Rockwell Automation 1404-M4_M5_M6_M8 Powermonitor 3000 User Manual, Firmware rev. 3.0 or LATER - Manual (Page 88)

88 Publication 1404-UM001F-EN-P - November 2009
Chapter 4 Communication
Indexed Reads of Large Data Structures
Large data structures that require indexed reads are most often read
into a computer-based application that performs further processing of
the data. The power monitor parses logs, oscillograms, harmonic
analysis results, setpoint status results, and other large data structures
into individual records to be read by the client and reassembled into
the original data structure.
You may select one of two modes for indexed table reads.
•
Auto Increment - the power monitor automatically points to the
next record following each read of the specified results table
•
Manual Increment - the client specifies a record to be read
during the next read of the results table by performing a write to
the applicable read-back select table.
The client selects the read-back mode by writing to the Read-back
Mode element in the appropriate read-back select table.
The Auto-increment mode provides the highest data throughput.
In Manual Increment mode, the client must alternate writes of the
read-back select table with reads of the read-back table.
The Indexed Data Read, Manual Mode Flow Diagram shows the flow
of alternating writes and reads required for the Manual Increment
mode.
•
First, the client writes to the appropriate read-back select table
to identify the desired data block, record or channel.
For selecting a read-back record, the client may write either a
valid password or a value of -1 to the password element in the
read-back select table
•
After a short time delay, the client reads the results table, verifies
that it is the desired record and adds it into the target data
structure.
•
The client repeats steps 1 and 2 until all the desired data is read.
IMPORTANT
DeviceNet communication option supports only manual increment
mode.