201 Publication 1747-UM011G-EN-P - June 2008
Appendix
C
RS-232 Communication Interface
This appendix provides an overview of the RS-232 communication
interface and explains how the SLC 5/03, SLC 5/04, and SLC 5/05
processors support it. This appendix also provides information on:
• RS-232 and SCADA applications.
• RS-232 communication interface overview.
• SLC 5/03, SLC 5/04, and SLC 5/05 processors and RS-232
communication.
• SLC 500 devices that support RS-232 communication.
• DF1 protocol and the SLC 5/03, SLC 5/04, and SLC 5/05 processors.
• Modbus RTU Master communication.
• ASCII communication.
• DF1 communication protocol modems overview.
• wiring connectors for RS-232 communication.
• applications for the RS-232 communication interface.
For online configuration procedures of the SLC 5/03, SLC 5/04, and
SLC 5/05 processors for DF1 protocol, see your programming software
user manual.
RS-232 and SCADA
Applications
RS-232 is a communication interface included under SCADA
(Supervisory Control and Data Acquisition) applications. SCADA is a
term that refers to control applications that require communication
over long distances. For more information about the use of
Allen-Bradley equipment in SCADA applications, refer to the SCADA
System Applications Guide, publication AG-UM008.
RS-232 Communication
Interface Overview
RS-232 is an Electronics Industries Association (EIA) standard that
specifies the electrical, mechanical, and functional characteristics for
serial binary communication.
One of the benefits of RS-232 communication is that it lets you
integrate telephone and radio modems into your control system. The
distance over which you are able to communicate with certain system
devices is virtually limitless.
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The RS-232 channel on the SLC 5/03, SLC 5/04, and SLC 5/05
processors supports various protocols:
• Full-duplex DF1 (default)
• Half-duplex DF1 (SCADA)
• DH-485
• ASCII communication
• DF1 radio modem
• Modbus RTU Master
The SLC and PLC products detailed in this appendix that communicate
over the RS-232 communication interface also use the DF1 serial
communication protocol. DF1 protocol delimits messages, controls
message flow, detects and signals errors, and retries after errors are
detected.
SLC 5/03, SLC 5/04, and SLC
5/05 processors and RS-232
Communication
The SLC 5/03, SLC 5/04, and SLC 5/05 processors can communicate by
means of the RS-232 communication port, channel 0. Channel 0 supports DF1
full-duplex protocol, DF1 half-duplex master and slave protocol, DH485
protocol, Modbus RTU Master communication, ASCII communication, and
DF1 radio modem protocol. Refer to your programming software user manual
for information on configuring the RS-232 communication port, channel 0.
The details of the DF1 protocols can be found in the DF1 Protocol and
Command Set Reference Manual, Publication Number 1770-6.5.16.
Channel 0 provides a minimum of 500V dc isolation between the I/O
signals and the logic ground of the SLC 5/03, SLC 5/04, and SLC 5/05
processors. The channel is a 9-pin D-shell. The table below provides a
description of each of the pins.
The D-shell is the bottom port on the SLC 5/03, SLC 5/04, and SLC 5/05
processors.
Pin Pin Name
1 DCD (Data Carrier Detect)
2 RXD (Receive Data)
3 TXD (Transmit Data)
4 DTR (Data Terminal Ready)
5 COM (Common Return [Signal Ground])
6 DSR (Data Set Ready)
7 RTS (Request to Send)
8 CTS (Clear to Send)
9 NC (No Connection)
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SLC 500 Devices that
Support RS-232
Communication
The SLC 500 product line has two other modules, aside from the SLC 5/03,
SLC 5/04, and SLC 5/05 processors, that support the RS-232 communication
interface. They are the 1746-BAS BASIC module and the 1747-KE
DH-485/RS-232C interface. Both of these modules can be used with either
the SLC 5/01 or SLC 5/02 processor.
1747-KE Module
The 1747-KE module is a communication interface module that acts as a
bridge between DH-485 networks and devices requiring DF1 protocol. You
can configure the DF1 port on the 1747-KE module for RS-232/423, RS-422,
or RS-485 devices. Residing in an SLC 500 chassis, the 1747-KE module is
ideally used as an interface module, linking remote DH-485 networks via a
modem to a central host.
For more information on the 1747-KE module, see the DH-485/RS-232
Interface Module User Manual, publication 1747-IN006.
