Are currently trying to use CANopen with a device and have done some
development. Have until now run hard coded mappings
but now reached a point there configuration is needed. Implement graphical
configuration and store configuration in
binary format would of course be one option but have chosen a text file
possible to edit manually. Use maps like below.
map={.cobId=181h, .name="encoder.cnt", .dir=HAL_OUT, .type=HAL_S32, .bitlen=32,
.bitpos=32, .name_scaled="encoder.pos",
.name_gain="encoder.pos.scale", .gain=0.13}
map={.cobId=201h, .name="pos.cnt", .dir=HAL_IN, .type=HAL_S32, .bitlen=32,
.bitpos=0}
First field is message "identifier" for the messages on the network. Second is
name of hal pin. Third is hal direction.
Fourth is hal datatype. Fifth is length of number in message which may be one
for a single bit. Sixth to eigth is
optional, if availabe it is name of hal pin for scaled value. Seventh if
available is name of hal parameter for scaling
gain. Eigth if available is gain default value. There is probably a need to add
one parameter before the first to
identify network in case several are available.
This should work for CANopen both over CAN networks but also over Ethercat but
are a little bit unsure about how to
identify the message if used over Ethercat. CAN network use rather small
messages 8 bytes maximum for ordinary CAN and
some order of magnitude larger for CAN FD, all variables in same message same
direction. Ethercat use much larger
messages and may have both inputs and outputs in "same" message, message is
sent in a ring similar principle as cascaded
shift register so outputs is written in message before sent while inputs are
read from message then it arrive back. Need
for mapping is same so should hovewer be possible to use same syntax in
configuration file.
Syntax in configuration file is currently more or less as an array in C as I
copied the hard coded mappings from C to
configuration file. Have a simple first far from perfect implementation or hack
that read the mappings from the
configuration file. Anybody have any suggestions about the syntax for the
configuration file? There is some more or less
standard to write down these kind of mappings for CANopen I have missed? Any
parser in Linuxcnc which may be reused to
read this configuration file possible with other syntax?
There is also sometimes a need for a "configuration script" before nodes enter
mode of operation normal. First idea is
to borrow the CANopen CiA309-3 standard and simply enter the command(s) in a
file, possible same file as used for the
mapping. Anybody have any other suggestion?
Regards Nicklas Karlsson
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