I could find and didn't see such a device.
Do a Google search for "rs232 to ttl converter".
If you need hardware control lines the include "cts rts" in the search.
If buying from a reputable supplier, an USB FTDI based converter is a good choice. If buying from Ebay pick anything except FTDI as most cheap converters are fakes and may have problems in the future.
Need 2 solutions.
RS232 to TTL (RS232 to Arduino)
http://www.nkcelectronics.com/rs232-to-ttl-converter-board-33v232335.html
or
http://www.nkcelectronics.com/RS232-to-TTL-converter-board-DTE-with-Male-DB9-33V-to-5V_p_369.html
TTL to USB (Arduino to PC)
http://www.tinyosshop.com/index.php?route=product/product&filter_name=ftdi&filter_description=true&filter_sub_category=true&page=3&product_id=186
or
Here is one of '1284P board options, with 2 hardware serial ports, and onboard RS232: onboard or offboard FTDI Module options:
http://www.crossroadsfencing.com/BobuinoRev17/
ksquared:
Is there an Arduino product that supports both USB and RS-232? I need to interface to a system via RS-232, extract and save data (datalog) and upload collected data to a PC via USB. I suppose I could go with a wireless approach to the PC but not all users will have a functioning wireless configuration. Just about everyone has functional USB. I scanned the list of boards that I could find and didn't see such a device.
You could upload the data directly to the pc with a RS232 to USB as mentioned before, unless you want some kind of portable datalogger that saves data and then you connect it to pc, but hey, I'm just guessing the purpouse of your project.
Crossroads board shown in post #2 does as mentioned.
I have several, they are great!
Hard to beat all the features it offers.
.
Thanks for the responses. Perhaps I should have been more detailed in my query - trying to fight over-verbosity 
. My device needs to send commands and receive responses via an RS-232 connection using a proprietary protocol (a UPS system) and store the data for later retrieval by a PC. The RS-232 is given as that's how I can talk to the UPS. But the USB is not. I picked USB because of its ubiquity. Wireless connections require a "bit" more savvy from the user to connect than just plugging in a cable & the guys using this are not very computer literate. Same for a LAN cable via an RJ-45. The device will be left on the UPS system for some undefined period of time. A service person will show up at some point and download the saved data. I haven't yet calculated how much storage I'll need but it shouldn't be much. If I had to guess, I'd say about 250kb a day. Probably only run for a day or two. I'll define it as a circular buffer so I'll never run out of room. I've also thought about removable flash memory but they can be lost, pins can be bent & PC has to be able to read it. I already have such a program that runs on a PC but I want to create a device that can be left on site to collect data. Power can come from a wall wart and there is plenty of power as the typical UPS is rated for 40 to 80kva. The biggest one I've worked on was 1MVA. My first thought was to use a PIC device but I've never messed with Arduino and they seem to be a cool system. I appreciate all suggestions!
You can log data to the removable SD card on Crossroad's board.
And it has an RTC.
An Arduino Micro has separate serial interfaces for the USB and the serial pins. With an appropriate RS232 converter, such as one based on a MAX232 chip, the Micro can talk to a PC and an RS232 device simultaneously. Other Arduinos have a similar capability but the Micro is almost the smallest and definitely the easiest to work with.
ksquared:
If I had to guess, I'd say about 250kb a day. Probably only run for a day or two. I'll define it as a circular buffer so I'll never run out of room.
I can't see that the particular features of an Arduino (real time response for fine control) have any particular role in this application. Why not just use a RaspberryPi ?
...R
Robin2:
I can't see that the particular features of an Arduino (real time response for fine control) have any particular role in this application. Why not just use a RaspberryPi ?...R
Well, arduino is cheaper and smaller than raspy.
mart256:
Well, arduino is cheaper and smaller than raspy.
I thought it was the other way round ?
But what do I know 
...R
mart256:
Well, Arduino is cheaper and smaller than raspy.
Only if you need only the Arduino board itself.
Once you start adding modules the situation changes - unless you stick to the dirt-cheap Chinese clones.