Software DDA
For precise control and adjustable speed, the Software DDA will divide the command into several equal delta commands. The maximum command is 2040 pulse, so the maximum speed is : 2040 / (0.0022 * DDA) * 60 / ENCODER. For example, DDA=5, ENCODER=4000 pulse/rev.delta command = 2040/5 = 255 pulse speed = 2040/(0.0022*5) * 60/4000 = 2781 rpm Therefore it is very important to select a proper DDA value to your system

The Operating Mode
For easily developing your system, SERVO-300 board provides three operating mode: simulation mode / open loop mode / close loop mode. Please refer to MSERVO3_SET_CONTROL_MODE() command

Simulation Mode
In simulation mode, the SERVO-300 board will simulate the motion profile. This profile is generated by user?s motion commands and send the position back to host PC. The servo board will not output V-command to control motor. It is very cost-effective and efficient in the design phase. The simulation mode can be operated off-line. The user can debug and develop his software previously. And if you have the daughter board, you can also simulate the digital input/output like as a machine.

Open Loop Mode
In open loop mode, user can directly output a constant voltage to servo driver. The constant value can be set by MSERVO3_CALV() command. This mode can be used to tune the velocity loop gain or to drive the inverter. To tune velocity loop gain, user can set a small voltage for a short time. The position and velocity can be received from MSERVO3_GET_CARD (cardNo) command in a timer interrupt(~10ms).

Close Loop Mode
In close loop mode, the servo board performs the PD controller. It also executes the following function.

1. 1. Pitch error compensation
2. 2. Limit switch auto-protection
3. 3. Hardware failure detection

The Control System
The sampling time is 2.2ms for 3-Axis control system. The control loop includes a PD controller and a pitch error compensator. The gain parameter, Kp and Kd, of PD controller can be set from host PC. The pitch errors are recorded in a size 2500 table which can be set by user. The compensating pitch is 256 pulse, so the compensation range is 2500*256=640000 pulse. (about 800mm, if screw pitch=5mm, encoder=4000pulse/rev.).