HSR-8498HB and serial connection: Help please!

[carloti]

Hi everyone!

I try to connect this servo to a Ubuntu PC with serial connection, using a RS232-ttl conversor.

I supply 6V (1000mA) to the servo and 3.3V to the conversor.

I am programming in C, to send package bytes I use this:
unsigned char instruct[][7] = {
{ 0x080, 0xE7, 0x00, 0x00, (256 - (0x080 + 0xE7 + 0x00 + 0x00)), 0x00, 0x00 }, /* 1){7} .getID+Version*/
{ 0x080, 0x00, 0x08, 0x34, 0xCC, 0x00, 0x00 } /* 1){7} .setPosition*/
};
I configure the channel speed at 19200.

It is curious but I achieve to move the servo one time. I dont know if the servo receive the package. I observe that the servo lock when I connect and I dont know why?

If the checksum ok? Anyone see what can be failing?

Thanks

Is the

[i-Bot]

The servo protocol does not work with a standard RS232 to serial converter. Did you use the Hitec circuit ?

http://www.robonova.de/store/support/in ... =126&nav=0

[carloti]

Thank you very much for your answear!

That could be the problem. I´m using a standard RS232 converter. The weird thing is that in some prubes, it works and the servo moves, but when you try again, it fails.

What can I do to send command through the COM port and It works??
Where can I get than serial converter??
Im trying with other servo Dinamixel ax-12 an I don´t have problems.

Thanks a lot.

[i-Bot]

A standard RS232 to TTL inverts the signal and this is not right for HMI. The occasional servo movement is probably due to there being pulses in the serial data which trigger PPM movement of the servo.

The programmer file I gave has the Hitec cable schematic under the help menu.

or it is in my file area:
http://robosavvy.com/Builders/i-Bot/HMI%20cable.PNG

There are some other HMI related docs in my file area too:
http://robosavvy.com/Builders/i-Bot/

[carloti]

The program you gave me is for Windows and I,m and doing this in Linux.

My question now is, can I invert the signal in the source code? or what I need to adapt the standard rs232 to hitec servo?

I don't know much about electric circuits.

All I have to do is with Ubuntu, and RS-232 ttl converter and hictec servo, send commands through the serial port in order to the servo response (give us ID + version, change positoin, speed, etc...)

Im out of time and for that reason I need help.
Thanks again.

[i-Bot]

No, you cannot invert the signal in source code.

Make the simple cable in the PNG file above and use that instead of the RS232 to TTL converter. Works in linux as well as Windows.

[carloti]

Finally! Success!

But now I have to connect 2 o more servos simultaneously.
I connect the servo to a breadboard. How can I plug 2 servos and send packages to move the two at the same time??

Anybody knows how?

[i-Bot]

The HMI protocol is supposed to support multiple ID's of servos on the same bus. All pins wired together. I never tried this because my humanoids had 18 servos and the slow data rate made it too slow to go around all the servos.

This gives some idea of how to set ID ( Only have one on bus a this time), then subsequently move them by ID.
http://robosavvy.com/Builders/i-Bot/HSR8498_serial.pdf