Dual serial motor controller (beginner has some problems)

So, I picked up one of the low-voltage dual serial motor controllers and am having some trouble making it work. I would like to run it from a Imsys SNAP controller in a Tilt400 Pro using one of the RS-232 ports, “serial0.” I wired a DB-9 pins as follows: pin 3 SERIN, pin 4 RST, pin 5 GND. Logic supply is taken from 5 volt pins on the Tilt400.

I’m able to write to “serial0” without throwning any exceptions, but I can’t get the board lights to ever come on. Sending configuration commans will not cause light to flash, nor will any regular command sequences. The motor out pins never go high when motor power is attached.

Anyone know where the problem could be?

The board I’m using it with is here:


It sounds like you are using an inverted, RS-232 signal on the logic-level inputs of your motor controller, which could potentially destroy the motor controller. If you do have RS-232-level signals, you need to connect them to the inputs at the other end of the board (they are labeled “COM” on the back of the circuit board.

- Jan

Thanks for the reply, but I’m alredy using the other set of pins.

Sorry about that; I didn’t realize the pin numbers referred to the DB9 pins. Have you verified that you are getting serial signals out of your port? An oscilloscope would be really handy for this. Also, are you sure you’re not holding the motor controller in the reset state with the handshaking line? If you look at the logic-level reset input with a meter, it should be at the logic high voltage.

- Jan