1746-BAS and 1746-BAS-T Modules
The 1746-BAS and 1746-BAS-T modules, which are programmed using the
BASIC language, have two configurable serial ports for interfacing to
computers, modems, serial printers, and other RS-232 compatible devices.
You can also use them for off-loading complex math routines from an SLC
500 processor, thereby conserving ladder logic memory.
For more information on the 1746-BAS module, see the SLC 500 BASIC and
BASIC-T Module User Manual, publication 1746-UM004.
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DF1 Protocol and the SLC
5/03, SLC 5/04, and SLC 5/05
Processors
DF1 protocol combines data transparency (ANSI - American National
Standards Institute - specification subcategory D1) and 2-way
simultaneous transmission with embedded responses (F1). It is also a
peer-to-peer, link-layer protocol. This means that system devices have
equal access to messages being sent over the RS-232 communication
interface.
DF1 protocol provides two modes of communication: full-duplex and
half-duplex.
DF1 Full-duplex Protocol
DF1 full-duplex protocol (also referred to as DF1 point-to-point
protocol) lets you use RS-232 point-to-point communication in
applications that require it. This type of protocol supports
simultaneous transmissions between two devices in both directions.
You can use channel 0 as a programming port, or as a peer-to-peer
port using the MSG instruction.
In full-duplex mode, the SLC 5/03, SLC 5/04, and SLC 5/05 processors
can send and receive messages. When the SLC 5/03, SLC 5/04, and
SLC 5/05 processors receive messages, they act as an end device, or
final destination for the data packets
(1)
. The processor ignores the destination
and source addresses received in the data packets. However, the processor
swaps these addresses in the reply that it transmits in response to any
command data packet that it has received.
By setting a parameter with your programming software, you can also
make the processor verify that the host computer can receive
embedded responses. To do this, the processor waits to receive an
embedded response from the host computer, before sending one of its
own. A host computer that can send embedded responses should also
be able to receive them.
If you use modems with DF1 full-duplex protocol, make sure that they
are capable of simultaneous bidirectional communication. Typically,
dial-up modems designed to be connected to standard telephone lines
can support full-duplex.
(1)
The exceptions to this are SLC 5/04 and SLC 5/05 processors that have the DH+ to DF1 or Ethernet to DF1
full-duplex passthru bit enabled. In the case of the SLC 5/04, the processor checks the destination address in
the packet and if it does not match the configured DH+ address of the processor, the packet is forwarded onto
the DH+ network to the destination address DH+ node. In the case of the SLC 5/05, the processor checks the
destination address in the packet. If the routing table exists and an IP address is in the routing table for that
DF1 address, the packet is forwarded out to the Ethernet network to that IP address.
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Full-duplex (Point-to-Point)
DF1 Half-duplex Protocol
DF1 half-duplex protocol provides a multi-drop single master/multiple
slave network. In contrast to the DF1 full-duplex protocol,
communication takes place in one direction at a time. You can use
channel 0 as a programming port, or as a peer-to-peer port using the
MSG instruction.
In half-duplex mode, the SLC 5/03, SLC 5/04, and SLC 5/05 processors
can be either master or slave devices. As a master device, the
processor polls each slave on the network on a regular and sequential
basis. The master also supports routing of data packets from one slave
to another, or slave-to-slave communication. As a slave device, the
processor can send data packets when polled by the master device,
which initiates all communication with slave devices.
If the master device has no data to send, it can still receive data from
the slave device. To do this, the master sends out a poll packet
addressed to the slave. If the slave has data to send, it does so in
response to the poll packet. Otherwise, the slave sends a simple
two-byte response, so that the master knows that it is active.
Several Allen-Bradley products support half-duplex master protocol.
They include the Enhanced PLC-5 processors, and SLC 5/03, SLC 5/04,
and SLC 5/05 processors. RSLinx (2.0 or later) software also supports
half-duplex master protocol.
DF1 Half-duplex supports up to 255 slave devices (addresses 0...254)
with address 255 reserved for master broadcasts. The SLC 5/03,
SLC 5/04, and SLC 5/05 processor support broadcast reception. SLC
5/03, SLC 5/04, and SLC 5/05 processors with operating system FRN
C/6 can also initiate broadcast write commands via the MSG
Modem
SLC 5/03
Processor
(1747-L532)
1747-CP3 Cable
Modem
SLC 5/03
Processor
(1747-L532)
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instruction for all channel 0 system mode drivers and for channel 1
(DH-485) on the SLC 5/03 processor.
