Rockwell Automation 1747-DCM,D17476.8 Direct Communication Module - Manual (Page 16)

Chapter 1
Overview
1–2
The Direct Communication Module is an SLC 500 family Remote I/O (RIO)
adapter. It allows supervisory processors, such as PLC–5s, and distributed
SLC–500 processors residing on an Allen–Bradley RIO Communication
Link to transfer data between each other. The DCM appears as an RIO
adapter to:
•
a PLC processor with integral RIO scanner on the RIO Communication
Link
•
an RIO scanner, Catalog Number 1771–SN or 1747–SN, on the RIO
Communication Link
RIO Scanner
PanelView t (adapter)
RIO Communication Link
DCM 1
DCM 2
DCM 3
Supervisory PLC or SLC
Distributed SLCs with
DCMs (adapters)
DCM modules are connected in a daisy–chain configuration using Belden
9463 cable.
What Is a Remote I/O Adapter?
A remote I/O adapter (RIO adapter) is any module that acts as a slave to an
RIO scanner, the master on the RIO link. The DCM is an RIO adapter.
All RIO scanners have defined physical and logical specifications. Physical
specifications are the maximum number of adapters that can be connected to
the scanner. (See Extended Node Capability on page 1–4.) Logical
specifications are the maximum number of logical racks the scanner can
address, the ways logical racks can be assigned, and the ability of the scanner
to perform block transfers. Refer to the appropriate scanner manual for
details concerning physical and logical specifications.
The DCM can physically reside on the RIO link with any other adapter. The
following table lists the adapters available for use with an RIO link.
System Overview