2007 tether and program cable question

[Japper]

Can anyone tell me if the pin outs of the 2007 tether and program cable are such that I can connect these two cables together to form a longer tether cable without harming the OI or the RC units?

Please advise

Thank you

[Alan Anderson]

What you want to do is perfectly okay.

You need the special tether cable between the OI and RC, but you can use extension cables on either end. The "program cable" is such an extension cable.

[whytheheckme]

Yeah, making a long extention cable isn't a bad idea... If you find the pinout for the tether and make a long tether, that's all you can use it for. If you make a long extention, you can stick a red tether cable on the end and use it as that, but you can also use it as a programming cable without the red tether cable attached.

Jacob

[AdamHeard]

Yeah, making a long extention cable isn't a bad idea... If you find the pinout for the tether and make a long tether, that's all you can use it for. If you make a long extention, you can stick a red tether cable on the end and use it as that, but you can also use it as a programming cable without the red tether cable attached.

Jacob

Sandragg of 696 has some nice 25 and 50 ft cables that work for both programmer and as a tether extension.

[Phalanx]

The tether cable is a straight through DB-9 cable. I continuity tested it last season, pin 1 is pin 1 and so on.
The programming cable is a standard DB-9 serial cable.

We have purchased two 25ft DB-9 M-F cables from here to use as extensions for both the tether and programming cables.
http://www.cablewholesale.com/catalog/db9serialcables.htm

It's nice to be able to be tethered and monitor printf's from the programming port while testing and diagnosing code.

[vhcook]

Based on our team's experience, it's also a good idea to have a short sacrificial cable off the tether port that is not screwed down. Our rookie season, we had a robot runaway on tether, and nearly ripped the tether port off the RC when the OI carriers failed to keep up.

This year, we used a short bit of ribbon cable with serial connectors on both ends, and ty-wrapped the ribbon cable down to the electronics board on the robot to make sure the cable would take the strain, rather than the RC, if we had a similar problem. (We also improved our programming to reduce the likelihood of the robot going rogue on us :o )

[Alan Anderson]

...we used a short bit of ribbon cable with serial connectors on both ends,...

That's a reasonable idea, but take care when doing this. The tether connection supplies power to the OI, and can fry the wire if your ribbon cable isn't up to the task. The year before I came on board with the team, the robot had extensions on the tether and programming connectors so they would be easily accessible. At some point when testing it out in the off-season, the OI pulled a little too much current and melted the insulation off one edge of the cable. I now know exactly which pin carries the power. :p

[artdutra04]

The program cables and program cables have exactly the same wiring; the only difference is that the tether is a female<>female cable, and the program/radio cables are male<>female cables. All you need to do to extend either the tether or program cable is to just add another program cable onto it - no modifications necessary.

[whytheheckme]

The program cables and program cables have exactly the same wiring; the only difference is that the tether is a female<>female cable, and the program/radio cables are male<>female cables. All you need to do to extend either the tether or program cable is to just add another program cable onto it - no modifications necessary.

I'm pretty sure that the tether cable reverses the Tx and Rx lines... But I could be wrong. But you are right in the sense the the program cable is simply an extension cable... and can be added to the tether cable with no effect.

Jacob

[Qbranch]

As far as I know the teather cable is just a Null Modem DB-9 Cable (http://http://en.wikipedia.org/wiki/Null_modem)... meaning, yes, the TX and RX lines are switched along with (I believe) the carrier detect and ready to send lines.

always seems like I get to the point of getting my scope out before I figure out I just have a non-crossover cable where i need a crossover or vice versa... :rolleyes:

-q

[Dave Flowerday]

But I could be wrong.
Yup, you're wrong - it is straight through. A simple gender changer on the end of a regular serial cable will convert it into a tether - we do this all the time.

[Phalanx]

Based on our team's experience, it's also a good idea to have a short sacrificial cable off the tether port that is not screwed down. Our rookie season, we had a robot runaway on tether, and nearly ripped the tether port off the RC when the OI carriers failed to keep up.


What we have done is screw in only on end of the tether or programming cables, then connect the other end to these long 25ft cables, but DO NOT SCREW THE EXTENSIONS and the Tether/Programming cable ends together. So if the robot runs away the two cables pull apart from one another without breaking the screwed in side.