
1–2 Network Layers
Publication
17706.5.16 - October 1996
The physical layer is a set of cables and interface modules that
provides a channel for communication between the nodes. A node is
a connection point onto a network, typically containing a unique
address.
When you connect a computer serially to your DH, DH+, DH-485,
or ControlNet link, the interface module acts as an interface between
the:
• DF1 link (RS-232 or RS-422-A)
• network link (DH, DH+, DH485, ControlNet link)
DF1 Link
A DF1 link provides:
• master-slave communication through a half-duplex protocol
• peer-to-peer communication through a full-duplex protocol
This manual provides information necessary to write your own
driver for an intelligent device on a DF1 link. See “Software
Layers,” on page 1–7, for the layers your software driver must
implement so that your intelligent device can talk to other DH,
DH+, DH485, or ControlNet nodes.
Network Link
These network links are available for peer-to-peer communication:
This link Connects And allows See page
DH
•PLC2, PLC3
processors
•color graphic systems
•personal computers
•host computers
•programmable
RS232/RS422 devices
up to 64 nodes
➀
1-3
DH+
•same devices as DH
•PLC5 processors
•SLC 5/04 processor
up to 64 nodes 1-5
DH485
•SLC 500 processors
•color graphic systems
•personal computers
up to 32 nodes 1-6
ControlNet
•PLC5 processors
•I/O devices
•personal computers
•operator interface devices
up to 99 nodes --------
➀
Using
bridges (e.g., 1785KA modules), you can extend the length of your DH network to contain
up to 255 nodes.
Physical Layer
DH/DH+/DH485 link
DF1 link
nodes
IBMPC XT, AT or
compatible computer
RS232 Network Interface
network link
ControlNet
link
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