Rated output current
- as output for standard mode 0.5 A per channel
- as output for technology functions, you can select between an output current of up to
0.5 A for an output frequency up to 10 kHz (load dependent) and a reduced output
current of max. 0.1 A at an increased output frequency of up to 100 kHz
– Suitable for, e.g., solenoid valves, DC contactors and indicator lights or also for signal
transmission or for proportional valves
– Configurable diagnostics
– Support of the value status (Quality Information, QI)
You can find a table showing the output frequencies and output currents through which
outputs is available in the section Interconnection overview of outputs (Page 100).
The digital outputs feature driver blocks with push-pull outputs. Due to their basic
functional design, such driver blocks always contain parasitic diodes, that act as
freewheeling diodes when shutting off inductive loads (see figure "Current flow with
correct wiring using the digital on-board I/O X11 as an example" in the section Terminal
and block diagram of the digital on-board I/O (Page 81)). The shutdown voltage is limited
to -0.8 V. Therefore, the demagnetization of inductive loads takes longer and can be
approximately calculated using the following formula.
tau = L / R (tau= time constant, L = inductance value, R = ohmic resistance value)
After the expiration of a period of 5 * tau, the current has decreased in effect to 0 A due to
the inductive load.
The maximum value is derived from: tau = 1.15H / 48 Ohm = 24ms. After
5 * 24 ms = 120 ms, the current has decreased in effect to 0 A.
For comparison: With standard modules, inductive shutdown voltage, for example, is
limited to Vcc -53 V (supply voltage – 53 V), so that the current has decreased to about to
0 A after 15 ms.
The digital on-board I/O supports the following functions:
● Reconfiguration in RUN
You can reconfigure some of the technological functions in the RUN mode of the CPU
(for more information, refer to the section Parameter assignment and structure of the
parameter data records of the digital on-board I/O (Page 158)).You can use technology and standard functions at the same time, provided the hardware
allows this. For example, all the digital inputs not assigned to the counting, measuring or
position detection or PTO technology functions can be used as standard DI.
Inputs to which technology functions are assigned can be read. Outputs to which technology
functions are assigned cannot be written.LEDs for the current operating mode and diagnostics status of the CPU
② Status and error displays RUN/ERROR of the analog on-board I/O
③ Status and error displays RUN/ERROR of the digital on-board I/O
④ Control keys
⑤ Display
Figure 2-4 View of the CPU 1512C-1 PN with closed front panels (front)
Note
Temperature range for display
To increase its service life, the display switches off at a temperature below the permitted
operating temperature of the device. When the display cools down again, it automatically
switches itself on again. When the display is switched off, the LEDs continue to show the
status of the CPU.
You can find additional information on the temperatures at which the display switches itself
on and off in the Technical specifications (Page 128). You can lock the front panel to protect your CPU against unauthorized access.
You can attach a security seal or a padlock with a hoop diameter of 3 mm to the front panel.
n addition to the mechanical lock, you can also block access to a password-protected CPU
on the display (local lock) and assign a password for the display. For more information on
the display, the configurable protection levels and the local lock, refer to the , ET LEDs for the current operating mode and diagnostics status of the CPU
② Status and error displays RUN/ERROR of the analog on-board I/O
③ Status and error displays RUN/ERROR of the digital on-board I/O
④ Fastening screw
⑤ Connection for supply voltage
⑥ PROFINET interface (X1) with 2 ports (X1 P1 and X1 P2)
⑦ MAC address
⑧ LEDs for the 2 ports (X1 P1 and X1 P2) of the PROFINET interface X1
⑨ Mode selector
⑩ Slot for the SIMATIC memory card
⑪ Display connection
Figure 2-6 View of the CPU 1512C-1 PN without front panel on the CPU (fronShield contact surfaces
② Plug-in connection for power supply
③ Plug-in connection for backplane bus
④ Fastening screws
Figure 2-7 View of the CPU 1512C-1 PN - rearYou use the mode selector to set the operating mode of the CPU.
The following table shows the position of the selector and the corresponding meaning:The technology functions of the compact CPU have the following technical properties:
● 32 high-speed digital inputs (up to 100 kHz), isolated
– 6 high-speed counters (High Speed Counter/HSC), which can all be used as A/B/N
● Interfaces
– 24 V encoder signals of sourcing or push-pull encoders and sensors
– 24 V encoder supply output, short-circuit-proof
– Up to 2 additional digital inputs per high-speed counter for possible HSC DI functions
(Sync, Capture, Gate)
– 1 digital output per high-speed counter for fast reaction to the count

Counting range: 32 bits
● Diagnostics and hardware interrupts can be configured
● Supported encoder/signal types
– 24 V incremental encoder
(with 2 tracks A and B, phase-shifted by 90°, up to 6 incremental encoders also with
zero track N)
– 24 V pulse encoder with direction signal
– 24 V pulse encoder without direction signal
– 24 V pulse encoder each for forward pulse & reverse pulse
The high-speed counters support reconfiguration in RUN. You can find additional information
in section Parameter data records of the high-speed counters (Page 162).Counting refers to the detection and adding up of events. The counters acquire and evaluate
encoder signals and pulses. You can specify the count direction using encoder or pulse
signals or through the user program.
You can control counting processes using the digital inputs. You can switch the digital
outputs exactly at defined count values, regardless of the user program.
You can configure the response of the counters using the functionalities described below.
Counting limits
The counting limits define the count value range used. The counting limits are selectable and
can be modified during runtime by the user program.
The highest counting limit that can be set is 2147483647 (231–1). The lowest counting limit
that can be set is –2147483648 (–231).
You can configure the response of the counter at the counting limits:
● Continue or stop counting (automatic gate stop) on violation of a counting limit
● Set count value to start value or to opposite counting limit on violation of a counting limit
Start value
You can configure a start value within the counting limits. The start value can be modified
during runtime by the user program.
Depending on the parameter assignment, the compact CPU can set the current count value
to the start value during synchronization, during the Capture function, on violation of a
counting limit or when the gate is opened.
Gate control
Opening and closing the hardware gate and software gate defines the period of time during
which the counting signals are acquired.
The digital inputs of the digital on-board I/O control the hardware gate. The user program
controls the software gate. You can enable the hardware gate using the parameter
assignment. The software gate (bit in the control interface of the cyclic I/O data) cannot be
disabled.
Capture
You can configure an external reference signal edge that triggers the saving of the current
count value as a Capture value. The following external signals can trigger the Capture
function:
● Rising or falling edge of a digital input
● Both edges of a digital input
● Rising edge of signal N at the encoder input
You can configure whether counting continues from the current count value or from the start
value after the Capture functionYou can specify hysteresis for the comparison values, within which a digital output is
prevented from switching again. An encoder may stop at a certain position, and slight
movements may make the count value fluctuate around this position. If a comparison value
or a counting limit lies within this fluctuation range, the corresponding digital output will be
switched on and off often if hysteresis is not used. The hysteresis prevents these unwanted
switching operations.
Reference
For more information on the counter, refer to the , ET 200MP, ET 200SP Counting,
measurement and position detection function manuaThe following measuring functions are available:
Table 3- 1 Overview of available measuring functions
Measurement type Description
Frequency measurement A measuring interval calculates the average frequency based on the time sequence of the
count pulses, and returns this frequency as a floating-point number in units of hertz.
Period measurement A measuring interval calculates the average period duration based on the time sequence of