Communication via
CAN bus (CANopen)
MSA501
Date: 12.10.2018
Art. No. 88734
Mod. status 330/18
Page 21 of 51
Example of reading SDO parameters with normal Request/Response:
The manufacturer device name stored in object 1008h of the directory of objects is to be read
from the MSA501 with device address 1h.
Calculation of the identifier: 600h + Node-ID = 600h +1h = 601h
Command: 40h
index: 1008h
sub-index: 00h
First request (= initialization) of master from slave with node ID 1h:
COB-ID User data
Command
Index L Index H Subindex Data 0 Data 1 Data 2 Data 3
601h
40h
08h
10h
00h
x
x
x
x
Response to the request by the slave:
Calculation of the identifier: 580h + Node-ID = 581h
COB-ID User data
Command
Index LB Index HB Subindex
Data 0 Data 1 Data 2 Data 3
581h
41h
08h
10h
00h
06h
00h
00h
00h
Number of expected user data bytes: 6
Second request of master from slave with node ID 1h:
COB-ID User data
Command
Index L Index H Subindex Data 0 Data 1 Data 2 Data 3
601h
60h
08h
10h
00h
x
x
x
x
Response to the request by the slave
COB-ID User data
Command
Data 0
Data 1
Data 2
Data 3 Data 4 Data 5 Data -?
581h
03h
4Dh
53h
41h
35h
30h
31h
00h
4Dh 53h 41h 35h 30h 31h = "MSA501"
5.5
Node monitoring
5.5.1
Emergency Service (EMCY)
In the case of an error, the status of the bus subscriber is transferred via high-priority
emergency messages. These messages have a data length of 8 bytes and contain error
information.
The emergency message is transferred as soon as a sensor or communication error has
occurred or when such errors have been corrected. The cause of the error is deposited in the
error buffer (see object
1003h: Pre-defined Error Field
). An emergency object is sent only once
per error event. Removal of the cause of the error is signaled by sending an emergency
message with the error code 0000h (no error). If multiple errors have occurred and one cause
of error is removed, the error code 0000h is output as well; the persisting error status is
indicated in the error register, however.
