Features	CPU 1511C-1 PN	CPU 1512C-1 PN
Work memory for program, integrated	175 KB	250 KB
Work memory for data, integrated	1 MB	1.5 MB
Load memory	Plug-in via SIMATIC memory card	Plug-in via SIMATIC memory card
Display diagonal	3.45 cm	3.45 cm
Command execution times
Bit operations	0.06 µs	0.048 µs
Word operations	0.072 µs	0.058 µs
Fixed-point operations	0.096 µs	0.077 µs
Floating-point operations	0.384 µs	0.307 µs
Bit memories, timers, counters
S7 counters/timers	2048 each	2048 each
IEC counter	arbitrary (only limited by the work memory)
IEC timer	arbitrary (only limited by the work memory)
Bit memories	16 KB	16 KB
I/O address range
Inputs	32 KB (all inputs are stored in the process image)
Outputs	32 KB (all outputs are stored in the process image)
Integrated inputs/outputs
Digital inputs (integrated)	16	32
Digital outputs (integrated)	16	32
Analog inputs (integrated)	5 (4 x U/I, 1 x RTD)	5 (4 x U/I, 1 x RTD)
Analog outputs (integrated)	2	2
Communication
PtP	Yes (via CM)	Yes (via CM)
PROFINET	Yes (via CM)	Yes (via CM)
PROFINET IO IRT	1 x PN IO IRT (2-port switch)	1 x PN IO IRT (2-port switch)
PROFIBUS	Yes (via CM)	Yes (via CM)
Web server	Yes	Yes
Integrated technological functions
High-speed counters (HSC)	6 (max. 100 kHz)	6 (max. 100 kHz)
Frequency meters	6 (max. 100 kHz)	6 (max. 100 kHz)
Period measurement	6 channels	6 channels