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 function.You 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 manual 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 the
count pulses, and returns this period duration as a floating-point number in units of seconds.
Velocity measurement A measuring interval calculates the average velocity based on the time sequence of the count
pulses, and returns this velocity in the configured unit.
The measured value and count value are both available in the feedback interface.
Update time
You can configure the interval at which the compact CPU updates the measured values
cyclically as the update time. Larger update times smooth uneven measured variables and
increase the measuring accuracy.
Gate control
Opening and closing the hardware gate and software gate defines the period of time during
which the count signals are acquired. The update time is asynchronous to the opening of the
gate, which means that the update time is not started when the gate is opened. After the
gate is closed, the last measured value calculated is still returnedFrequency measurement 0.04 Hz 400 kHz *
Period measurement 2.5 μs * 25 s
Velocity measurement Depending on the configured number of "increments per unit" and the "timebase
for velocity measurement"
* Applies to 24 V incremental encoder and "quadruple" signal evaluation
All measured values are returned as signed values. The sign indicates whether the count
value increased or decreased during the relevant time period. For example, a value of -
80 Hz means that the count value decreases at 80 Hz.
Reference
For more information on measuring, refer to the , ET 200MP, ET 200SP Counting,
measurement and position detection function manualYou can use the digital on-board I/O, e.g. with an incremental encoder, for position detection
with Motion Control. The position input is based on the counting function, which
evaluates the acquired encoder signals and provides them for Motion Control.
In the hardware configuration of the CPU 1512C-1 PN in STEP 7 (TIA Portal), select the
"Position input for Motion Control" mode.
Reference
For a detailed description of the use of motion control and its configuration, refer to the S7-
1500 Motion Control function manual the interface between the drives and encoders is referred to as a technology module (TM). In
this context, a technology module (TM) also refers to the digital on-board I/O of the compact
CPU described here.vYou can configure an external reference signal edge to load the counter with the specified
start value. The following external signals can trigger a synchronization:
● Rising or falling edge of a digital input
● Rising edge of signal N at the encoder input
● Rising edge of signal N at the encoder input depending on the level of the assigned digital
input
Comparison values
The integrated counter supports 2 comparison values and digital output HSC DQ1. If the
counter or measured value meets the set comparison condition, HSC DQ1 can be set in
order to trigger direct control operations in the process.
Both comparison values can be set in the parameters and can be changed during runtime by
the user program.
Hardware interrupts
If you have enabled a hardware interrupt in the hardware configuration, the counter can
trigger a hardware interrupt in the CPU when a comparison event occurs, if there is overflow
or underflow, at a zero crossing of the counter, and/or at a chan