Difference between revisions of "CANopen:CAN SDO READ"
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Latest revision as of 15:10, 26 August 2014
In order to communicate with a specific slave we use its address and the functions CAN_SDO_READ, CAN_SDO_WRITE.
To read data from the slave we have to specify a SDO index and a sub-index.
The first sub-index is 0. If only one sub-index exists, we still have to specify 0 (we cannot omit this field).
The read value is returned from the function and can be set to a variable.
Input
Slave address, SDO index, SDO sub-index.
Output
None
Return Value
Value that is read from the slave.
Declaration
public function CAN_SDO_READ(byval slaveaddres as long, byval index as long, byval subindex as long) as long
Syntax
retVal = CAN_SDO_READ(<Slave address>, <SDO index>, <SDO sub-index>)
Limitations
Signed 8 and 16 bit objects are not properly converted to LONG.
For example 8-bit negative value, eg. -3, read as 253.
Application shall apply sign extension for negative 8/16 bit objects.
Exceptions
Examples
retVal = CAN_SDO_READ(2, 0x6041,0) ' Read status word