Either half-duplex or full-duplex modem types can be used for the
master, but half-duplex modems must be used for the slaves
(assuming there is more than one on a multi-drop network).
TIP
Broadcast is not supported for read commands or any remote
messages. Broadcast is also not supported by the SLC 5/04
channel 1 DH+ network or the SLC 5/05 channel 1 Ethernet
network.
Modular Controller with SLC
5/02 Processor and 1747-KE
Interface Module (slave)
Modular Controller with
SLC 5/03 Processor (slave)
Modular Controller with SLC
5/01 Processor and 1747-KE
Interface Module (slave)
Fixed Controller with 1747-KE
Interface Module (slave)
Personal Computer
Running RSLinx with DF1
Half-duplex Protocol
(master)
RS-232 (DF1 protocol)
Modem Modem Modem Modem
Modem
Modular Controller with SLC
5/02 Processor and 1747-KE
Interface Module (slave)
Modular Controller with
SLC 5/03 Processor (slave)
Modular Controller with SLC
5/01 Processor and 1747-KE
Interface Module (slave)
Fixed Controller with 1747-KE
Interface Module (slave)
Modular Controller with
SLC 5/03 Processor
(master)
RS-232 (DF1 protocol)
Modem Modem Modem Modem
Modem
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DF1 Radio Modem Channel 0 Driver
Series C FRN 6 (FRN C/6) and later versions of operating systems
OS302 (SLC 5/03 processor), OS401 (SLC 5/04 processor) and OS501
(SLC 5/05 processor) include a channel 0 system mode driver called
DF1 radio modem. This driver implements a protocol, optimized for
use with radio modem networks, that is a hybrid between DF1
full-duplex protocol and DF1 half-duplex protocol, and therefore is
not compatible with either of these protocols.
Like DF1 full-duplex protocol, DF1 radio modem allows any node to
initiate to any other node at any time (if the radio modem network
supports full-duplex data port buffering and radio transmission
collision avoidance). Like DF1 half-duplex protocol, a node ignores
any packets received that have a destination address other than its
own, with the exception of broadcast packets and passthru packets.
Unlike either DF1 full-duplex or DF1 half-duplex protocols, DF1 radio
modem protocol does not include ACKs, NAKs, ENQs, or poll
packets. Data integrity is ensured by the CRC checksum.
Using the DF1 Radio Modem
The DF1 radio modem driver can be configured as the system mode
driver for channel 0 using RSLogix 500 version 5.50 or later software.
IMPORTANT
The DF1 radio modem driver should only be used among
devices that support and are configured for the DF1 radio
modem protocol. Only SLC 5/03, SLC 5/04 and SLC 5/05
processors with operating systems FRN C/6 support DF1 radio
modem protocol.
IMPORTANT
There are some radio modem network configurations that will
not work with the DF1 radio modem driver. (See DF1 Radio
Modem System Limitations on page 209.) In these
configurations, continue to use DF1 half-duplex protocol.
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Channel O Configuration
The Baud, Parity, Stop Bits and Error Detection selections are identical
to the other DF1 drivers. Valid Node Addresses are 0...254, just like the
DF1 half-duplex drivers.
The primary advantage of using DF1 radio modem protocol for radio
modem networks is in transmission efficiency. Each read/write
transaction (command and reply) requires only one transmission by
the initiator (to send the command) and one transmission by the
responder (to return the reply). This minimizes the number of times
the radios need to key-up to transmit, which maximizes radio life and
minimizes radio power consumption. In contrast, DF1 half-duplex
protocol requires five transmissions for the DF1 master to complete a
read/write transaction with a DF1 slave - three by the master and two
by the slave.
The DF1 radio modem driver can be used in a pseudo master/slave
mode with any radio modems, as long as the designated master node
is the only node initiating MSG instructions, and as long as only one
MSG instruction is triggered at a time.
For modern serial radio modems that support full-duplex data port
buffering and radio transmission collision avoidance, the DF1 radio
modem driver can be used to set up a masterless peer-to-peer radio
network, where any node can initiate communication to any other
node at any time, as long as all of the nodes are within radio range so
that they receive each other’s transmissions.
