sdo - CANOpen SDO objects for MultiCAN¶
Introduction¶
The sdo protocol implements CANOpen conform sdo objects for MultiCAN.
Device Support¶
sdo currenty has device support for longin and longout records.
To use sdo, set field DTYP to SDO.
The SDO object is specified in the link field INP or OUT.
These are the properties that have to be specified:
Property |
Value |
Meaning |
|---|---|---|
Server-Flag |
“Server” or “Client” |
Specifies if the IOC is a SDO server or a client |
port |
an integer |
the port on the CAN bus card |
node |
an integer |
the CANOpen node number of the IOC |
index |
an integer |
the index of the SDO object |
subindex |
an integer |
the subindex of the SDO object |
datasize |
an integer |
the size of the data transferred in bytes |
conversion-flag |
“integer” or “raw” |
specifies if an endianess conversion is done (“integer”) or the data is left unchanged (“raw”) |
timeout |
an integer |
the timeout of the SDO object. If no reply is received to an request in that time a MultiCAN timeout error is raised. |
Link specification¶
The link field string must start with a ‘@’ character.
The link consists of a number of single character field specifiers followed by a colon and a value. All fields have to be in the order shown below. None of the fields may be omitted. Note that the address is given either in decimal or in hexadecimal format, not both at the same time. These are the field specifiers:
name |
character |
meaning |
|---|---|---|
client/server flag |
C |
specifies if the IOC is a SDO client or server |
decimal address |
A |
specifies the SDO address information, port and node number, index and subindex |
hexadecimal address |
X |
specifies the hexadecimal SDO address information, port and node number, index and subindex |
value specifier |
V |
specifies the value’s size and type |
timeout specifier |
T |
specifies the timeout |
These are the values for the client/server flag:
client/server flag |
|
|---|---|
value |
meaning |
S |
server |
C |
client |
The address is specified by a list of 4 numbers which are separated just by commas, not spaces. The elements of this list are:
address specification |
|
|---|---|
number in the list |
meaning |
1 |
port |
2 |
node |
3 |
index |
4 |
subindex |
The value specifier ist consists of two comma separated values, a number, which is the datasize and a conversion flag.
value specification |
|
|---|---|
number in the list |
meaning |
1 |
size in bytes |
2 |
conversion flag |
These are the conversion flags known:
conversion flag |
|
|---|---|
value |
meaning |
R |
raw, no re-ordering of the bytes |
I |
integer, reorder bytes to CAN bus byte order and back again |
Link specification examples¶
Here is an example with a decimal address specification:
@C:S A:8,127,32765,126 V:4,R T:50000
This link specifies a SDO server on port 8, node 127, index 32765 and subindex 126. The value has a size of 4 bytes and is of type raw. The timeout is 50000 milliseconds.
Here is another example with a hexadecimal address specification:
@C:C X:2,6,1A02,A V:2,I T:3000
This link specifies a SDO client on port 2, node 6, index 6658 and subindex 10. The value has a size of 2 bytes and is of type integer. The timeout is 3000 milliseconds.
