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62 Fieldbus interface
6 Operation IL•1F CANopen DS301
0198441113586, V2.01, 11.2008
6.2.2 Reading a parameter
Task The parameter Status.n_act, 31:9 (actual speed) is to be read.
Index and subindex must be converted to hexadecimal notation and the
constant 3000
h
added to the index for the SDO access:
• Index:31 = 1F
h
+ 3000
h
= 301F
h
• Subindex 9 = 09
h
The value "40
h
" must be entered as the CCD. This value identifies a
"Read Request".
Transmit data
The 4 data bytes have no significance for a read request.
Receive data
The product transmits the data as 32 bit values back to the master (CCD
is "43
h
"). It also sends back data as a 32 bit value which are described
as INT16 or UINT16 data types in the product manual. When an INT16
or a UINT16 value is read, it is therefore possible to evaluate all 4 data
bytes. However, for 16 bit data it is also correct to evaluate only the first
two data bytes and to ignore the last two data bytes.
6.2.3 Synchronous errors
Receive data with error frame "Error
Response"
If an SDO write or read command fails, the product responds with an er-
ror frame "Error Response". This may happen if, for example, you try to
read or write a non-existent object. The transmitted error number pro-
vides information on the exact cause.
The example shows the response to a write or read request for a non-
existent object 40:32.
The error number of a synchronous error message is stored as a
UINT16 value and the corresponding CCD (Error Response) is as-
signed the value 80
h
. Refer to 7.3.2 "Error code table" for a table with the
error numbers.
Object COB ID CCD Idx Sdx Data Description
Tx 301F
h
:09
h
Sta-
tus.n_actT
600
h
+ID 40
h
1F
h
30
h
09
h
XX XX XX XX Reads the actual speed. The data
has no significance.
Object COB ID CCD Idx Sdx Data Description
Rx 301D
h
:09
h
Status.n_act 580
h
+ID 43
h
1F
h
30
h
09
h
E8 03 00 00 The data 000003E8 corresponds
to 1000 min
-1
.
Object COB ID CCD Index Sub Data Description
Rx 3028
h
:20
h
580
h
+ID 80
h
28
h
30
h
20
h
00 00 02 06 Error value 06020000h means
"object does not exist in object dic-
tionary"