Baud rate
Before starting the Bus Coupler, its baud rate has to be set.
BK5110, BK5120 and LC5100
This setting is made by means of the DIP switch on the coupler.
The baud rate is set with switches 7 and 8.
The following table shows the possible baud rate settings.
|
Baud rate |
DIP7 |
DIP8 |
|---|---|---|
|
Auto |
0 |
0 |
|
500 kbit/s |
1 |
0 |
|
250 kbit/s |
0 |
1 |
|
125 kbit/s |
1 |
1 |
BK5150 and BK5151
These Bus Couplers have no switch for the baud rate. Their default setting is auto baud rate.
Auto-Baud-Rate
Switch setting (0/0) activates the auto baud rate function (from firmware version B7). In order for automatic baud rate detection to function, it is necessary for a number of valid telegrams to be present on the bus at the desired baud rate. The RUN and CAN ERR LEDs blink in rapid alternation while the baud rate search is in progress. As soon as a baud rate has been detected and adopted, the Fieldbus Box begins initialization.
A software reset does not lead to a new baud rate search. The previously active baud rate is maintained.
Bit Timing
The following baud rates and entries in the bit-timing register are supported by the Beckhoff CANopen devices:
|
Baud-rate [kbaud] |
BTR0 |
BTR1 |
Sampling Point |
|---|---|---|---|
|
1000 |
0x00 |
0x14 |
75% |
|
800 |
0x00 |
0x16 |
80% |
|
500 |
0x00 |
0x1C |
87% |
|
250 |
0x01 |
0x1C |
87% |
|
125 |
0x03 |
0x1C |
87% |
|
100 |
0x04 |
0x1C |
87% |
|
50 |
0x09 |
0x1C |
87% |
|
20 |
0x18 |
0x1C |
87% |
|
10 |
0x31 |
0x1C |
87% |
The bit-timing register settings given (BTR0, BTR1) apply, e.g. for the Philips 82C200, SJA1000, Intel 80C527, Siemens 80C167 and other CAN controllers. They are optimized for the maximum bus length.