Rockwell Automation 1771-ASB/E Remote I/O Adapter User Manual - Manual (Page 83)

Questions and Answers D–3
Publication 1771ĆUM001A-US-P - February 2000
Q. My remote I/O is working fine without termination resistors.
Are they really required?
A. Yes, termination resistors are required. Any change in the
RIO network installation (i.e. cable length, baud rate) can
cause a remote I/O communication failure without proper
termination. Installing termination resistors reduces the
chance of this occurring.
Q. I have an existing PLC remote I/O system that I’m replacing
with 1771. Are the new adapters compatible with the older
processors?
A. Any remote I/O adapter is compatible with any processor.
Any and all series/revisions of remote I/O adapter devices
can be mixed on the blue hose. Make sure you set the adapter
switches correctly, since switch positions may have changed
on later adapters. Also, older racks and adapters only support
2 slot addressing and 8 pt. modules, while newer racks and
adapters and racks have no such restrictions.
Q. I’m replacing an existing PLC-2 remote I/O system with
new PLC-5 processors. Will the new processors work with
the older 1771-ASB adapters?
A. Again, any processor will work with any series/revision
remote I/O adapter. Watch your switch settings. Old power
supplies can be used to power your adapters, but cannot be
used to power the rack containing a PLC-5 processor. PLC-5
processors must be powered by slot power supplies or by a
1771-P7 supply.
Q. Specifications for my processor state that it can support 24
logical racks, but it won’t accept any rack addresses over
rack 17 (16 physical racks).
A. This is a processor limitation. Each RIO channel is limited to
16 logical racks which can be scanned by the channel. The
additional racks can be scanned on another RIO channel, if
practical.
Q. How do I add a 1771-ASB adapter module to my
ControlLogix remote I/O network?
A. Simply add the adapter under the 1756-DHRIO scanner in
the Logix5550 Controller Organizer I/O configuration tree.
With the scanner, adapter and chassis switches set correctly,
download the program to the Logix5550 processor and
switch to Run mode. Communication to the adapter will
commence.