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DF1 Radio Modem System Limitations
The following questions need to be answered in order to determine if
you can implement the new DF1 radio modem driver in your radio
modem network.
• Are all of the devices SLC 5/03, 5/04 or 5/05 processors?
If so, then they must all be at operating system FRN C/6 or later
in order to be configured with the DF1 radio modem driver
using RSLogix 500 version 5.50 or later software. If not, then
make sure that all of the nodes can support the DF1 radio
modem protocol. Once channel 0 is configured for DF1 radio
modem, you will need to use channel 1 to locally monitor and
program your SLC processor using RSLogix 500 software.
• Does each node receive the radio transmissions of every other
node, being both within radio transmission/reception range and
on a common receiving frequency (either via a Simplex radio
mode or via a single, common, full-duplex repeater)?
If so, then go to the next question to see if you can use the DF1
radio modem driver to set up a peer-to-peer radio network. If
not, then you may still be able to use the DF1 radio modem
driver, but only if you limit MSG instruction initiation to the
node connected to the master radio modem whose
transmissions can be received by every other radio modem in
the network.
• Do the radio modems handle full-duplex data port buffering and
radio transmission collision avoidance?
If so, and the answer to the previous question is yes as well,
then you can take full advantage of the peer-to-peer message
initiation capability in every node (for example, the ladder logic
in any node can trigger a MSG instruction to any other node at
any time). If not, then you may still be able to use the DF1 radio
modem driver, but only if you limit MSG instruction initiation to
a single master node whose transmission can be received by
every other node.
• Can I take advantage of the SLC 5/03, SLC 5/04, and 5/05
channel-to-channel passthru to remotely program the other SLC
nodes using RSLinx and RSLogix 500 running on a personal
computer connected to a local SLC processor via DH-485, DH+,
or Ethernet?
Yes, with certain limitations imposed based on the radio modem
network.
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Modbus RTU Master
Communication
Modbus RTU communication lets you connect the SLC 5/03, SLC 5/04, and
SLC 5/05 processors to Modbus RTU slave devices for exchange of data
values.
For an overview of the Modbus RTU Master protocol modem, refer to the
SLC 500 Instruction Set Reference Manual (1747-RM001).
ASCII Communication
ASCII pr otocol lets you connect the SLC 5/03, SLC 5/04, and SLC 5/05
processors to serial printers, personal computers, and other third-party
devices. ASCII protocol lets your ladder program manage ASCII data.
DF1/Modbus RTU
Communication Protocol
Modems Overview
You can connect the SLC 5/03, SLC 5/04, and SLC 5/05 processors to
several types of modems. In all cases, the processors act as Data Terminal
Equipment (DTE). DTE send and/or receive data on a network. Modem or
line drivers act as Data Communication Equipment (DCE), which provide the
signal conversion and coding required for communication between DTE and
data circuits. Other DCE include phone-line modems and specialized
modems, such as radio and satellite-link modems.
In addition to Common Return (COM), Receive Data (RXD), and Transmit
Data (TXD), the following active modem-control lines are provided on the
SLC 5/03, SLC 5/04, and SLC 5/05 processors.
RTS (Request to Send) - this output signal indicates to the modem or other
DCE that the DTE wants to transmit.
CTS (Clear to Send) - this input signal from the modem indicates the modem
is ready to receive the transmission by the DTE for forwarding over a link.
DSR (Data Set Ready) - this input signal indicates the DCE device is ready for
operation. Loss of this signal causes a modem-lost condition in the processor.
DTR (Data Terminal Ready) - this output signal from the DTE indicates that
it is ready for operation. You can also use this signal with the processor to
initiate DTR dialing in dial-up modems that support such a feature.
Modular Controller with
SLC 5/03 Processor
RS-232 Channel 0
1747-CP3 Cable
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DCD (Data Carrier Detect) - this is an input signal from the DCE that
indicates a carrier signal is being received and that presumably data is to be
received for forwarding to the DTE connected.
Wiring Connectors for
RS-232 Communication
To connect Allen-Bradley devices with other devices over RS-232, you must
wire the cable connectors so that communication can occur through the
cabling, which provide the interface between devices.
Types of RS-232 Connectors
The figures below show male connectors, and their pinout locations, for
Allen-Bradley devices.
