Rockwell-automation 1771-DE Absolute Encoder Module User Manual Manuale Utente Scaricare il pdf (Pagina 46)

Appendix A

AĆ5

1. Calculate the system values that are determined by the system

configuration.

Program Scan (PS) = (5 ms/1K words) x (number of program

words)

Processor I/O Scan (PIO) = (1 ms/rack number) x (number of

declared rack numbers)

Number of words transferred (W) = 2 (read) or 20 (write)

2. Calculate the block-transfer time (T) for the read or write operation.

T = 0.08 ms/word x number of words transferred

3. Calculate the worst case system time (ST) between transfers.

ST =PS + PIO + T(1)(read) + T(2)(read) +T(3)(read) +...

PS + PIO + T(1)(write) + T(2)(write) + T(3)(write) +...

=2(PS + PIO) + T(1)(read) + T(2)(read) + T(3)(read) + ...

T(1)(write) + T(2)(write) + T(3)(write) + ...

Example 2

A PLC-2/30 programmable controller is controlling four I/O racks

in a local configuration. Assume one block-transfer module per

chassis and one assigned rack number per chassis (Figure A.2).

1 2 ... 41 42 43 44 45 46 47 48 49 50 51 ... 79 80

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Rockwell-automation 1771-DE Absolute Encoder Module User Manual Manuale Utente Pagina 46