Siemens Simatic ET 200SP Equipment Manual page 20

Product overview
2.2 Functions
Examples of determining measured values
Use STEP 7 device configuration to set the values for the module in the following examples.
For your velocity in meters per second, you set the "Time Base for Velocity Measurement"
field to the value "1 second" and the "Counts per Unit for Velocity" to how many counts per
meter the encoder will generate. The velocity value returned to your safety program will be
the meters per second value * 1000. Multiplying the meters per second value by 1000
ensures the velocity value has sufficient resolution to show the fractional portion of the
calculation.
Setting "Velocity" in meters per second
You set the parameter values as follows:
• "Measured value" to "Velocity"
• "Update Time" to 1000 milliseconds - Provides an updated velocity calculation to your
safety program every second (1000 milliseconds)
• "Time Base for Velocity Measurement" value to "1 second"
• "Counts per Unit for Velocity" to 100 if your encoder generates 100 counts per meter
In this example, if you measured 452 counts during the one second update time and there
are 100 counts per meter, the movement distance is 4.52 meters during the one second
update time. Since the desired unit is meters per second, the velocity returns as a scaled
value (velocity * 1000) and your safety program sees the velocity as 4520. You would then
interpret the value as 4.520 meters per second.
Setting the "Update Time" to "100 milliseconds"
Use the same setup as the previous example, but set the "Update Time" to 100 milliseconds.
In this example, if you measure about 45 counts during the update time, convert this to
meters per second. The result is a velocity measurement of 4500 which is 4.500 meters per
second.
The module measured 4.5 meters per second, which is fewer than the previous measurement
4.52 meters per second. This results in you losing some resolution in the velocity
measurement because of the shorter update time.
Setting the "Time Base for Velocity Measurement" to "100 milliseconds"
Use the same setup as the first example, but set the "Time Base for Velocity Measurement" to
meters per 100 milliseconds.
In this example, if you measure 452 counts during the one second update time and there are
100 counts per meter, the movement distance is 4.52 meters during the one second update
time. Since you want meters per 100 milliseconds, the velocity returns as a scaled value
(velocity * 1000) and your safety program sees the velocity as 452. You would then interpret
the value as 0.452 meters per 100 milliseconds.
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ET 200SP F-TM Count 1x1Vpp sin/cos HF (6ES7136-6CB00-0CA0)
Equipment Manual, V1.0, 01/2021, A5E47073911-AA