SLC 500 Communications
SLC 500
COMMUNICATIONS
1
SLC 500 Communications
Requirements for
Industrial Networks

An industrial communication link


Capable of supporting real-time control
High data integrity
High noise immunity
High reliability in harsh environments

Suitable for large installations


2
SLC 500 Communications
Local Area Network - Applications
Centralized Data Monitering and Acquisition
 Manufacturing
 SCADA

MMI
Distributed Control
 Communication between programmable controllers
 Upload to a programmer or host computer from any PLC
 Download from a programmer or host computer to any PLC
 Read/write I/O values, registers of any PLC
 Monitoring of PLC status and control of PLC operation 3
SLC 500 Communications
Network Topologies
Daisy-Chain
– Each device has two sections of cable tied together
– Each end has termination (resistor/capacitor)
Examples
DH+
DH-485
Remote I/O
SLC
SLC
Beldon #9463 cable
SLC
SLC
4
SLC 500 Communications
Network Topologies
Star
– All devices physically connected at one point
Example
Ethernet
PLC
PLC
PLC
PLC
5
SLC 500 Communications
Network Topologies
Trunk-Line / Drop-Line
– Trunk line very long - run through plant
– Drop lines very short
– Drops connected to trunk with Y-adapters
Examples
Data Highway (DH)
Devicenet
DH+ can be
Trunk Line
Drop Line
SLC
Drop Line
SLC
Drop Line
SLC
Drop Line
SLC
6
SLC 500 Communications
Network Access Methods
Token Passing:
– Each node can talk on the network when it
has the token
– After done talking, the node will “Pass the
token” to the next node
– Multi-master network
– Eliminates data collisions
TOKEN
#1
#3
#2
SLC
SLC
#4
SLC
SLC
7
SLC 500 Communications
Network Access Methods
Master / Slave:
– Master talks to one slave at a time
– The slave can only talk if the master
asks it for some information
– Polling network
– Eliminates data collision
– Single master network
Network
Controller
(Master)
Request ?
#1
Reply !
SLC
(Slave)
#2
SLC
(Slave)
#3
SLC
(Slave)
#4
SLC
(Slave)
8
SLC 500 Communications
Networks - How to Decide on One?

Maximum number of devices
– How many nodes are required for the application?
– How many nodes should be reserved for future
expansion?

Maximum network length
– Usually specified as the physical cable distance from the
first node to the last node on the network
– Drop length is the length of cable from the main cable to
the node

Device supported
–
–
–
–


Programmable controllers
Programming devices
Operator Interfaces
Other Computers - PCs, Workstations, Minis, Mainframes...
Response time
Application interface
9
SLC 500 Communications
A-B Communication Network Terms
RS-232
RS-422
What the hell do
all these mean?
RS-485
DH-485
REMOTE I/O
DF1
DH+
10
SLC 500 Communications
A-B Communication Network Terms
RS-232
RS-422
RS-485
DH-485
}
Electrical Connections
}
REMOTE I/O
DF1
DH+
Protocols (languages)
Must have matching electrical connections and
protocols for two computers to communicate.
11
SLC 500 Communications
Communications - Like a Phone
Call...
12
SLC 500 Communications
Communications - Like a Phone
Call...
Electrical Connection
is made when person
answers phone
13
SLC 500 Communications
Communications - Like a Phone
Call...
Electrical Connection
is made when person
answers phone
ENGLISH
COMMS
FRENCH
14
SLC 500 Communications
Communications - Like a Phone
Call...
Electrical Connection
is made when person
answers phone
Communication when
connection make AND
both people speak the
same language
ENGLISH
COMMS
FRENCH
ENGLISH
COMMS
ENGLISH
15
SLC 500 Communications
Networks: DH-485 and DH+

Network Communications
– Program support and monitering
– Supervisory control for distributed hierarchy
– Operator interface for monitoring and control
16
SLC 500 Communications
DH-485 Characteristics

DH-485 Multi-drop link

Daisy chain configuration

Token passing system

9.6 or 19.2 Kbaud data rate

Connect up to 32 devices on network

Up to 4000 cable feet (1200 meters) of network lenght
17
SLC 500 Communications
DH485 Peer-to-peer Comms.

Send/Recv messages from other SLC 500s

Multi-master token-passing ring; 32 nodes

5/02, 5/03 + 5/04 can initiate communications to
other processors

5/03 can using Channel 0, Channel 1, or both

5/04 can using Channel 0 only

Fixed and 5/01 respond only

Initiate comms. with MESSAGE instruction in
ladder logic

NO ladder programming necessary to respond
18
to a message from another processor
SLC 500 Communications
Typical DH-485 Network
ALLEN-BRADLEY
RUN
DTAM Plus
ALARM
PIC
AIC+
SLC 5/04
Link Coupler
Link Coupler
Link Coupler
SLC 5/03
SLC 5/02
SLC 5/01
Link Coupler
SLC 500 Fixed
19
SLC 500 Communications
DH+ Characteristics
•
Peer-to-Peer Communication
– Utilizes Tolken Passing
•
•
•
•
•
•
64 nodes maximum
Remote Programming of SLC 500’S, PLC-2, PLC3, and PLC-5
Direct Connections to 5/04,PLC-5, Panelview, and
Industrial Terminals
57.6, 115.2, OR 230Kbaud data rate
Pub # 1770-6.5.16 DH/DH-485/DH+ Ref Manual
Robust Industrial Network
20
SLC 500 Communications
DH+ Communications
RSLogix 500 Software
AI 500 Software
6200/AI Software
DH+
57.6Kbaud: 10,000 feet
115.2Kbaud: 5,000 feet
230.4Kbaud: 2,500 feet
Other
Processors
SLC-5/04
PLC-5
PLC-2, PLC-3
PLC-5/250
21
SLC 500 Communications
DH+ to DH-485 Interface

