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Special Functions Module & Communications Processors


Point-to-Point link via communications processors (CPs) is an extremely powerful and low cost alternative to bus-systems. The advantage of point-to-point links over bus systems is especially pronounced when only a few (RS485) devices are to be connected to the SIMATIC S7.

The CPs can also economically connect third party systems to the SIMATIC S7. Thanks to the great flexibility of the CPs different physical transmission media, speeds or even customized transmission protocols can be implemented.

The configuring data are stored in a system data block stored in the CPU. When modules are replaced, the new module is therefore immediately ready for use.

Technical data
Point-to-Point Link
 Application Low-cost entry version Powerful computer conncetion, Loadable protocols
Transmision rate Low (19200 bit/s) High (76800 bit/s)
Loadable protocols   MODBUS master (6ES7340-1AA.),
MODBUS slave (6ES7340-1AB.),
Data highway (6ES7340-1AE.)
Module CP 340 CP 341
Order No. Group: 6ES7 340-1. 341-1.
Physical transmission media
RS 232C (V.24) CP 340-1A CP 341-1A
20 mA (TTY) CP 340-1B CP 341-1B
RS 422/485 (X.27) CP 340-1C CP 341-1C
Integrated transmission protocols
Printer driver
3964 (R)
RK 512  


Function m,odulesc are intelligent modules that independently
execute the technoogical tasks and thus reduce the load on the
CPU. They are used when a high level of accuracy and dyna,ic
response is required.

Function modules
Tchnological function Channels / Axes Modue
Counting, measuring, proportioning position detection (incremental) 1 FM350-1
Counting, measuring, proportining 8 FM 350-2 3)
Cam controls 1 FM 352
High-speed dinary logic operations 1 FM 352-
PID control (continuous) 4 FM 355C
PID control (step/impulse) 4 FM 355S
Temperature control (continuous) 4 FM 355-2C
Temperature control (step/impulse) 4 FM 355-2S
Positioning (rapid travers/creep feed) 2 FM 351
Position detection (SSI) 3 FSM 338
Positioning (with stepper drives) 1 FM 353
Positioning (with servo drives) 1 FM 354
Positioning, path control, interpolation, synchronization 4 FM 357-2
Isochronous connection of drives via PROFIBUS 4 IM 174


Commnuication processors are used for connecting S7-300
to the different dus systems / communication networks as well
for point-to-point link.

Communcations processors
Bus system /communication network Module
AS-Interface (mater) 2) CP 343-2
CP343-2 P
  CP342-5 FO
(for fiber-optic conductors)
PROFINET / Industrial Ethernet 2) CP 343-1 Lean
  CP 343-1
  CP 343-1 Advanced
(with IT functionnality)
Point-to-point link CP 340 4)
CP 341 4)
TIM 3V-IE Advanced



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