SBL2360 configuration problem

Hi Friends.
May you help me please?
I have one sbl2360  and two bldc motor with 12 polse, 3000 rpm, and hall sensor. 
I configured sbl2360 using Roborun+ with the closed loop speed.
Then I  made the Disable watchdog,  the inverted RS232 115200.
After that I sent "!G 1 500 (speed value)" from roborun, Motor run. But when I changed speed value, motor did not changed speed, It seemed to keep speed.
And more, I sent "!G 1 0", Motor still kept run, not stopped.

So Do you know what is my problem? how can I fix it?
Thank you so much.

Hello~
Thank you for your reply.
My problem was resolved. I connected using USB.
My problem related to PID parameter, when I changed it, It could run well.