DTE Pinout
Channel 0 is configured as DTE for all SLC 5/03, SLC 5/04, and SLC 5/05
processors. The pinouts are the same as the 9-pin personal computer port.
DTE 9 Pinout Signal is Equivalent
DTE 15 Pinout
Equivalent
DTE 25 Pinout
Pin Description
1 DCD Data Carrier Detect Input 8 8
2 RXD Received Data Input 3 3
3 TXD Transmitted Data Output 2 2
4 DTR Data Terminal Ready Output 11 20
5 COM Common Return (Signal
Ground)
Shared 7 7
6 DSR Data Set Ready Input 6 6
25
24
23
22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
8
7
6
5
4
3
2
1
15
14
13
12
11
10
9
5
4
3
2
1
9
8
7
6
9-Pin Connector (male) 15-Pin Connector (male) 25-Pin Connector (male)
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DCE Pinout
Devices such as a modem are DCE. The pinouts on these terminals
are wired to interface with DTE.
7 RTS Request to Send Output 4 4
8 CTS Clear to Send Input 5 5
9 NC No Connection Input 22 (RI Ring
Indicator)
DCE 9 Pinout Signal is Equivalent DCE 25
Pinout
Pin Description
1 DCD Data Carrier Detect Input 8
2 RXD Received Data Input 3
3 TXD Transmitted Data Output 2
4 DTR Data Terminal Ready Output 20
5 COM Common Return (Signal Ground) Shared 7
6 DSR Data Set Ready Input 6
7 RTS Request to Send Output 4
8 CTS Clear to Send Input 5
9 RI Ring Indicator Input 22
IMPORTANT
DCE signal names are viewed from a DTE perspective. For
example, TXD is a DTE output and also a DCE input.
DTE 9 Pinout Signal is Equivalent
DTE 15 Pinout
Equivalent
DTE 25 Pinout
Pin Description
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Pin Assignments for Wiring Connectors
Use the following pin assignments to wire the connectors of
Allen-Bradley control devices with modems and peripheral devices
that support RS-232 communication. See the table below to find the
wiring diagram that you need.
Personal Computer to a Modem (Hardware Handshaking Enabled)
(1) Connect to the shield of the cable.
To connect this
device
To this Device Remarks See this
page
Personal computer Modem Hardware handshaking enabled 213
Peripheral DTE Hardware handshaking disabled 214
SLC 5/03, SLC 5/04,
and SLC 5/05
processors
Modem Hardware handshaking enabled 214
Peripheral DTE Hardware handshaking disabled 215
Personal Computer Using a 1747-CP3 cable 215
1747-KE module Modem Hardware handshaking enabled 216
Peripheral DTE Hardware handshaking disabled 216
1746-BAS module Modem Hardware handshaking enabled 217
Peripheral DTE Hardware handshaking disabled 217
2760-RB module Modem Hardware handshaking enabled 218
Peripheral DTE Hardware handshaking disabled 218
PLC-5 (channel 0) Modem Hardware handshaking enabled 219
Peripheral DTE Hardware handshaking disabled 219
1
2
3
4
5
6
7
8
9
8
3
2
20
7
6
4
5
22
1
1
3
3
4
5
6
7
8
9
8
2
DCD
TXD
DTR
COM
DSR
RTS
CTS
RI
RXD
DCD
GND
(1)
TXD
DTR
COM
DSR
RTS
CTS
RI
RXD
2
20
7
6
4
5
22
25-Pin 9-Pin PC
Modem 9-Pin 25-Pin
DTE DCE
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Personal Computer to SLC 5/03, SLC 5/04, or SLC 5/05 Processor, 1770-KF3
Module, or PLC-5 Processor (Hardware Handshaking Disabled)
(1)
(1) You can also use the 1747-CP3 cable.
(2) Jumpers are only needed if you cannot disable the hardware handshaking on the port.
(3) Connect to the shield of the cable.
SLC 5/03, SLC 5/04, or SLC 5/05 Processor Connected to a Modem
(Hardware Handshaking Enabled)
(1) Connect to the shield of the cable.
