Problem about close loop speed mode - HDC 2450

I'm using HDC 2450 to control 2 DC motors(24V, 120RPM) with encoder(PPR - 1024). When I ran motors in open loop mode, they ran as well. However after configuring encoder(PPR-1024,feedback), motor speed( maxRPM-120, acceleration 60, deceleration 60 ) and keep default PID parameters, changing operating mode to closed loop speed mode, then both 2 motors dont work when I move the cursor.
what is my mistake here.

More than likely it is the loop error detection that is causing this. In the closed loop parameters, you can set this to disabled. Make sure to save to controller afterwards.

I disabled loop error detection, however motors still dont run. DOUT1 and DOUT2 are off when I try to make speed command on "run" tab. I also disabled pulse inputs and analog inputs.
Check encoder ( speed and count ) reading looks right and speed polarity is right.
What should I do now.

Since you are using the closed loop speed, try setting the following for your PID.

P=0
I=5
D=0

Your closed loops speed will use the I gain over the P gain. You may need to add some P gain (try 0.5 if needed).

I followed as you said ( 2 cases of KP ). However, nothing happen, motors still dont run.
I also set watchdog = 0 ( I saw at other topic, someone said that )
Another question, in open loop mode, I send command G,1,100 => Speed in RPM : 8 , RPM of my motor is 120. This command means that controller gives 10% power to motor. How do I know this speed in RPM is right. I feel it's right but im not sure about it.

Are there any status led faults that are currently lit red?

In terms of the speed, if your encoder PPR is set correctly, then the speed should be correct. You can verify this if you have a tachometer that you can use to measure the speed of motor.

There is a faulty led which is undervolt . However motor still works as well at open loop even if undervolt led is on. and after charging the battery and check volt of battery by multimeter , the undervolt is still on.

I think the problem may be the Speed and acceleration parameter. Since the values are so low, the time to ramp up is very slow.

My motor RPM is 120, with my application , I cant use high speed and acceleration, just around 30-50 RPM.
I see that
in open loop, motor runs , DOUT1 and DOUT2 are on
in closed loop, motors doesnt run, DOUT1 and DOUT 2 are off.

I take it maybe you are wired to the yellow power control line? You'll need to wire battery 12V recommended minimum to the thick red wires.