CAN in Automation (CiA) has released the CiA 402-5 specification. It defines a new mapping for Process Data Objects (PDO) suitable for CANopen devices that are able to control asynchronous as well as synchronous motors. This takes into account that suppliers integrate position control and sequence control into the same unit.
TRADITIONALLY, SERVO AMPLIFIERS AND SYNCHRONOUS MOTORS were used for positioning applications, while frequency inverters and asynchronous motors were applied for speed-variable movements. Due to increasingly powerful micro-controllers and requirements towards higher functionality and dynamics, nowadays frequency inverters virtually have the same characteristics as servo amplifiers. That means: In a large field both device types of drives have grown closer together. That is why CiA members have specified an additional PDO mapping that covers controlling of synchronous and asynchronous motors with the very same drive.
For the user this is not only convenient but also avoids the need of two different sets of PDOs. The first PDO is used to control the CiA 402 state machine and to confirm the state change request.
The second PDO additionally contains the target position respectively the current position, and the third provides the target velocity or the current velocity. All these PDOs are predefined. This means that the CAN identifiers are assigned automatically depending on the setting of the device’s node-ID.
Even if both types of motion controllers have grown closer together, there is a need for synchronous and asynchronous motors to exist in parallel. Schneider Electric will introduce drives supporting the CiA 402-5 PDO mapping in the middle of this year. The first version will support asynchronous motors. At the end of this year, this product will also be able to control synchronous motors in velocity mode. Drives featuring a positioning mode as well are planned for next year. This mode will be available for both synchronous as well as asynchronous motors.
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