1
3
2
4
5
6
7
8
8
2
3
20
7
6
4
5
1
1
3
3
4
5
6
7
8
9
8
2
DCD
TXD
DTR
COM
DSR
RTS
CTS
RI
RXD
DCD
TXD
DTR
COM
DSR
RTS
CTS
GND
RXD
2
20
7
6
4
5
22
(2)
(2)
(2)
(3)
(2)
25-Pin 9-Pin
PC
Modem 9-Pin 25-Pin
DTE
DCE
9-Pin
SLC
5/03
1
DCD
2
RXD
3
TXD
4
DTR
5
COM
6
DSR
7
RTS
8
CTS
9
NC
DTE DCE
Modem 9-Pin 25-Pin
(1)
GND
DCD
RXD
TXD
DTR
COM
DSR
RTS
CTS
RI
1
2
3
4
5
6
7
8
9 22
1
8
3
2
20
7
6
4
5
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SLC 5/03, SLC 5/04, or SLC 5/05 Processor to another SLC 5/03, SLC 5/04, or
SLC 5/05 Processor, Personal Computer, 1770-KF3 Module, or PLC-5
Processor (Hardware Handshaking Disabled)
(1)
(1) You can also use the 1747-CP3 cable.
(2) Jumpers are only needed if you cannot disable the hardware handshaking on the port.
(3) Connect to the shield of the cable.
SLC 5/03, SLC 5/04, or SLC 5/05 Processor Connected to a Personal
Computer with a 1747-CP3 Cable
(2)
9-Pin
(2)
SLC
5/03
1
DCD
2
TXD
3
RXD
4
DTR
5
COM
6
DSR
7
RTS
8
CTS
9
NC
DTE
Peripheral
Device
(3)
GND
DCD
TXD
RXD
DTR
COM
DSR
RTS
CTS
9-Pin 25-Pin
1
1
3
2
4
5
6
7
8
8
2
3
20
7
6
4
5
DCE
(2)
(2)
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1747-KE Module to a Modem (Hardware Handshaking Enabled)
(1) Connect to the shield of the cable.
1747-KE Module to a SLC 5/03, SLC 5/04, or SLC 5/05 Processor, Personal
Computer, 1770-KF3 Module, or PLC-5 Processor (Hardware Handshaking
Disabled)
(1)
(1) You can also use the 1747-CP3 cable.
(2) Jumpers are only needed if you cannot disable the hardware handshaking on the port.
(3) Connect to the shield of the cable.
Peripheral
GND
DSR
RXD
TXD
DTR
COM
DCR
RTS
CTS
RI
(1)
9-Pin 25-Pin
6
2
3
4
5
1
7
8
9 22
9-Pin 1747-KE
1
NC
2
RXD
3
TXD
4
DTR
5
COM
6
DSR
7
RTS
8
CTS
9
NC
Device
DTE DCE
1
6
3
2
20
7
8
4
5
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1746-BAS Module to a Modem (Hardware Handshaking Enabled)
(1) Connect to the shield of the cable.
1746-BAS Module to a SLC 5/03, SLC 5/04, or SLC 5/05 Processor, Personal
Computer, 1770-KF3 Module, or PLC-5 Processor (Hardware Handshaking
Disabled)
(1)
(1) You can also use the 1747-CP3 cable.
(2) Jumpers are only needed if you cannot disable the hardware handshaking on the port.
(3) Connect to the shield of the cable.
1746-BAS
9-Pin
1
NC
2
RXD
3
TXD
4
DTR
5
COM
6
DSR
7
RTS
8
CTS
9
NC
DTE DCE
Peripheral
Device
(1)
GND
DSR
RXD
TXD
DTR
COM
DCD
RTS
CTS
RI
25-Pin
9-Pin
6
2
3
4
5
1
7
8
9 22
1
6
3
2
20
7
8
4
5
Publication 1747-UM011G-EN-P - June 2008
218
RS-232 Communication Interface
2760-RB Module to a Modem (Hardware Handshaking Enabled)
(1) Connect the shield of the cable to the GND pin on one end only. Leave the other end open.
2760-RB Module to a SLC 5/03, SLC 5/04, or SLC 5/05 Processor, Personal
Computer, 1770-KF3 Module, or PLC-5 Processor (Hardware Handshaking
Disabled)
(1) You can also use the 1747-CP3 cable.
(2) Jumpers are only needed if you cannot disable the hardware handshaking on the port.
(3) Connect the shield of the cable to the GND pin on one end only. Leave the other end open.
