Servo control
4.20 Central probe evaluation
Drive functions
Function Manual, 11/2017, 6SL3097-4AB00-0BP5
185
Central measurement without handshake, more than two edges
With p0684 = 16, you activate the evaluation procedure without handshake for the central
probe evaluation. You can evaluate up to 16 signal edges from a maximum of 2 probes
simultaneously within a DP cycle.
DP cycle = PROFIBUS cycle = T
DP
T
MAPC
= master application cycle time (time grid, in which the master application generates
new setpoints).
● For each probe, up to 8 rising and/or 8 falling edges can be detected in each DP cycle
and saved in a measurement buffer.
● For each probe it can be selected whether the rising or falling signal edges are to be
taken into account.
● The cyclic measurement is activated with a 0/1 transition of the control bit for the signal
edges in the probe control word.
● After activating the measurement, the measured value buffer is emptied once for
initialization.
● When the buffer is full, the oldest measured value is overwritten first (first in/first out). The
bit "measured value buffer full" in the probe-diagnostic word signals the risk of losing
measured values.
● The measured value buffer is then cyclically emptied and the measured values are
converted in the sense of a measuring task into a time stamp. The time stamps are saved
according to their chronological order, starting with the oldest, in the indexes of parameter
r0565[0...15] for the transfer.
● If several probes of being used, then the time stamps of the measurements are entered
into the telegram block, corresponding to their chronological sequence, from the lowest
up to the highest probe.
● Up to 16 time stamps (MT_ZS), can be entered into telegram 395.
● As soon as there is no longer any space for the time stamps of a probe in telegram 395,
then the "Telegram full" is set in MT_DIAG.
Example:
– 4 values are transferred from the 1st probe
– 6 values are transferred from the 2nd probe
– Only the first 6 measured values are transferred from the 3rd probe - the rest is cut off
and "Full telegram" is signaled in MT_DIAG.
● From a selected probe, all signal edges are always taken into account. Individual signal
edges cannot be selected or deselected.
● The time stamps are transferred in parallel (to acquire new probe events associated with
a time stamp without handshake). A time stamp is only transferred for one DP cycle.
Then the time stamp overwritten with zero or a new time stamp.
● The cyclic measurement is deactivated with a 1/0 transition of the control bit for a falling
or rising signal edge in the probe control word.
● Transfer with PROFIdrive telegram 395.
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