Rockwell Automation 1402-LSM Line Synchronization Module Installation Instructions - Manual (Page 36)

Chapter 4
Application Information
4–2
Synchronization and Monitor with Load Share
In this mode of operation, data is returned for Synchronizing Bus voltage,
current, and power values, and reference bus voltage values. The error values
and discrete inputs to the PLC–5 for synchronization and load share are
modified.
Block Transfer Communications
The LSM is capable of exchanging large amounts of data with the PLC
processor via the Block Transfer mechanism. The amount of data greatly
exceeds that which could be accommodated by a single block transfer. As a
result, the data is divided into many different “files” and can be obtained
through the use of multiple Block Transfers.
The LSM uses a unique scheme for differentiating between sets of
parameters, or “files”, being written to or read from the module. The size of
the block transfer operation is used to define the size of the transaction and is
also used as a block type ID. Each of the “files” that the LSM recognizes has
a unique size and can therefore be identified by the module. This is a very
important aspect of understanding how the LSM communicates with the
PLC–5. The size, structure, and content of the block transfer reads and writes
supported by the LSM are provided in Appendix B.
!
ATTENTION: Only one block transfer at a time may be issued
to the LSM. This means that until a BTR or BTW to the LSM has
completed, another block transfer to the LSM must not be
initiated. Failure to observe this requirement will result in
improper operation of the data exchange with the module.
Only one block transfer at a time may be issued to the LSM. This means that
until a BTR or BTW to the LSM has completed, another block transfer to the
LSM must not be initiated. Failure to observe this requirement will result in
improper operation of the data exchange with the module.
The LSM uses a modulus method of accepting and returning numbers greater
than 1000 or between 0 and 1. The modulus method splits these types of
numbers into two or more words with the range 0– 999. The modulus is
given in the form 10
6 , 10 3 , 10 0 , or 10 –3 .
For example, the number 10,000 would be represented by a 10 in the
modulus 10
3 word and a 0 in the modulus 10 0 word. The number 10.5 would
be represented by a 10 in the modulus 10 0 word and a 500 in the modulus
10 –3 word.
To process numbers received from the LSM in this format, the number in the
modulus 10
3 word must be multiplied by 1000 and added to the number in
the modulus 10 0 word.
Overview Continued
Interfacing to the LSM