Hello,
Ok, I’ve wasted hours and hours trying everything possible but my vb.net app simply isn’t working.
I’ve even tried the pololu serial transmitter v1.3 utility. I send this 6 byte command:
0xAA, 0x0C, 0x04, 0x00, 0x70, 0x2E
And it gives me this response:
02:43:31 AM sent AA 0C 04 00 70 2E
received: 1E ‘’ 7C ‘|’
And the red light goes red. Weird thing is I had to click the send 6-byte button 3x before I got the status message and it did still move the servo the neutral position.
Maestro Control Center has settings setup for UART Fixed Baud Rate to 9600, the serial port was COM3. I’m using a USB to TTL converter, with the tx-rx pins connected to the tx-rx pins on the board.
I’ve also tried using the USB on the maestro and my app connecting via the virtual TTL com port.
My only guess is I have something mis configured or something.
Can someone help me… please??? I’m so frustrated 
Is your Maestro’s device number actually 12 (0xC)?
Did you connect the GND of your USB-to-TTL converter to the GND of the Maestro?
Did you connect the adapter’s TX to the Maestro’s RX?
Is there anything else connected to the adapter or the Maestro?
Did you set the baud rate of the USB-to-TTL serial adapter correctly? You have to specify a baud rate when connecting with the Pololu Serial Transmitter Utility, and it must be 9600 because that’s what your Maestro is using.
The red LED being on means that the Maestro experienced an error, so could you open up the Maestro Control Center and tell us what specific error it is?
–David
Hello David,
I think I’m making a bit of progress 
If I execute this command via serial utility to set servo 0 to 1500 position, it’s hit or miss. Sometimes it will move the servo without the red light, other times it does nothing and shows the red light (yet if I click the send byte button one or two times after the red light it will move the servo):
0x84, 0x00, 0x70, 0x2E
The red light error code is 0x0010 which means “Serial protocol error”.
Also, I’m pretty sure I read it somewhere in the manual, but is there a minimum amount of time required between commands sent via TTL?
Answers to your questions:
Is your Maestro’s device number actually 12 (0xC)?
- I have no idea, I only have one device but I can’t find anywhere where the device number is located so that was a copy/paste from the manual, I’ll be using the compact protocol
Did you connect the GND of your USB-to-TTL converter to the GND of the Maestro?
- the USB-to-TTL converter only had 4 pins: VSS, TX, RX, RES. The VIN and GND pins on the maestro are connected directly to a 12v power source
Did you connect the adapter’s TX to the Maestro’s RX?
- sure did, the TX/RX on the USB-to-TTL adapter connect to the RX/TX pins on the maestro
Is there anything else connected to the adapter or the Maestro?
- no, just one servo to servo #0 pins, and servo power to the power in on the maestro
Did you set the baud rate of the USB-to-TTL serial adapter correctly? You have to specify a baud rate when connecting with the Pololu Serial Transmitter Utility, and it must be 9600 because that’s what your Maestro is using.
- sure did, using “UART, fixed baud rate: 9600”
The red LED being on means that the Maestro experienced an error, so could you open up the Maestro Control Center and tell us what specific error it is?
Hopefully it’s an easy fix
VSS is another term for GND/ground. After checking the user’s guide of your converter to verify what VSS is, you should connect VSS to a GND pin on the Maestro. In general, all of your boards should share a common ground.
There is no amount of time that you have to wait between serial commands. You can send commands as fast as you want, as long as you are using a baud rate that isn’t too high (usually anything under 115.2 kbps is fine, but see the “Maestro Settings Limitations” section in the user’s guide for more info).
–David
Hello,
Awesome, thanks David, will give that a try.
Oh yeah… I’m on cloud 9. The ground not connected from the usb-ttl to the maestro was the issue. Now that it’s connected there is no red light turning on and she works perfectly!
Off to coding now
