Bosch rexroth NYCe 4000 Hardware Manual page 172

NYCe 4000 Multi-axis motion control system Hardware Sys‐
tem Manual
The analog to digital conversion for the analog input value needs a certain
amount of time. The PVL calculation on the drive module is started before the
conversion is finished. The transmission of the sync packet is also started
before the conversion is finished. For these reasons, the PVL on the drive
and the PVL on the MCU both use the analog input value of the previous
PVL cycle.
As the acquisition and calculation of the position information of the digital
encoders (MSM, Sanyo Denki, or EnDat2.2) requires more time than
available when the PVL executes at 32 kHz, the use of a digital encoder puts
a limit on the highest selectable PVL frequency. The PVL frequency must be
set lower to meet the requirement that the position information used by the
PVL is the actual position.
● For MSM incremental and absolute encoders the allowed maximum
PVL frequency is 4 or 8 kHz.
● For Sanyo Denki absolute encoders the allowed maximum PVL
frequency is 4 or 8 kHz.
● For EnDat2.2 encoders the allowed maximum PVL frequency depends
on the EnDat clock, see
EnDat2.2 encoder clock frequency" on page
EnDat clock frequency
1 MHz
2 MHz
4 MHz
Tab. 13-3: Maximum PVL frequency vs. EnDat2.2 encoder clock frequency
For more information see the NYCe 4000 Tools Manual, NYCeConfigurator
chapter, "Configuration at the axis level".
Digital inputs and digital outputs
The hardware inputs (such as digital inputs and temperature sensor) are
always up-to-date in the sync packet. The digital I/O operations are started
on the latch pulse. Sampling the digital inputs or triggering the digital outputs
requires a negligible amount of time, less than 2 µs.
The motor current is measured by the PVL. The sync packet contains the
measured motor current of the previous PVL cycle.
Relation between PVL update and setpoint generator
The setpoint generator calculates every MCU sample a new setpoint. To
minimize the disturbance in the closed loop the calculated displacement is
"spread" over the PVL cycles executed during the MCU sample period. Thus,
if the MCU sample frequency is 8 kHz and the PVL frequency is 32 kHz, the
displacement is divided in 4 smaller displacements, see
between MCU sample (setpoint generator) and PVL sample" on page
tab. 13-3 "Maximum PVL frequency vs.
163.
Maximum PVL frequency
4 kHz
8 kHz
16 kHz
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Encoders
fig. 13-6 "Relation
164.