GridConnect CAN USB-232, User Manual

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Troubleshooting
2-24 CAN USB-232 User Manual
The SJW parameter controls the maximum allowable adjustment to the sampling point. This allows for a
CAN node to adjust its sampling point when it determines that the sample point would be too early or too
late. By setting the SJW field to a large number, the CAN USB-232 can work with other nodes with a large
variation is bus oscillator tolerances. The value can range from 1 to 4.
2.7 CAN Command Mode
In the command mode, the CAN USB-232 is capable of sending and receiving arbitrary CAN messages via
the use of ASCII or Binary formatted message strings (Figure 3).
Figure 3
When the CAN USB-232 receives a valid ASCII message string, it converts it to a CAN message and
transmits it out over the CAN network.
Conversely, when a CAN message is received by the CAN USB-232, it converts it to an ASCII message
string and transmits it out of the serial port.
The CAN USB-232 supports ten (10) CAN receive message filters consisting of STD, EXT, STD-RANGE,
or EXT-RANGE. By using the masks to specify which bits of an identifier are to be compared to the filter
value, the CAN USB-232 is capable of selecting an arbitrary sub-set of the total possible CAN messages
and rejecting all others. Thus, only desired messages will be received and the total required bandwidth of the
serial link is kept to a minimum.
In order to facilitate human CAN network monitoring, there is an option to append a CR/LF sequence to
each output ASCII message string. Doing so makes it much easier to watch the incoming messages on a
terminal where each message is on a separate line. See
Set CAN Command Mode Message Output
Termination on page 2-31.