then what is difference between C and IFM IN CPUS
ChatGPT said:
Excellent — this is a very good and practical question 👏
Let’s clearly understand the difference between “C” and “IFM” in Siemens PLC CPUs
(mainly S7-300 / S7-400 series).
🔹 Both “C” and “IFM” mean that the CPU has built-in I/O
…but they are different generations and design concepts.
Feature
IFM (Integrated Function
Module)
C (Compact CPU)
Meaning
Older term meaning CPU
has some integrated I/O
(digital + analog).
Newer Compact version of CPU with
built-in I/O and extra features.
Typical
Models
CPU 313-IFM, CPU 414-IFM
CPU 312C, 313C, 314C-2DP, 3152PN/DP (Compact versions)
Generation / Early design (older series,
Design
simpler I/O)
Later design (modern compact CPUs)
I/O Capacity
Limited (e.g. 16 DI, 16 DO, 4 Usually more (e.g. 24 DI, 16 DO, 4 AI, 2
AI, 2 AO)
AO)
Additional
Features
Basic digital & analog I/O
only
High-speed counters (HSC), Pulse
outputs (PTO), integrated PROFIBUS or
PROFINET communication
Flexibility
Fewer configuration options
More advanced and flexible (better
diagnostics, faster processing)
Typical Use
Small/simple applications,
older systems
Compact modern systems, motion
control, communication-heavy
applications
� In short:
Term Quick Meaning
IFM Old generation CPU with basic built-in I/O
C
New generation Compact CPU with built-in I/O + advanced functions (HSC,
PTO, DP/PN ports)
💡 Example Comparison:
Model
Built-in I/O
Special Features
CPU 313-IFM
16 DI, 16 DO, 4 AI, 2 AO Basic I/O only
CPU 314C-2DP 24 DI, 16 DO, 4 AI, 2 AO HSC, PTO, 2 PROFIBUS ports
Would you like me to give you a comparison chart between 313-IFM, 313C, and
314C-2DP (to see evolution step-by-step)?