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3-12 CAN232 FD User Manual
3.1.1.3 Report Error Status Message
A Report Error Status message indicates changes in the current CAN bus error status detected by the CAN
controller. This message is only transmitted if the
report err feature is enabled under the command
settings. By default this feature is disabled.
Report CAN Error Status Message Syntax
: <E> <A | W | P | B> ;
The first character ,‘:’, is for synchronization and allows the receiver’s parser to detect the beginning of a
command string.
The character ‘E’ indicates that this is a Report Error Status message.
The following character represents the new CAN error status.
‘A’ – Active (actively flagging errors on the bus, CAN operation is normal)
‘W’ – Warning (error count above the warning threshold)
‘P’ – Passive (only passively flagging errors on the bus, too many errors detected)
‘B’ – Bus Off (no longer transmitting on the CAN bus)
The terminating character ‘;’ signals the end of the message.
3.1.1.4 Appending CR/LF To Received Command Strings
When using the CAN232 FD to view received CAN messages directly on a terminal, the user can set a
configuration parameter to append a <CR> <LF> sequence to each message string generated. This makes it
easier for the user to see each received message as each message will be on a separate line. See the
eol
option under the command settings.
3.1.1.5 Timestamp
Outgoing serial command messages can have a 16-bit time-stamp appended to them with a 1-ms resolution.
In ASCII mode, the timestamp is appended to the data block in uppercase HEX ASCII in the same way that
the data field is presented (i.e.: two ASCII HEX digits to represent a byte). The '@' character is inserted
between the last DATA digit and the first TIMESTAMP digit to differentiate between the two fields.
Zero-length messages appear as they would normally, except the prefixed timestamp is added.
Ex 1:S12N12@F00F: This is a 11-bit identifier with 1 data byte and timestamp of $F00F ms.
Ex 2:X13N@2EDF: This is a 29-bit identifier with 0 data bytes and timestamp of $2EDF ms.
Ex 3:S14R5@15E5: This is a 11-bit identifier with RTR=5 and timestamp of $15E5 ms.
3.1.2 Binary Formatted Messages
Transmitting CAN messages over the serial line in binary is more efficient because the data can be
transmitted as-is without converting each byte to two ASCII characters in hex. However, it’s also a little
more complicated to frame the message since any binary value that marks the start of a message may also
appear in the data. This binary protocol makes use of DLE sequences and byte stuffing to uniquely frame
messages.
A binary message always begins with the 2-byte DLE SYNC sequence $FF $00. If this sequence happened
to occur in the middle of the binary message, it would incorrectly signal to the receiver that a new message