Continuous Rotational Speed Measurement - Siemens SIMATIC ET 200S Operating Instructions Manual

2.7.6

Continuous Rotational Speed Measurement

Definition
In rotational speed measurement mode, the 1Count24V counts the pulses that are received
from a tachometer generator within a dynamic measuring time, and calculates the speed
from this value with the number of pulses per encoder revolution.
Update time
The 1Count24V updates the measured values cyclically. You preset the update time with the
Update Time parameter (see table). You can change the update time during operation.
Table 2- 13 Calculation of the Update Time
Boundary conditions
Non-isochronous mode
Isochronous mode
Any digits after the decimal point resulting from division by T
1
These limits may not be violated. If these limits are violated, the 1Count24V generates a parameter assignment error and
will not go into isochronous mode.
Rotational Speed Measurement
For the rotational speed measurement mode, you must also assign the pulses per encoder
revolution.
The rotational speed is returned in the unit 1x10
Figure 2-26
Technological Functions
Operating Instructions, 06/2010, A5E00124867-07
Update time
Any T n x 10 ms
DP
T < 10 ms n x T
DP
T ≥ 10 ms n x T
DP
Rotational Speed Measurement with Gate Function
Range of n
n
min
1
(10 ms/T [ms]) + 1
DP DP
1
DP
are omitted.
DP
/min.
-3
1Count24V
2.7 Measurement Modes
n
max
1000
1000
1
10000 ms/T [ms]
DP
1
65