PM
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3133i User
’s Manual v1.02
Last Revised: Apr. 2023 Page: 40
Copyright © ICP DAS Co., Ltd. All Rights Reserved.
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8.2 CANopen Protocol
The CANopen is a kind of network protocols evolving from the CAN bus, used on car
control system in early days, and has been greatly used in various applications, such as
vehicles, industrial machines, building automation, medical devices, maritime
applications, restaurant appliances, laboratory equipment & research.
8.2.1 SDO Introduction
8.2.1.1 Upload SDO Protocol
Initiate SDO Upload Protocol
Before transferring the SDO segments, the client and server need to communicate with
each other by using the initiate SDO upload protocol. Via the initiate SDO upload
protocol, the SDO client will inform the SDO server what object the SDO client wants to
request. As well, the initiate SDO upload protocol is permitted to transmit up to four
bytes of data. Therefore, if the data length of the object, which the SDO client can read,
is equal to or less than the permitted data amount, the SDO communication will be
finished only by using the initial SDO upload protocol, i.e. if the data upload is less
enough to be transmitted in the initiate SDO upload protocol, then the upload SDO
segment protocol will not be used. The communication process of this protocol is shown
as follows.
ccs
: client command specified
2: initiate upload request
