Help with linking OI and RC over Internet....

[P1d40n3]

My team is trying out an interesting project; namely, we are making a robotic hall monitor that can be controlled over the Internet. But we've hit a roadblock of sorts.

We have 2 GW21W's, one connected to the Tether port on the OI, and one to the Tether port on the RC. I know that the two are connected (their status pages say they're connected to each other), but for some reason, there is no data passing between them. What I'm thinking the problem is that the serial port on the RC GW21W is improperly configured for outputting to the RC.

So what I need to know is this (If indeed my theory is right);

The flow control scheme that the RC uses, and the bit parity. Also, if you have any ideas (pitfalls to look out for, questions, etc.) feel free to post them.

A thousand thanks to all those help us .

-commander Adam 'P1' Burch

[Tom Bottiglieri]

http://www.ifirobotics.com/radio_modem.shtml
9600bps Full Duplex. Not sure if that helps. For the bit parity, I would say just brute force it and try all of the available options.

I hope you're going to have some kind of local object detection system on the robot, or at least some kind of emergency shut-off in case of packet drop. The last thing you want is a router to shut off and your robot to slam into a person in the hall.

[Greg Marra]

Originally Posted by P1d40n3

We have 2 GW21W's, one connected to the Tether port on the OI, and one to the Tether port on the RC. I know that the two are connected (their status pages say they're connected to each other), but for some reason, there is no data passing between them. What I'm thinking the problem is that the serial port on the RC GW21W is improperly configured for outputting to the RC.

I'm not particularly familiar with the communication schemes used by the RC, but have you gotten these boxes working with other serial devices? You've probably already tried this, but if the problem lies in the GW21W instead of the RC, you could be banging your head against the wall. Try putting another serial device through them and see if that works.

[EHaskins]

If I remember right radio and possibly the tether ports are rs422 not rs232.

[divergentdave]

You may want to investigate the tether specs further, because I think that the OI might be trying to draw power from the robot through it. If your serial connectors don't supply voltage through the right pin, it might turn on some failsafe feature on the OI.

[Kevin Sevcik]

To further add to the confusion, it's possible that the tether uses characters that could confuse your adapter. It looks like COM1 will switch to a console if you send 'Z' or 'z' 3 times in a row. So I'd be safe and use COM2.

[Tristan Lall]

That serial box is available with RS-422, according to the specifications (well, one place says -422, but there are no subsequent mentions of it). You might want to ask whoever sold it to you to exchange it for the RS-422 model, to connect via the radio ports instead. With luck, the hardware would treat it identically to the E-Wave modems that we use now.

[Kevin Sevcik]

Think again, Tristan.

IFI Radio to Wifi FAQ

Modems have tons of commands that tell the modem how to connect to the other modem, etc. The RC isn't expecting to see an OI at the end of the radio port. When its setup commands aren't replied to, it just won't work. If this did work, you could just hookup the RC to OI with an RS-422 crossover cable and get much better max distance than with the tether thanks to the differential signalling.

[Astronouth7303]

Originally Posted by divergentdave

You may want to investigate the tether specs further, because I think that the OI might be trying to draw power from the robot through it. If your serial connectors don't supply voltage through the right pin, it might turn on some failsafe feature on the OI.

The OI only draws power from the RC if it isn't plugged into the wall. (Personal experience: Plugging-in OI can solve "chasing LEDs" problem.)

[P1d40n3]

Thanks for help all!

Just so we're clear, the team and P1 also plan to attach a wireless webcam to the robot, so as to get a live feed from the robot. The goal is to set it up as a hall monitor you cna use from anywhere in the world. As long as you have the right password.

[cdfps]

I read the posts and I don't fully understand what you are doing. I get the perception that you want a computer somewhere in the building and the robots f in the hall.

The last time I did this, I put a laptop on the robot, used a free timelife giveaway usb camera, a power wheels 6 wheeler, a car battery ,ran Libranet with apache, and wrote CGI in c to control the 225in/oz steppers I was using to move it.

The stepper driver kept the motors constantly hot so battery life was low.

The forward, backward, etc, etc scripts were called when a button on the web page was clicked.

The robot was a simple build and worked easily from inside the school, getting through the school firewall waws a lot harder.

I probbably have the c cgi source as well as the web pages used, and maybe some documentation. If you want I can take a look and send it along to you.

For a while I had a telerobotic tethered turtle in my office which anyone in school could access. Turns out there are two kinds of people. The kind that spin the telerobotic turtle around 5000 times to wrap up it's teather and the kind that would drive it into you.

[P1d40n3]

Originally Posted by cdfps

I probbably have the c cgi source as well as the web pages used, and maybe some documentation. If you want I can take a look and send it along to you.

That would be very nice. But how did the laptop connect to the RC? Or was the laptop acting as the RC?

The original plan was to have the Operator Interface connected to the first GW21W, and have that GW connect to the other GW via the schools WiFi. This last GW would then send the OI data to the RC. But appentally, the OI and RC use non-spec communications...

I think pairing up the OI/RC works, as long as you have a remote kill switch. Talking to the RC via serial port with those adapters is likely to work much better.

When you say the serial port, do you mean the Program port, or the TTL pin-thingies?

[Hieb]

Originally Posted by P1d40n3

When you say the serial port, do you mean the Program port, or the TTL pin-thingies?

I was refering to the 4 pin connection that the camera uses. I'm sorry I can't provide you with more detail, but when I first considered this a couple months ago it was because I stumbled across an adapter or wifi web device that I thought would work for just this application. Unfortunately I've been spending more time trying to raise money so we can compete this year and not enough playing with robots.

[Matt Krass]

Originally Posted by P1d40n3

That would be very nice. But how did the laptop connect to the RC? Or was the laptop acting as the RC?

The original plan was to have the Operator Interface connected to the first GW21W, and have that GW connect to the other GW via the schools WiFi. This last GW would then send the OI data to the RC. But appentally, the OI and RC use non-spec communications...



When you say the serial port, do you mean the Program port, or the TTL pin-thingies?

You could use either, but I was referring to the program port.

[P1d40n3]

Originally Posted by Matt Krass

You could use either, but I was referring to the program port.

Forgive my ignorance, but how on earth would you do that? Does the code even have alias' for the program port?