[Introduction] Many engineers who work with Siemens motion controllers will hear a familiar term—DSC. What exactly is DSC? What are the advantages of DSC? How do you use DSC? Understanding these questions will give you a better grasp of the essence of Siemens motion control.
What is DSC?
In a PLC, the position loop (TO) is calculated cyclically. The update time of the position loop depends on the communication bus cycle time. Shortening the bus cycle time will inevitably increase the CPU load or affect the normal OB1 cycle time. The DSC function was developed to address this issue.
DSC (Dynamic Servo Control) is a control method that uses specific messages to move the position loop calculation and interpolation into the driver, and uses the speed of the driver to control the clock, thereby improving the positioning quality and performance.
This feature is particularly well-suited for critical servo control tasks such as high-dynamic and complex motion.
Benefits of DSC
Without DSC (Dynamic Stability Control) functionality, the long position control cycle can cause a step change in the speed setpoint, resulting in significant torque or current ripples. (See the diagram below.)
When the DSC function is activated, the position loop calculation is moved to the driver, which greatly shortens the calculation cycle and reduces torque or current ripple.
Using the DSC (Dynamic Servo Control) function offers the following benefits:
① The position controller is in the speed control loop period (e.g., 125μs or 250μs). The shorter the period, the greater the bandwidth of the system.
② It has a higher position controller gain factor Kv, so the driver with high dynamic performance can make a reference response to the set value faster.
③ It has strong dynamic anti-interference ability and can quickly suppress disturbances in mechanical rigid systems.
④ The load on the controller can be reduced by using a longer motion control cycle time.
How to use DSC
To use the DSC function, the following conditions must be met:
① The DSC only supports the following PROFIdrive messages: standard message 5 or 6 and SIEMENS message 105 or 106.
② Both the controller and the driver must support this function, such as using S7-1500 and V90PN or using SIMOTION and S120.
③ When PROFINETIRT or PROFIBUS functions need to be activated.
