Red and orange LED

What is it means when both red and orange LEDs
light on at the same time?

When I power on my SSC03A and operate it for a short time,
the red and orange LEDs light on at the same time.
And I can’t continue controlling servos.

(I attach two SSC03As on the same serial line)


The error is a framing error, which means that the servo controller thinks your serial commands are fundamentally corrupted. Usually, this is a result of stray pulses on the serial line, either from noise or problems with your code. Can you look at the serial line with an oscilloscope?

- Jan

Thank you. I use Zigbee as RS232 interface and
Simulink to send my code.
I think that the problem is Zigbee because
when I wire RS232, SMC03A works well.

Is there any suggestion different from reseting

Thank you for your help.

I agree that your wireless setup is probably causing the trouble, but I’ve had good luck with a couple of different wireless modules.

What ZigBee brand/model are you using? And at what baud-rate (and for that matter Pololu or MiniSSC-II mode)?

If you’re not pushing the range limits of your radios the solution may be as simple as lowering your baud rate. I’ve found that some serial radio modules can’t actually keep up with continuous data at what they claim is their maximum baud rate. They accept data at that baud rate, but what comes out the other end is not necessarily complete. Although in my experience, bytes were more likely to be dropped all together rather than come out corrupted.

Anyway, what are you planning to do with your wireless computer-controlled servos?


I don’t know what the brand/model of my Zigbee is. I may answer this question tomorrow I go to Lab.

The baudrate of Zigbee is 9600 and I use Pololu mode.
Changing the baudrate of Simulink (I can’t change the baudrate of my Zigbee)will lihgt on red and green LEDs at the same time. What this implies? Did you mean that I should lower down the baudrate of my Zigbee?

Also, when I wire Zigbee to servo controller by a null moden connector, the red and green LEDs light on.
But if I wire Zigbee to servo controller directly and start sending data, orange LED still light on and none
of data is transmitted.

Now I wire my Zigbee and servo controller by DB9’s pin5 and pin 3 in the servo controller side and, pin5 and pin2 in the Zigbee side. Only two lines are connected and I can’t read data from the servo controller (wire the third line will light onred and green LEDs). Is there any thing wrong of my wirng?

I may take pictures tomorrow to make a clear view.

I use the servo controller to implement a robotic control.

Thanks, pictures would definitely help.

9600 bps is a nice slow baud rate, so no, I don’t think you need to slow it down.

Another important thing is to make sure that Simulink is outputting serial data at the same baud-rate that your ZigBee modules are set to. I may have misunderstood your first post. Are you able to get your servos to move at all using the ZigBee modules? If the servo controller immediately shows the red and orange LEDs when you send your first wireless serial command, then a baud-rate mismatch could be the cause of your problem!

If you can’t check or find out what baud rate the ZigBee modules are set to, you can try a simple loopback test. Connect the transmit and receive pins of your remote module (disconnect the servo controller first) and try sending some characters to the local ZigBee modules with a terminal program. If the terminal program and the local ZigBee module are set to the same baud rate, you should receive back the same characters you type. If the baud rates are set differently, you will see different characters, garbage, or nothing at all.

Aside from the baud rate, it is important that your ZigBee modules are using the serial protocol (8N1) that the servo controller expects. If you don’t have the hardware to change the settings of your ZigBee modules, they’re probably both still set to the factory defaults, which should be listed in the manual. It is possible that the remote ZigBee module is set to a different baud rate, but this shouldn’t matter, since the servo controller can auto-detect a range of baud rates.

Hope this helps!


Baudrate of simulink and Zigbee are the same. Red and orange LEDs light on randomly. Servo controller might work
for several minutes and suddenly the LEDs light on.

Your information is useful, I will check my device tomorrow and come back.