Rexroth motion control system architecture

The standard architecture includes some PPC control units (depending on the number of machine motors) connected by an optic fibre ring known as “Link Ring”. The cables are identical to the ones used to connect each PPC withthe drives of the Sercos ring. The Link Ring is used to share the master signal between the PPC’s. More specifically a PPC will be configured as the Link Ring Master (normally PPC#1) and the others as Link Ring Slaves (up to max. 32 PPC’s). PPC#1 generates a master signal through its virtual master 1 and makes it available on the Link Ring in a synchronous way. As a result all the drives, even those that are physically linked with the PPC#2….N, will receive the same master signal and all the machine motors will be perfectly synchronised.

Each PPC is connected with the machine PLC via a field bus (e.g. Profibus DP) and is its slave node. The input and output information necessary for the correct operation of the Motion Control system are exchanged via this bus (enables, product length, alarm messages, etc.). Each PPC-controlled drive group is connected with it by means of optics that form the Sercos ring. A PPC can control till to 40 drives.
Finally, a power cable (3 phases+PE+thermal pad wires) and a signal cable (feedback of the encoder on the back of the motor) connect each drive with the servomotor.