Applied Motion RS-232 - Manual (Page 240)

240 920-0002 Rev. I
2/2013
Host Command Reference
Appendix A: Non-Volatile Memory in Q drives
The non-volatile memory in Q drives is partitioned into 16 sections. The partitions are dedicated to various
elements of a Q drive’s data, and are designated as follows:
Partition 1 .......................... Q Program Segment 1
Partition 2 .......................... Segment 2
Partition 3 .......................... Segment 3
Partition 4 .......................... Segment 4
Partition 5 .......................... Segment 5
Partition 6 .......................... Segment 6
Partition 7 .......................... Segment 7
Partition 8 .......................... Segment 8
Partition 9 .......................... Segment 9
Partition 10 ........................ Segment 10
Partition 11 ........................ Segment 11
Partition 12 ........................ Segment 12
Partition 13 ........................ Drive Parameters
Partition 14 ........................ Alarm History
Partition 15 ........................ NV Data Register Storage Locations 1-100
Partition 16 ........................ RESERVED
The separation of these partitions is important in understanding how the drive writes to non-volatile memory.
For example, each time the SA command is executed by the drive, all of the Drive Parameters are re-written to
non-volatile memory partition 13. Similarly, each time an RW command is executed by the drive, all of the one
hundred NV Data Register Storage Locations are re-written in partition 15, even if only one of the locations is
being updated with a new data register value.
The significance of these operations becomes clear when we consider that the physical non-volatile memory
of the Q drive is limited to approximately 10,000 write cycles. This means that after writing to any one of the 16
partitions 10,000 times, the integrity of the data stored in that memory partition cannot be insured.
For this reason, it is not recommended to use the RW or SA commands in stored Q programs. For example,
it might be tempting for a user to include an RW command or two in a stored program in such a manner that
allows for various data register values to be written to non-volatile memory on a regular basis. The temptation
of this is that there won’t be a need to reload register values manually in the case of a power down/up cycle: the
register values can simply be loaded back into the program (using RR commands) from non-volatile memory. This
is to be avoided, though, because using the RW command (or SA command) in this manner could result in the
early failure of the non-volatile memory of the drive. The intended use of the RW command therefore is to be used
in the early stages of an application, during startup and programming, to set up a series of non-volatile register
locations that can be read into a stored program using the RR command.
The partitions designated for Q Program Segment storage are typically not going to be re-written in a
manner similar to the RW and SA commands, as they are only accessed during program/segment downloads
during startup and programming of an application.