Modem
25-Pin 2760-RB
GND
TXD
RXD
RTS
CTS
DSR
COM
DTR
(1)
1
2
3
4
5
6
7
20
DTE
GND
DCD
TXD
RXD
RTS
CTS
DSR
COM
DTR
RI
9-Pin 25-Pin
(1)
1
3
2
7
8
6
5
4
9
1
8
2
3
4
5
6
7
20
22
DCE
Publication 1747-UM011G-EN-P - June 2008
RS-232 Communication Interface
219
PLC-5 Processor (Channel 0) to a Modem (Hardware Handshaking Enabled)
(1) Connect to the shield of the cable.
PLC-5 Processor (Channel 0) to a SLC 5/03, SLC 5/04, or SLC 5/05 Processor,
Personal Computer, 1770-KF3 Module, PLC-5 Processor, 1747-KE Module, or
1746-BAS Module (Hardware Handshaking Disabled)
(1)
(1) You can also use the 1747-CP3 cable.
(2) Jumpers are only needed if you cannot disable the hardware handshaking on the port.
(3) Connect to the shield of the cable.
25-Pin PLC-5, CH0
8
DCD
3
RXD
2
TXD
20
DTR
7
COM
6
DSR
4
RTS
5
CTS
NC
22
Modem
GND
DCD
RXD
TXD
DTR
COM
DSR
RTS
CTS
RI
9-Pin 25-Pin
(1)
1
2
3
4
5
6
7
8
9
1
8
3
2
20
7
6
4
5
22
DTE DCE
Publication 1747-UM011G-EN-P - June 2008
220
RS-232 Communication Interface
Applications for the RS-232
Communication Interface
The figures below illustrate different applications for the RS-232
communication interface.
DF1 Full-duplex Peer-to-peer
Half-duplex with Slave-to-slave Routing
IMPORTANT
The 1747-KE module does not support slave-to-slave transfers.
Modem
SLC 5/03 Modular Controller SLC 5/03 Modular Controller
Modem
WINtelligent Linx or RSLinx
Running DF1 Half-duplex
Protocol (Master)
Modem
ModemModem Modem
SLC 5/03 Modular Controller SLC 5/03 Modular Controller
221 Publication 1747-UM011G-EN-P - June 2008
Appendix
D
Setting Up the DH+ Network
This appendix provides an overview of the Data Highway Plus (DH+)
communication protocol and explains how the SLC 5/04 processors support
it. This appendix also provides:
• a DH+ communication protocol overview.
• an SLC 5/04 processor and DH+ communication.
• wiring connectors for DH+ communication for SLC 5/04.
• a typical DH+ network configuration.
Data Highway Plus
Communication Protocol
Overview
Data Highway Plus implements peer-to-peer communication with a
token-passing scheme to rotate link mastership among a maximum of 64
nodes. Since this method does not require polling, it helps provide
time-efficient reliable data transport. The DH+ features:
• remote programming of PLC-2, PLC-3, PLC-5 and SLC 500 processors
on your network.
• direct connections to PLC-5 processors and industrial programming
terminals.
• easy re-configuration and expansion if you want to add more nodes
later.
• a communication rate of 57.6 Kbaud, 115.2 Kbaud, or
230.4 Kbaud.
The following table summarizes the type of termination resistor needed to
communicate at the specified communication rate with the maximum cable
length.
Termination Resistor and Communication Link
Termination Link Resistor
Value
Ω
Communication Rate
(Kbaud)
Maximum Cable Length
m (ft)
150 57.6 3048 (10,000)
150 115 1542 (5000)
82 230.4 762 (2500)
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222
Setting Up the DH+ Network
SLC 5/04 Processors and
DH+ Communication
The SLC 5/04 processors let you operate DH+ communication protocol by
means of the DH+ communication channel 1. The SLC 5/04 processors also
support DF1 full-duplex protocol, DF1 half-duplex master and slave protocol,
ASCII, or DH-485 via its RS-232 port, channel 0. The 3-pin connector,
provided with the SLC 5/04 processors, is for actual DH+ communication and
the 8-pin connector is for monitoring DH+ communication.
