Siemens Simovert Masterdrives Compendium page 528

Communication / CBC
Notes and rules for
process-data
processing
8.4-30
♦ The least significant byte (in the case of words) or the least
significant word (in the case of double words) is always sent first.
♦ Control word 1 must always be contained in the 1st word of the
received setpoints. If control word 2 is needed, this must be in the
4th word.
♦ Bit 10 "Control of drive unit" must always be set in control word 1,
otherwise the new setpoints and control words are not accepted by
the converter.
♦ The consistency of the process data is only ensured within the
data of a CAN telegram. If more than four words are needed, they
must be split up among several CAN telegrams because only four
words can be transferred in a CAN telegram. Because the converter
scans the setpoints asynchronously to telegram transfer, it may
happen that the first CAN telegram is accepted by the current
transfer cycle whereas the second CAN telegram still originates
from the old transfer cycle. Related setpoints, therefore, should
always be transferred in the same CAN telegram. If this is not
possible due to the peculiarities of the installation, consistency can
still be ensured by means of bit 10 "Control of drive unit". To do this,
a CAN telegram is first sent in which bit 10 of the control word has
been deleted. As a result, the setpoints are no longer accepted by
the converter. All the CAN telegrams still needed are then sent.
Finally, another CAN telegram is sent in which bit 10 of the control
word has been set. As a result, all setpoints and control words are
accepted in the converter at the same time.
♦ The described process-data functions for receiving setpoints and
control words (PZD receive, PZD-receive broadcast, PZD-receive
multicast and PZD-receive cross) can be used simultaneously. The
transferred data overlap each other in the converter, i.e. the 1st
word in the CAN telegrams PZD-receive 1, PZD-receive broadcast
1, PZD-receive multicast 1 and PZD-receive cross 1 is always
interpreted in the converter as the same control word 1. The best
way of combining these possibilities depends on the concrete
application.
6SE7087-6QX70 (Version AL)
Compendium Motion Control
03.2010
Siemens AG
SIMOVERT MASTERDRIVES