Arduino with RS232 connection

This might be a silly question but if it is so important and so old, why not just build another one with modern technology ? Now you can get so much stuff cheap from China that wasn't available when that thing was built.

why not just build another one with modern technology ?

I wondered the same but figured the magic was the PC software which they were trying to keep running. Which is why I suggested detailing out the hardware requirements... to clone as much or as little is necessary to keep the software happy! You know, some folks still use DOS!


You know, some folks still use DOS!

The Naval shipyard at Bremerton ,Washington, USA still uses vacuum tube flip-flops in their machine shop. (since WWII)

pulper: What I would like to do is the following:

Connect the hand grip through the already attached RS232 cable to the Arduino Uno. Have the Uno convert the analog hand grip readings (as the hand grip is being used) to digital, and then communicate that directly to a computer attached to the Uno.

This brings me right back to my query about the Thread title. I wonder if you are confusing things. Within your black-box the A/D converter converts the analog force measurements to digital values. From that point on they are digital, not analog. While you can use connectors that look like RS232 hardware to carry any sort of electrical signal if the connector works when plugged into an old style PC then the data on the wires is digital.

If you are having problems with your black-box (I think you said so) the easiest thing might be to connect the Arduino direct to the A/D converter and ignore the RS232 stuff altogether. And I think someone else has hinted at the possibility of bypassing the A/D converter in the black-box and just using the A/D converter within the Arduino.


I got the impression the designer just used a sensor , an ADC , a UART /USART and it is always transmitting the digital value coming out of the ADC going into the parallel to serial USART/UART.

i've changed the title. hopefully it helps.

my goal is to have the uno replace the black box completely. hand grip connected to uno, uno then connected to computer.

i wished it was as simple as purchasing something to do this. unfortunately it isn't. anything that accomplishes what my friend wants is part of a full system and costs thousands. individually, a hand grip that interfaces with a computer to store the data isn't available as far as we know.

schematics for the hand grip aren't available. I believe it's proprietary.

the current software that is being used will be used as a template for future design, on which i'm sure it will be interesting to complete following figuring out some of the hardware essentials. won't be easy of course but then again nothing worthwhile ever is.

i was just told that there is also an "amplifier" in the black box b/c i believe the values from the hand grip are too low. that is how it was explained to me. beyond that, i don't believe there is any intelligence. It is simply taking analog values, converting them to digital, and then transmitting them to the computer software. What I'll do is play around with an old computer on which I have an RS232 to see what I can find out about the black box (my laptop does not have an RS232 port). I'll also see about trying to take apart the black box to see what I (with my limited knowledge) can figure out. If I see labels, then i'll make notes of those.

I am not sure if the PC software is receive only. I do know that you can set the baud rate and also you calibrate the analog readings from the hand grip to the software, but i think that is all internal and does not impact the black box.


you mentioned that the hand grip started out as not digital, correct? When the rs232 connector was added to the hand grip was anything else added? I'm wondering if the rs232 cable is sending serial data to the magic box and not just analog voltages. If it is just voltages the Uno can read in the voltages, (as long as they are under 5 volts) and print them to your computer using the usb cable.

then again i could be completely wrong.

Hi, thanks for clarifying the situation. Now, from this I understand, you have a DEVICE which the hand piece connects to and then the DEVICE uses RS232 to communicate with a PC. 1, The DEVICE still works. 2. The problem is interfacing it with PC which has no RS232 connector.

Will the software that communicates with the DEVICE work on the newer PC? If yes, why don't you use a RS232 to USB cable and use the COM port that will appear in the device manager?

RS232 to USB cables are cheaper than an arduino and there is no mods to be done to the DEVICE or cables?

I suppose it will rely on the ability of the software to select com ports, especially when windows tries to put usb to RS232 device at astronomical COM numbers.

Its seems to me it all relies on the PC software, no matter how you want to interface the DEVICE to the PC it has to appear to the software as a COM port.

Tom.... :)

If yes, why don't you use a RS232 to USB cable and use the COM port that will appear in the device manager?

I linked one back in Reply#1

Hi, raschemmel. Great minds think alike.... (although at times mine has a slower baudrate)

Tom..... :)

Thanks to all the posts. I did mention previously:

"A few things have happened since then and recently. RS232 ports on computers have become rarer and rarer, RS232 to USB converters are very hit and miss (at least with what we are using currently) with almost all of them being "miss", and most importantly, the box is failing and the company that built it is out of business."

However, it's a long thread here :-) and i appreciate people thinking of suggestions outside of the box (pun intended). I know the box is working intermittently (which is not good), and i will see if i can get it to give some output on my old XP computer, but there is also an issue of expanding and being able to build additional boxes. therefore, the RS232 to USB converter, while cheap and quick, is not the answer here. My friend was able to find one (after many failures) that worked:

What I've been told is that one of the issues with these types of cables is that the drivers are not updated for Windows 7 and especially Windows 8, or that Windows 7 or 8 doesn't recognize a lot of them. As time passes and newer Windows come out, this I believe is going to happen even more for the few that work with current Windows. Nevertheless, the thought of building additional units down the road is important here, as well as the challenge.:-).

