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Allen Bradley serial communication
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HISTORY AND THEORY OF SERIAL COMMUNICATIONS
Circa 1960
HISTORY
RS-232 was first introduced in 1962 by the Radio Sector of
the Electronic Industries Alliance (Bell Systems driven)
teleprinter (teletypewriter, Teletype or TTY) is an
electromechanical typewriter that can be used to
communicate typed messages from point to point and
point to multipoint over a variety of communication channels
that range from a simple electrical connection, such as a pair
of wires, to the use of radio and microwave as the
transmission medium
HISTORY
Allowed Journalist to get articles to the newspaper
faster.
Previously had to send stories snail mail
Now they could go to the local MA BELL office and
wait in line to transcribe their story into a dumb
terminal.
HISTORY
HISTORY
RS232 was adopted my the first computer manufactures
Predecessors to USB devices.
Two Types
Data Terminal Equipment
AKA….DTESLC/PLC5/Logix
Family (Channel 0)COMPUTER COM
ports
Data Communication Equipment
AKA….DCEModems, PrintersDF1 PanelViews =
2711-xxx16, -xxx17DH485 (RS232)
PanelViews = 2711-xxx5, -xxx9
Cable Requirements
To connect a DTE device to DTE device a null modem cable is needed.
To connect a DTE device to DCE device a straight thru cable is needed.
To connect a DCE device to DCE device a null modem cable is needed
Cable Requirements
To connect a AB PLC to PC you need a Null Modem Cable
To connect a PC to a Panel View you need a straight thru or null modem adapter
A null modem cable with a null modem adapter connected becomes a straight thru cable.
AB typical null modem cablefull duplex
Signal OriginDB-
9 pinName Typical purposeAbbreviation
DTE DCE
Data Terminal Ready
Indicates presence of DTE to DCE. DTR ● 4
Data Carrier Detect
DCE is connected to the telephone line. CD ● 1
Data Set Ready
DCE is ready to receive commands or data. DSR ● 6
Ring Indicator
DCE has detected an incoming ring signal on the telephone line. (Unused)
RI ● 9
Request To Send
DTE requests the DCE prepare to receive data. RTS ● 7
Clear To Send
Indicates DCE is ready to accept data. CTS ● 8
Transmitted Data
Carries data from DTE to DCE. TxD ● 3
Received Data
Carries data from DCE to DTE. RxD ● 2
Common Ground
GND common 5
AB typical null modem cablefull duplex
Right Click and select Acrobat Document then open
AB cable Pinout
Click file to open
1747-CP3_1756-CP3-PinOut.pdf
1761-CBL-AS03 & 1761-CBL-AS09 Cable Pin-Out.pdf 1761-CBL-PM02-PinOut.pdf
1784-CAK-PinOut.pdf
1784-CP3-PinOut.pdf
1784-CP10-PinOut.pdf
2711-NC21 and 2711-NC22 cables for the PanelView.pdf
Null modem cable using only 3 wires full duplex.
Signal OriginDB-
9 pinName Typical purposeAbbreviation
DTE DCE
Data Terminal Ready
Indicates presence of DTE to DCE. DTR ● x
Data Carrier Detect
DCE is connected to the telephone line. CD ● x
Data Set Ready
DCE is ready to receive commands or data. DSR ● x
Ring Indicator
DCE has detected an incoming ring signal on the telephone line. (Unused)
RI ● x
Request To Send
DTE requests the DCE prepare to receive data. RTS ● x
Clear To Send
Indicates DCE is ready to accept data. CTS ● x
Transmitted Data
Carries data from DTE to DCE. TxD ● 3
Received Data
Carries data from DCE to DTE. RxD ● 2
Common Ground
GND common 5
Full Duplex VS Half Duplex
Full DuplexSend and Receive
data at the same time
Phone
Half DuplexLimited to only
Send or Receive at the same time
Walkie-Talkie
Common AB Baud Rates in Bits Per Second
300, 600, 1200, 2400,48009600 (Default for most SLC series)19200 (Standard Max Rate setting for
SLC series)38.4 K Max rate in control logix and
newer micro logix
Typical RSLinx serial Config Screen
What does UPLOAD and DOWNLOAD mean?
This can change with the make of the PLCWe will talk about the most common
version and the one AB uses.Download means taking information from
the programming terminal to the PLC or Device.
Upload means taking information from PLC or Device into the programming terminal.
Support
Rockwell Knowledge Base https://rockwellautomation.custhelp.com/app/home
GoogleRockwell Tech 1-440-646-3100Email MeFree Starter Software http://
www.ab.com/linked/programmablecontrol/plc/micrologix/downloads.html
http://www.rockwellautomation.com/rockwellsoftware/design/rslogix5000/demo.html