Interface through a 1785-KA5
– Translate DH-485 <-> DH+
– Allows PLC5s and SLCs to communicate
SLC 5/04
RSLogix 500
Software
PLC-5
PLC-5
DH+
DH+
DH-485 Network #2
DH-485 Network #1
Link Coupler
Link Coupler
Link Coupler
Link Coupler
SLC 5/01
SLC 5/02
SLC 5/03
SLC 5/03
22
SLC 500 Communications
RS-232 Communications
SLC-5/03 and 5/04 Support:

Full-Duplex (Point-to-Point)

Half- Duplex

ASCII

Modem Communication
SLC 500 Communications
RS-232: DF1 Full-Duplex
AKA: DF1 Point-to-Point
Simultaneous transmission
between two devices in both
directions

- Programming Port
- Peer Messaging
SLC 500 Communications
RS-232: DF1 Half-Duplex

Mulit-Drop, Single Master, Multiple Slave

Slaves are Polled for Response from the Master

Supports up to 255 Slave Devices

Slaves: Any SLC Processor

Master: PLC-5, SLC-5/03, 5/04, CV
SLC 500 Communications
5/03 + 5/04 Serial Port

Point-to-point communications

RS-232

Using Channel 0 w/ DF1 Full-Duplex
RSLogix 500
Programming Software
Modem
Modem
SLC 5/03 or 5/04
26
SLC 500 Communications
5/03 + 5/04 Serial Port

Master/Slave communications

Polled Network

Using Channel 0 w/ DF1 Halfduplex Master or Slave
Master
DF1 Master (RSView)
Modem
Slave(s)
Modem
RSLogix 500 Programming Software
Modem
Modem
SLC 5/03
SLC 5/04
27
SLC 500 Communications
ASCII Communications

5/03 and 5/04

Direct connection to devices such as
barcode decoders and printers

Eliminates requirement of BASIC module
for this task
SLC 5/03 CPU
RUN
FORCE
FLT
DH485
BATT
RS232
RUN REM PROG
28
SLC 500 Communications
1747-KE Module

DH-485 / RS-232
ACT
485
CFG
DF1
FAULT
BA LOW
H/D
F/D
Converts electrical signals
– RS-485 to RS-232

Translates protocols
– DH-485 to DF1

Configured thru the backplane
(Series B)
RS-232
Config
RS-232
DF1
RS-485
DH-485
29
SLC 500 Communications
1747-KE Module
DH-485 / RS-232

RS-485/DH-485 to RS-232C/DF1
interface module

Acts as a BRIDGE between two
different networks or types of
communication

Called a Bridge module

(1) DH-485 port

(2) Serial ports (RS-232, 422, 485)

Allows remote communications to
SLC 500 systems
ACT
485
CFG
DF1
FAULT
BA LOW
H/D
F/D
30
SLC 500 Communications
Typical KE Configurations
RSLogix 500
• Point-to-Point configuration
using full duplex DF1
communications
• Remote communications from
the programming software to a
remote network of SLC 500
processors.
Modem
Modem
SLC 500
SLC 500 CPU with KE module
• RSLogix 500 acts as if it were
directly on the DH-485
network
DH-485
Isolated Link
Coupler
1747-AIC
SLC 5/01
31
SLC 500 Communications
Typical KE Configurations

Master/Slave communications

Polled Network

Master
DF1 Master (RSView)
Using Channel 0 w/ DF1 Halfduplex Slave
Modem
Slave(s)
Modem
RSLogix 500 Programming
Software
Modem
SLC 500
with KE
Modem
Modem
SLC 5/02
with KE
SLC 5/01
with KE
32
SLC 500 Communications
Peer-to-Peer Communications
Read/Write: Read - local processor is receiving data
Write - local processor is sending data
Target Device: 500CPU if target is another SLC Processor
485CIF if target is a non-SLC device on the network
PLC5 if target device accepts PLC-5 commands
Local/Remote: Local - the message is to be communicated via a local network
Remote - the message is to be communicated to a remote
device on another network through a bridge
Control Block: Contains - target node address, local file address,
target file address, status bits
MSG
Control Block Length: Fixed at 14 elements
Setup Screen: Advanced setup parameters
EN: enable bit - set when rung is true
DN: done bit - message successfully transmitted
ER: error bit - transmission failed
Read/Write Message
Type
Peer-To-Peer
Read/Write
Read
Target Device
500CPU
Local/Remote
Local
Control Block
?
Control Block Length
14
Setup Screen
( EN )
( DN )
( ER )
33
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