Rockwell Automation 1747-ASB Remote I/O Adapter - Manual (Page 140)

Publication 1747-UM006B-EN-P - June 2003
A-12 Specifications
6. Substitute all the values for variables in the throughput formula
and solve for throughput:
T
dm-bt
= T
dm-nbt
+ 2T
btx
T
dm-bt
= 80ms + 2(34.7)ms
T
dm-bt
= 149.4ms
Block Transfer Throughput
Block transfer throughput is always slower than discrete data transfer.
It is dependent on the time involved for the:
•
PLC control program to enable the block transfer
(1)
•
PLC to generate a request for a block transfer
(1)
•
1747-ASB module to acknowledge the request
(2)
•
PLC to initiate the block transfer
(1)
•
time involved to block transfer the data
(3)
•
1747-ASB backplane scan
(4)
As noted above, block transfer timing is PLC dependent. To calculate
block transfer throughput, refer to the applicable PLC programming
document.
(1) This is dependent on the PLC processor and scanner.
(2) Once the block transfer is request is received, the acknowledgement occurs in no more than one backplane
scan and two RIO scans.
(3) The time involved to block transfer data is calculated using the T
ri
formula in the previous section.
(4) The 1747-ASB backplane scan time is calculated in the same manner as described in the discrete throughput
sections.