User manual

106 Publication LOGIX-AP010B-EN-P - May 2010
Chapter 6 Communication and Networking
Logix Serial
Communication
The S5 serial communication modules were designed to communicate with
peripheral devices mainly by using RS-232 or the current-based TTY
protocols. Advances in communication technology and protocols has made
communication from a PLC to a peripheral device with RS-232 uncommon,
and TTY nearly obsolete. Compared to modern communication methods,
RS-232 and TTY are slow, susceptible to electrical noise, and restrictive in the
distance over which they operate. Furthermore, many modern peripheral
devices do not provide interfaces to connect by using RS232 or TTY. Even the
Siemens SIMATIC HMI Windows-based panel does not provide a TTY
interface to communicate with a SIMATIC S5 PLC (with the exception of the
MP 370 HMI panel that has a port that can be configured to be RS-232 or
TTY in the BIOS).
In converting from a S5 system to a Logix system, the built-in RS-232 port on
the Logix controller can replace the S5 communication modules in
communicating to a peripheral device.
The following Logix controllers have a built-in serial RS-232 port that
eliminates the need for the additional serial communication module as required
by the Siemens S5.
• 1756 ControlLogix and 1756 GuardLogix
• 1768 CompactLogix
• 1769 CompactLogix
• PowerFlex 700S Phase 2 with DriveLogix
The most modern peripheral devices communicate via Ethernet and any of the
following Logix Ethernet modules can communicate over an Ethernet
network.
• 1756-EN2T
• 1756-ENBT
• 1756-EN2F
The Logix EtherNet/IP module, 1756-EWEB provides remote access via an
Internet Browser to tags in a Logix controller.
If it is required to retain a peripheral device with TTY current loop interfaces,
a RS-232 to TTY conversion device should be used in conjunction with the
RS-232 serial port on the Logix controller.
TIP
The 1756-EN2F provides fiber-optic communication.