Rockwell Automation 57C570 AutoMax PC3000 User Manual - Manual (Page 71)

4Ć13
For proper operation, you must terminate both ends of the remote
I/O link by using external resistors. Use an 82W resistor to terminate
each end of the remote I/O link, unless you are using any of the
early devices listed in Table 4.3. If you are using any device listed in
this table, you must install a 150W resistor at each end of the remote
I/O link.
NOTE: You only can have 16 physical devices on a remote I/O link
that is terminated with 150W resistors.
Table 4.3 Ć Early Remote I/O Link Devices That Require 150 Ω
Termination Resistors
Device Type Catalog Number Series
Adapters 1771ĆAS All dap e s
1771ĆASB A only
1771ĆDCM
o y
Miscellaneous 1771ĆAF All Miscellaneous 1771ĆAF All
4.4 Determining Remote I/O Scan Times
The remote I/O scan time is the time it takes for the scanner to
communicate with each device in the remote I/O system. These
factors affect the remote I/O scan time:
D link data communication rate
D number of enabled racks
D number of blockĆtransfer requests
You can determine the total remote I/O scan time in a remote I/O
system by this formula:
Total Remote I/O Scan Time = # of enabled racks  time per rack
(see Table 4.4)
The formula does not take into account the time required to
complete blockĆtransfer requests. This time can be calculated
separately. See section 4.4.2 for more information.