Roboteq BLDC Motor Controller Serial Communication Issue

Hello, everyone.

I know there are several people out there who have succeeded with serial communication between Arduino and Roboteq.
I have been struggling for a long time now and cannot get it to work.
Please help me figure out what am I doing wrong.

Roboteq Brushless DC Motor Controller: SBL1360

Roboteq Controllers User Manual

Arduinos used: Uno, Nano, Due

RS232 to TTL Converter Modules used:

Cable configuration:

DB9 Female To PC DB15 Male To Controller
Pin 2 (RX Data) - Pin 2 (Data Out)
Pin 3 (TX Data) - Pin 3 (Data In)
Pin 5 (GND) - Pin 5 (GND)

Setting up Roboteq via Roborun+ PC Utility Console:
^RWD 0 - Disable watchdog
%EESAV - Save Configuration

?A - Read Motor Amps
!G 1 500 - Go to Speed or to Relative Position

Sample Arduino Code:

void setup() {
  // put your setup code here, to run once:

void loop() {
  // put your main code here, to run repeatedly:
  Serial.print("!G 1 500_");

Reading and writing commands using Putty Serial

  • PC -> USB to RS232 -> RS232 to BOB15 -> SBL1360 - Works
  • PC -> Arduino -> TTL to RS232 -> RS232 to USB -> PC - Works
  • Arduino -> TTL to RS232 -> RS232 to BOB15 -> SBL1360 - Does not[/li]
    I have experimented with different Arduinos, different RS232 to TTL converters and different serial communication libraries, flipped RX/TX wires, still no luck.
    Thank you in advance,