Campbell Hausfeld SDM-CAN - Manual (Page 52)

SDM-CAN CAN-Bus Interface User Guide
On receiving the frame data from the datalogger the SDM-CAN will convert and
shift the data into the correct position and then place it into the read buffer which
is set as a 64 bit frame. Depending on your program, you could then continue to
build a frame or decide to transmit it onto the CAN-Bus. If you have completed
the building of a frame then you have the choice to either transmit it onto the
CAN-Bus or set it up as a Remote Frame Response. For the transmitted frames,
the SDM-CAN will set a flag in the buffer to indicate new data is ready for
transmission. The SDM-CAN will scan the buffers, checking this flag in each
buffer that is set for transmission. When it finds a flag that is set, it will first check
if the transmitter is busy, and if it is will wait until it is free. The frame will then
be transferred to the transmitter which will transmit it onto the bus. Finally the
transmit data flag will be cleared.
When a frame is set up for a remote frame response, the frame is transferred into
the working buffer ready for reception of a Remote Frame Request. When a
Remote Frame Request is received, and is accepted as a valid frame, the
SDM-CAN will find the relevant buffer, and will then set the data transmit flag.
From then on it will follow the normal frame transmission protocol as described
above.
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