Rockwell Automation 1771-QC , D17716.5.25 SER/B SERVO POS - Manual (Page 170)

Chapter 8
8Ć9
2. Calculate system values:
Program Scan Time
PS - (5ms/K word)(4 K words) = 20ms
Processor I/O Scan Time
PIO = (0.5ms/chassis)(4 chassis) = 2ms
Remote I/O Scan Time
RIO = (7ms/chassis)(4 chassis) = 28ms
3. Calculate Block Transfer Times:
Write, TW = PS + PIO + 2 (RIO) + .5 W + 13ms
= 20 + 2 + 2 (28) + .5(64) + 13ms
= 123ms
Read, TR = PS + PIO + 2 (RIO) + .5 W + 4ms
= 20 + 2 + 2 (28) + .5(6) + 4ms
= 87ms
These times apply to all four 1771-M3 controller modules. If the system
included other block transfer modules, separate calculations would be
required for each.