Installation guide

Estimating Network Performance
890 USE 100 00
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Step 4 At the end of the ladder logic scan in unit A, the incoming transac-
tions are handled. The transaction is complete at the next solve time
of the MSTR function in unit A. Data registers will be written, and
the MSTR function’s COMPLETE output goes ON.
The time required to process the complete communication would be:
Event T ime Range Average T ime W orst Case Time
1 0 ... 1 token rotation 1/2 token rotation 1 token rotation
2 0 ... 1 scan, unit B 1/2 scan, unit B 1 scan, unit B
3 0 ... 1 token rotation 1/2 token rotation 1 token rotation
4 0 ... 2 scans, unit A 1 scan, unit A 2 scans, unit A
If the scan time in unit B is much shorter than the token rotation time,
unit B can create the data response and have it ready before the token
reaches unit B’s peer processor. On the other hand, if a Data Slave
path is not free in unit B, the request will be queued by that unit’s peer
processor and will wait until a Data Slave path is free.
The frame format of ModbusPlus messages and the timing elements
within transactions are described in detail in Appendix A.