In response to the post from mschramm, that would be cool if it is that simple. I think once i get my hands on the RS232 shield and play around with it for (probably) a long while, hopefully i'll find out.

thanks again to all those helping here. I appreciate the suggestions. Sorry if new info comes out from me as i'm posting about this process - i don't always know what to post until someone asks.

I don't know about that. You are certainly more popular , with a ( karma/postcount)*100=2.31, while mine is only (35/3643)*100=1.24. In fact , compared to you I must a real jerk ..... XD

@pulper, you don't seem to be using the information you are receiving here to narrow the focus of your project. In Reply #30 it all seems just as wooly as it was at the start.

As I see it you have been presented with 3 principal options 1 connect the existing RS232 to the Arduino using a suitable interface such as a Max232 chip 2 bypass the existing RS232 and connect the Arduino to the ADC in the black box 3 bypass the RS232 and the ADC and use the ADC within the Arduino

It's up to you to choose, and then if you need more assistance give us the relevant technical details


of course my posts are "wooly" or confused, vague, hazy, unclear, fuzzy (had to look that word up). i'm very new to this and i've admitted this on posts (and up to this, i've only posted 6 times).

i said early on that i'm looking at the RS232 shield and posted a link to one with a male DB9 and asked if that'll work. This was after the very helpful assistance of raschemmel.

my most recent post, and posts before that, were simply answering questions from people who I think are legitimately trying to help me out here. i answer their questions to the best of my knowledge but that of course is still "wooly". I'm not continuing on saying "please help me here" but simply answering them, at times providing additional "wooly" details, saying why I don't have what they're looking for or can't use some of their suggestions. I think that's the right thing to do; to answer people who are trying to help me out here, someone who is new to this and therefore "wooly".

I have done my best to be friendly here and to answer people's questions to the best of my ability. I appreciate all the help and suggestions provided to me and have said so on multiple occasions.

Can you open the black box and take a photo ?

i'll see if i can do that today. thanks.

The first thing we are looking for is the general layout. The second thing is the chip numbers. I don't see how the analog values can be transmitted via serial without a uController in there unless there is an A/D chip with serial out (I've never heard of it but it is certainly possible).

Here are some pics of the inside of the black box.

Regarding the overview pic, you’ll see the following:

  1. two RS232 ports on the right side and one RS232 port on the left side. On the right side, one RS232 port is for the hand grip cable, and the 2nd RS232 port on the right side is for another component that I’m not worrying about right now but connects in a similar way to the black box. I’ll refer to the two RS232 ports on the right side as “input RS232”, and the one on the right as “output RS232” (as that port is used to connect to the computer from the black box).
  2. The furthest board on the bottom right (partially underneath the largest board) has “regulator” on it.
  3. The two boards on the top are where the wires from the input RS232 connect to. The board on the top left is where the three wires from the input RS232 for the hand grip attaches.

I’ve looked up some of the labels to assist in writing the info below. The large board has the following that I could make out:

  1. A line driver/receiver with the following label:
  2. To the left of the above item, it has a longer semiconductor with the writing to the left of that being “Serial Data Converter”

On the top left board (where the wires from the input RS232 attach) it has an Amplifier with the following label: MC33272AP. It also has what appears to be another amplifier with the label: INA126P

In addition to the overview, I’ve attached two other photos. They are:

  1. The regulator on the far right.
  2. The top left board (where the wires from the input RS232 hand grip are attached)

I hope this helps visualize the current design. Based on this, if you can make any other suggestions as to what I might need beyond the RS232 shield and the Arduino, that would be great. Again, the plan is to connect the RS232 shield to the Arduino. The RS232 cable from the hand grip will attach to the shield, and the Arduino will be attached to the computer to read the data.


It looks like someone filed the numbers off the long chip next to the crystal and the ADM232 chip. That might be the A/D converter chip. It could also be a uprocessor. I'm afraid there is really not much there that we didn't already suspect, ie: instrumentation amplifier , op amps, RS232 converter. The presence of the crystal and a chip with the numbers filed off is telling. Someone didn't want anyone reverse engineering this box.

Hi, numbers are still on the chip, I must be using CSI monitor, zoom in and see. Will need to wipe a tissue with metholated spirit or isopropanol on it and observe as it dries off, another CSI trick.

But I agree it will probably be a PIC or something like it, programmed, sorry haven't got to CSI bit yet where they decode protected controller code.

Tom...... :) PS I do know how to get finger prints to shown up with superglue.