Danfoss VACON 1000 Operating Manual page 59

VACON® 1000 Fieldbus Options
Operating Guide
5.6.2 CANopen Slave/Modbus Master
CANopen
Initiate Upload SDO
Response Upload SDO
Initiate Download SDO
Response Download SDO
TPDO
RPDO
Illustration 23: CANopen Slave/Modbus Master Communication Mode
Communication mode between CANopen and Modbus is asynchronous mode.
"Data 1" shows the data transfer process from CANopen to Modbus. "Data 2" shows the data transfer process from Modbus to CAN-
open.
TPDO and RPDO apply to producer/consumer mode, and is often used in occasions with high requirement for speed. Upload SDO
and Download SDO apply to client/server mode, the mode can guarantee safety of data, and is often used in occasions with low
requirement for speed.
The data exchange mode between Modbus and CANopen is shown in the following illustration. The data exchange buffer size is
1 kB, input buffer is 512 bytes (Modbus slave sent, gateway received), and output buffer is 512 bytes (CANopen master sent, gate-
way received).
Illustration 24: CANopen Slave/Modbus Master Data Exchange Mode
5.6.2.1 SDO Visit
Input/output buffer supports fast SDO visit, the position where input/output buffer is in the object dictionary is listed in the follow-
ing table.
Table 37: Locations of Input/Output Buffer
Index Sub-index
0x2000 0
0x2001 0
... 0
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Gateway
Request message (Data 1)
Response message
Request message
Response message (Data n)
Gateway
Input buffer
(512 bytes)
Output buffer
(512 bytes)
Description
Input No.0–No.3 byte of 512 bytes (4 bytes, readable)
Input No.4–No.7 byte of 512 bytes (4 bytes, readable)
...
Modbus
.
.
.
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CANopen