RobotC is great and I want to use it and the Lego NXT to attach Robotis AX12 servos. To do this I need to access the RS485 port on the NXT port 4. Does RobotC have support code for this function?

Many thanks

As far as I know, there is no programming solution that supports the RS485 port at present. RobotC does not currently provide access to the RS485 port. It's under consideration for 2007 development.

I looked up the AX servos and they have a TTL signal level. You probably meant the DX series of servos which have RS485 outputs. They are three times as expensive. The price I saw was almost $200 US each. See http://www.tribotix.com/Products/Roboti ... alogue.htm. Are these the servos you want to use?

You might want to consider alternatives. For example, use standard NXT motors with their encoders. There are a couple of solutions for expanding the number of NXT motors supported. Would NXT motors fit your application?

Thanks for the reply Dick.

I have a Bioloid kit, containing 18 AX servos as well as a Lego NXT (with 5 motors & mux card) and want to connect the servos to the much better development environment of robotC & NXT. The TTL signal bus is proprietry using a half duplex protocol and it would be much simpler to use a serial port than have to program bit transfers on a single I/O line. Also the AX can run at upto 1 mbps. But hey ho I guess that's my route now, unless I can hack into the Bluetooth port that you support.

An alternative may be to add a ZigBee to the NXT as I can get one to fit the Bioloid.

As I want to add better audio and maybe video in the future it may be best to wait until the Blackfin Handyboard becomes available. Are you planning to support this with robotC?

Thanks again

When, and if, RS486 support is added it will include a low level mode where you are totally responsible for the protocol. The interface will allow you to read and write individual bytes onto the link with any protocol the responsibility of the application program.
If you can somehow get your servos to talk RS-485 you might be able to go this route.
Another approach to look at, if you're someone who has the skills is to use a PIC or similar micro as a protocol converter. One side would talk I2C to the NXT and the other side the proprietary servo protocol. I suspect this type of program would be under 500 lines of code on a PIC.

Hi Dick,
Is there any news about RS-485 support in RobotC firmware?
The last post was months ago, I thought maybe there is some development.
I am considering moving to RobotC from std firmware anyway, but RS485 support will make me move immediately.

Thanks
Yuval