When using an Omron Servo Drive we are getting synchronization errors reported from the drive .
Our code is bascially the dc_rtai example with the API rtos being a little different. We use xenomai and use a PowerPC 1Ghz w/ RTL8168 etherlabmaster 1.5 and operate based upon a H/W interrupt from a clock that can have see ~20usec of worse case jitter. Omron in Japan currently has the drive what they report is as follows. -------- Forwarded Message -------- From: [email protected] To: Henry Bausley <[email protected]> Subject: Re: Fw: ECAT testing between PMAC and G5 Date: Wed, 29 Feb 2012 16:48:40 -0800 Henry san, I am sorry to keep you waiting. I and Nakashima-san tested the EtherCAT connectivity between OMRON servos and some EtherCAT masters including the latest PMAC. Unfortunately only PMAC had communication error. The reason would be that PMAC has the inaccurate timing in EtherCAT frames, compared to the other masters. OMRON servo, which equips 1 buffer , can not accept the inaccurate timing of the master frames. <Test result between PMAC and OMRON servos> WKC=2 was confirmed under the condition of the LRW , so Write was completed successfully but Read error occurred. This means writing MPU ->ASIC was not completed during read instruction from the master. Normally there has to be timing gaps between a master and slaves, but the EtherCAT master has functions to compensate the timing by checking into the timing of a slave. By utilizing this function, Acontis , Beckhoff , and OMRON can realize the synchronous communication with OMRON servos. PMAC also has this function , but it seems not to work well. When PMAC is connected to Yaskawa and Sanmotion who have 3 buffers, no communication error will exist. However 1 buffer slaves like OMRON showed the communication error, because of smaller margins of the inaccuracy of frame timing. The reason for OMRON to have the 1 buffer is to realize higher accurate synchronous control than 3 buffer. ------------------------ We have used Control Techniques, Sanmotion , Yaskawa, Kollmorgen , ABB, Copley w/ DC without any issues. Does any one have any ideas for either proving or disproving Omron's theory so we find a solution? Outbound scan for Spam or Virus by Barracuda at Delta Tau _______________________________________________ etherlab-users mailing list [email protected] http://lists.etherlab.org/mailman/listinfo/etherlab-users