DH+ Channel 1, 3-Pin
DH+ Channel 1, 8-Pin
Pin Pin Name
1 DH+ Data Line 1
2 Shield
3 DH+ Data Line 2
Pin Pin Name
1 DH+ Data Line 2
2 No Connection
3 Shield
4 No Connection
5 No Connection
6 DH+ Data Line 1
7 No Connection
8 No Connection
Publication 1747-UM011G-EN-P - June 2008
Setting Up the DH+ Ne
twork 223
Channel 1 Location
SLC 5/04 CPU
RUN PROG
FORCE
RS232BATT
DH+FLT
RUN
REM
DH+
Channel 1
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224
Setting Up the DH+ Network
Wiring Connectors for DH+
Communication for SLC 5/04
Processors
To connect Allen-Bradley devices with other devices over DH+, you must wire
the 3-pin cable connectors so that communication can occur through the
cabling. Each device requires its own node address.
Terminate the DH+ link on both ends by connecting a 150 Ω, 1/2 W resistor
between terminals 1 and 2 of the 3-pin connector when you are
communicating at 57.6 Kbaud with a PLC-5 processor or 115.2 Kbaud with
other SLC 5/04 processors. Use an 82 Ω, 1/2 W resistor if you are
communicating at 230.4 Kbaud with other SLC 5/04 processors or series E
enhanced PLC-5 processor.
SLC 5/04 CPU
PROC
PROG
FORCE
COMM
BATT
RUN
R
E
M
PLC±5/20
PROGRAMMABLE
CONTROLLER
1
2
1
2
A B
SLC 5/04 CPU
1
2
RUN PROG
FORCE
RS232
BATT
DH+
FLT
RUN
REM
RUN PROG
FORCE
RS232
BATT
DH+
FLT
RUN
REM
Clear
Shield
Blue
Clear
Shield
Blue
Clear
Shield
Blue
Terminating
Resistor
Terminating
Resistor
ConnectorConnector Connector
Connector
Belden #9463 Cable
Belden #9463 Cable
Publication 1747-UM011G-EN-P - June 2008
Setting Up the DH+ Ne
twork 225
Minimizing Noise
To minimize the affect of noise on the SLC 5/04 processor, ground the cable
shields to earth via 0.01µF capacitors as shown in the DH+ wiring example
below. Only directly ground the shield at one point on the network.
S
LC 5/04 CPU
PROC
PROG
FORCE
COMM
B
ATT
RUN
R
E
M
PLC±5/20
PROGRAMMABLE
CONTROLLER
1
2
1
2
A B
S
LC 5/04 CPU
1
2
RU
N PROG
FORCE
RS232
BATT
DH+
FLT
RUN
REM
RUN PROG
FORCE
RS232
BATT
DH+
F
LT
RUN
REM
Clear
Shield
Blue
Clear
Shield
Blue
Clear
Shield
Blue
Terminating
Resistor
Terminating
Resistor
Connector Connector Connector
Belden #9463 Cable
Belden #9463 Cable
0.01µF
Shield
(1)
Shield
0.01µF
Shield
Earth Ground
Earth Ground
Earth Ground
(1) To chassis ground directly at one point only in the network.
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226
Setting Up the DH+ Network
Typical DH+ Network
Configuration
The following figure illustrates a possible configuration for the SLC 5/04
processor on a DH+ network. You can also use an SLC 500, SLC 5/01, SLC
5/02, SLC 5/03, or SLC 5/05 processor in place of the SLC 5/04 processor
on the DH+ network if the 1785-KA5 card is used with a PLC-5 processor.
The DH+ protocol uses factory set timeouts to restart token-passing
communication if the token is lost because of a defective node.
Other devices that use the DH+ network include those in the table below.
APS
DH+ Network
Personal Computer with 1784-KTXD or
1784-PKTX(D) Interface
PLC-5/15 Processor
PLC-5/15 Processor with a 1785-KA5
Card
SLC 5/04 Modular
Controller
1747-NET-AIC
Interface
Converter
SLC 5/02 Modular Controller SLC 5/03 Modular Controller
The PLC-5
Processor and
1785-KA5 Card
are daisy
chained
together.
1747-AIC
Converter
1747-AIC
Converter
1747-AIC
Converter
1747-AIC
Converter
Catalog Number Description Installation Requirement Function Publication
Number
1784-PCMK PCMCIA interface card PCMCIA slot in computer Provides DH+ or DH-485 connection 1784-UM519
1784-PKTX(D) Personal computer
DH+ interface card
PCI bus Provides DH+ or DH-485 connection 1784-UM527
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