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CANFDNET-400U
High-performance Four-channel CANFD Bus-to-Ethernet Converter User Manual
Modbus RTU protocol format on the serial port side. Therefore, the converter not only
allows users to use the Modbus RTU protocol, but the converter can also directly interface
with other devices that support the Modbus RTU protocol. On the CAN or CANFD side, an
easy-to-use segmented communication format is developed to realize Modbus
communication. The role of the converter is still protocol verification and forwarding. It
supports Modbus protocol transmission, not Modbus master or slave host. The user can
communicate according to the Modbus protocol.
In "transparent conversion" and "format conversion", a byte of frame information is
used to identify some information of the CAN frame, such as type, format, and length.
Table 4.1 lists the frame information format.
FF
RTR
0: Standard
0: Data
frame
frame
1: Extended
1: Remote
frame
frame
4.1 Transparent Conversion
In transparent conversion mode, the converter receives the data on one side of the
bus and immediately converts it and sends it to the other side of the bus. In this way, the
data flow is processed, which maximizes the speed of the converter and improves the
buffer utilization. The reason is that the converter is converting and sending at the same
time as receiving, which frees up the buffer that can be received.
4.1.1
Frame Formats
1. Serial bus frame
It can be a data stream or data with a protocol. According to the user-defined CAN
type, it is decided to forward to CAN or CANFD message. The frame information and
frame ID forwarded to the CAN (CANFD) message are defined by the user in advance.
2. CAN (CANFD) bus frame
The format of CAN (CANFD) message frame remains unchanged. The frame
information and frame ID need to be enabled by configuration, that is, whether to forward
the frame information and frame ID to the serial frame.
4.1.2
Conversion Methods
In transparent conversion mode, CAN and CANFD messages are converted in
roughly the same way. The main difference is that a CANFD message can be converted
into more serial frame data.
1. Serial frame to CAN (CANFD) message
All the data of the serial frame is sequentially filled into the data field of the CAN
(CANFD) message frame. The converter receives and converts data as soon as it detects
Table 4.1 Frame format
EDL
BRS (CANFD valid)
0: CAN
0: Disable acceleration
1: CANFD
1: Enable acceleration
©2021 Guangzhou ZLG Microelectronics Technology Corp.,Ltd.
17
User Manual
L3
L2
L1
The length of the identification
data is equivalent to the DLC
L0
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