Rockwell Automation 1747-SN Remote I/O Scanner - Manual (Page 108)

Publication 1747-UM013B-EN-P - January 2005
A-12 Specifications
Variable Variable Description Location of Variable
TM0 Time to perform M0 file write to
enable BT appendix B
TSNo-bt Scanner Output Delay time with
BTs present. There must be an
output delay time added for
each BT buffer that is being
used since the scanner
processes only one BT enable
or disable every TSNo-bt (to
minimize the impact on discrete
I/O throughput) .
(1)
(1) When calculating BT throughput, one T
SNo-bt
is also required to handle the BT response.
see the section Determining
TSNo-bt on page
A-7
Tbtwait Equals the sum of the
throughput times for all BTs
scheduled to the same logical
rack (time waiting is queue), +
TSNo-bt (time to schedule
pending BT). If multiple BTs are
not being performed to the
same logical rack, this value
equals zero. calculated
TRIO RIO scan time without BTs see the section RIO Scan Time
Calculation (TRIO) on page
A-4
Tbtx Amount that the RIO scan time
can be increased due to BTs.
This includes the time for the
scanner to initiate the BT and
transfer the data. see the section Determining
Tbtx on page
A-8
Tadp-bt Time for the adapter to
acknowledge the BT request.
For the 1747-ASB, the manual
defines this as no more than
one (ASB) backplane scan time
and two RIO scans. However,
the two RIO scans are already
included in the above equation
so only the ASB scan time
needs to be added. adapter user manual
Tps One processor scan time may
occur before the SLC control
program detects that the DN
flag has been set or cleared Measured or estimated