Allen Bradley PLC 5 I/O Adapter & Scanner

Can anyone explain about I/O Adapter and Scanner because there is a confusion.On Allen Bradley website it is stated as a I/O Adapter module while on PLC-5 manual it is stated that PLC-5 has both I/O Adapter and Scanner mode.

Does it mean PLC-5 has integrated I/O Adapter and Scanner?

Does I/O Adapter Module also use as a scanner?

You didn't mention which PLC-5, but most PLC-5 processors have multiple, configurable, communication ports. So one port could be configured as a Remote I/O scanner, controlling and communicating with multiple remote I/O chassis.

At the same time another port connected to a completely different network could be configured as Remote I/O Adapter.

The PLC-5 could act as an adapter to another scanner PLC. This could allow it to appear as Remote I/O to another PLC. While also scanning it's own Remote I/O.

OG

see if the figure in the following post helps ...

http://forums.mrplc.com/index.php?showtopic=10811&view=findpost&p=51414

there's also another figure at the bottom of Post #7 in the same thread that might be helpful ...

The PLC(processor) typically has several I/O ports that can be setup to communicate in different ways.

Most common is to setup a PLC I/O port as a scanner. The PLC will scan for devices attached to that port and then will Read&Write data to those devices.

If you have IO cards in a rack other than the rack that the PLC processor is in, that "remote rack" will have an Adapter Module. The PLC will see (or scan) this adapter module and Read&Write to it. The adapter module will pass the PLC Write&Reads to/from the IO cards in the remote rack.

As a different scenario(less common), a PLC can also have an IO port setup as an adapter rather than a scanner. In this case, that PLC Port for PLC#1 can be scanned by another PLC(#2) (with a port setup as a scanner) such that PLC#1 port looks like an adapter module to PLC#2.

An I/O Adapter module is always an adapter. Only the PLC can scan.