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Functions, monitoring and protective functions
9.3 Drive functions
9.3.25.12
"Tolerance band pulse number" monitoring
This function monitors the number of encoder pulses between two zero marks. An alarm is
output if the number lies outside a tolerance band that can be selected.
Commissioning
"Monitoring tolerance band, pulse number" is activated with p0437.2 = 1.
The upper and the lower limit values of the tolerance band can be set using p4683 and
p4684. Within this tolerance band, the detected number of pulses is considered to be
correct.
Principle of operation
● After each zero mark, it is again checked as to whether up to the next zero mark the
number of pulses lies within the tolerance band. If this is not the case and "pulse number
correction for faults" (p0437.2 = 1) is parameterized, then alarm A3x422
seconds.
● If one of the limits has a value of 0, then alarm A3x422
● Display of uncorrected encoder pulses
For p0437.7 = 1, the number of corrected pulse errors is displayed in r4688 with the
correct sign.
When p0437.7 = 0, the number of corrected missing pulses per zero mark distance is
displayed in r4688.
For a drift after one revolution, if the tolerance band limit is not reached, an alarm is not
output. A new measurement is performed if the zero mark is exceeded.
● Number of pulses outside the tolerance band
If the tolerance band is violated, then in addition to alarm A3x422
r4689 = 1 is set (access level 4). This value remains for 100 ms, so that a control can
detect several violations in quick succession one after the other even for high-speed
drives.
The message bits of parameter r4689 can be sent to a higher-level controller via
PROFIBUS / PROFINET as process data.
● The accumulated correction value can be sent to a higher-level control (e.g. :
p2051[x] = r4688). The control can then set the contents of the counter to a specific
value.
Note
External encoders as leading value encoder in the drive group
The "tolerance band pulse number monitoring" also functions for external encoders, which
operate in a drive line-up as leading value encoder (monitoring the position value XIST1 from
a direct measuring system).
x = encoder number (x = 1, 2 or 3)
1)
574
1)
is deactivated.
1)
, display parameter
1)
Converter cabinet units
Operating Instructions, 11/2017, A5E36652151A
is output for 5
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