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Appendix D
Baud rate configuration via Unit settings
The standard CANopen baud rates are selectable via the DIP-switches at the front of the Unit (see section
3-1-4). However, if a different baud rate is required, it is possible to configure this via the Unit settings. The
Unit settings only overrule the DIP-switch settings when all the configured values are within the specified
ranges. By default, these Unit settings are zero and therefore the DIP-switches determine the baud rate.
The Unit settings are made in a dedicated DM area. Refer to section 4-2-3 for the relationship between the
Machine Number and the location of the dedicated DM area.
The DM settings directly configure the hardware registers of the CAN interface that determine the baud rate.
Incorrect settings will cause improper functioning of the CAN interface. Users with little CAN experience are
advised to contact their distributor to assist in setting the correct values.
The table below lists the DM words for configuration of the baud rate.
DM word
Value
Meaning
m+16
0000 ~ 0063
BRP value
The Baud Rate Prescaler value determines the length of the time quanta
within one bit time.
m+17
0000 ~ 0003
SJW value
The (Re)Synchronisation Jump Width defines the maximum number of time
quanta a bit time may be shortened or lengthened by one resynchronisation.
m+18
0002 ~ 0015
TSEG1 value
TSEG1 is the time segment within a bit time before the sample point.
m+19
0001 ~ 0007
TSEG2 value
TSEG2 is the time segment within a bit time after the sample point.
8 000
Baud rate =
(BRP + 1) x (3 + TSEG1 + TSEG2)
[kbit/s]
Recommended:
TSEG2
≥
SJW
TSEG1 > TSEG2
TSEG1 + TSEG2
≥
5
The following table lists the values of BRP, SJW, TSEG1, and TSEG2 for the standard CANopen baud rates
that can be selected with the DIP-switches.
Baud rate (kbit/s)
BRP
SJW
TSEG1
TSEG2
10
0049
0000
0012
0001
20
0024
0000
0012
0001
50
0009
0000
0012
0001
125
0003
0000
0012
0001
250
0001
0000
0012
0001
500
0000
0000
0012
0001
800
0000
0000
0006
0001
1000
0000
0000
0004
0001
Summary of Contents for C200HW-CORT21-V1
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