Rockwell Automation 1771-DA,D17716.5.13 U MNL 1771-DA ASCII I/O MODULE User Manual
Page 174
ASCII Module
PLC-2 Family Processors
Appendix A
AĆ6
transfer instructions in the ladder diagram program during any program
scan. A block transfer module will not accept another transfer until
finished processing the previous transfer. For a worst case calculation of
the time between block transfers, assume that the number of enabled
block transfer instructions during any program scan is equal to the number
of block transfer modules in the system. Also assume that the ASCII
module is transferring 64 words in a write or read operation and 2 words
in the alternate operation. The module will toggle, when done, from one
operation to the other in the next program scan.
The method for calculating the worst case time between block transfers
will be covered for the following cases: PLC-2/30 remote and local
systems, and Mini-PLC-2/15 controller.