Can Bus Sampling Time; Number Of Controllable Drives Via Can Bus - Siemens SINAMICS S120 Commissioning Manual

1.21

CAN bus sampling time

Description
The sampling time of the CANopen communication board CBC10 can be set with the
parameter p8848 "IF2 PZD sampling time".
In the factory setting, the sampling time is 4 ms. Asynchronous message frames can be
received and sent within the period of 4 ms.
For cyclically received message frames, the cycling time must be larger than at least double
the sampling time, according to the Shannon sampling theorem.
Example:
The SYNC cycle should be 3 ms. Setting in p8848=1 ms. So the cycle time is larger than
double the sampling time.
Setting the CAN bus sampling time using p8848:
● Set the device commissioning parameter filter p0009 = 3 (drive basis configuration).
● Change and save parameter p8848.
● The changes become active immediately.
1.22

Number of controllable drives via CAN bus

Description
Depending on the request to the drive, up to 4 axes can be controlled simultaneously using
the CAN bus, where for CANopen a maximum of 4 transmit message frames and 4 receive
message frames can be used for communication. If all 8 of the maximum possible
communication message frames are used for drives, only 3 drives can be controlled -> 3 * 8
= 24.
The maximum possible number of drives is limited by
1. the demands on the drives (e.g. slave drives often need less than 8 message frames)
2. the maximum number of communication message frames, i.e 25.
The same rules apply for the number of controllable drives as for PROFIBUS – up to the
number of maximum controllable drives/axes.
Servo control
● maximum of 4 axes controllable.
Vector control
● maximum of 2 axes controllable.
CANopen interface
Commissioning Manual, (IH2), V2.6, 10/2008 Edition, 6SL3097-2AA00-0BP3
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1.21 CAN bus sampling time
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