Rockwell Automation 1404-M4_M5_M6_M8 Powermonitor 3000 User Manual, PRIOR to Firmware rev. 3.0 - Manual (Page 79)

Publication 1404-UM001D-EN-E - October 2004
Communications 4-19
• Record identifier: The Powermonitor 3000 assigns event log
records, oscillography and transient captures and other items
unique identification numbers. These numbers typically begin at
0, increment by 1 each time a new record is created, and roll
over to 0 once they reach their maximum value, typically 32,767.
The data client may use the record identifier to associate records
in different data tables or to ensure that subsequent reads
contain fresh data.
• DeviceNet unique write identifier: The DeviceNet
communications port on Powermonitor 3000 models so
equipped will discard duplicate identical messages. For that
reason, read-back selection tables include a DeviceNet unique
write identifier element. The data client changes (usually,
increments) the value of this element each time it writes an
otherwise identical message.
Writing Data to Data Tables
The Powermonitor 3000 contains a number of writeable data tables.
These tables have read/write access, so a client may read their current
content or write new content.
A valid write to a data table must meet the following general criteria:
• The length of the source data array must equal the data table
length. Note that the same data table may have a different length
in various Powermonitor 3000 models
• The entire data table must be written in one pass
• The first element in the source data array must generally contain
the correct password (or a value of -1 for read-back data
selection)
• The source and destination data type must match, e.g. floating
point or integer
• Each element of the source data array must be within the legal
range listed in the data table specification
• Reserved elements must be the correct value, usually 0
• For DeviceNet optional communications only, each consecutive
write must be unique.
You may read the Write Error Status table after writing to a data table
to verify that the write was valid and accepted by the Powermonitor
3000. If there was an error in the last write, the Write Error Status will
indicate the CSP file or assembly instance (DeviceNet only) number
and the offending element number.