Rockwell Automation 2711 PANELBUILDER SOFTWARE USER MANUAL - Manual (Page 382)

PLC Programming Considerations
Appendix A
A-18
Real time interrupt programming is another alternative.
PLCĆ5 Block Transfer Timing
In this case, the worst case time to transfer input or display data to or from
the PLC controller can be determined by the following formula:
IE + WQ + TT + TP
IE = Instruction Execution Time
WQ = Wait time in Queue
TT = Transfer Time
TP = PanelView Terminal Process Time
To determine the terminal’s worst case display update time for PLC data
resulting from an operator input, multiply the above result by two, and add
the PLC program scan time.
Instruction Execution Time (in microseconds)
Write: 310 + 11.2Q + 5.4W
Read: 250 + 11.2Q
Q = Number of Queued block transfer requests to the same I/O chassis
(terminal) with the continuous bit set.
W = Number of Transfer Words
Wait Time in Queue
This is the sum of the “transfer times” yet to occur, ahead of the subject
block transfer request to the same I/O chassis/terminal.
Transfer Time
The transfer time is the time required to actually transfer the data to or
from the terminal. This period of time starts when the read or write block
transfer instruction sets the start bit and ends when it sets the done bit. The
length of transfer time depends on whether the transfer is to/from a local
chassis or a remote chassis (such as a terminal).