Danfoss MCO 305 Design Manual page 186

MCO 305 Design Guide
CAN Basic library
Raw Telegram mode
This library contains all the functions necessary to do raw CAN telegram transfer. So you can define
mailboxes with the commands DEFCANIN and DEFCANOUT for reading and writing telegrams. Those
commands allow the length and telegram id (standard 11 bit identifiers) to be chosen. Once defined, you
can use those mailboxes to receive and send those telegrams using the commands CANOUT and CANIN.
The CANIN command allows the user to use remote frames and to define if he wants to wait for an answer
or not. You can also define the time out for the reading.
The command CANDEL can be used to delete already defined mailboxes.
Command Description
CANDEL erases all or single
CAN objects
CANIN reads an object
CANOUT sends message
(active)
DEFCANIN defines a receive
object
DEFCANOUT defines a transmit
object in the CAN
controller
Buffered Message Transfer
This message transfer is used by APOSS. But if APOSS is not active, it could also be used for application
purposes. But you must be aware that buffered message handling expects that all telegrams are really read.
Otherwise, a full buffer can stop program execution because, for example, an OUTMSG has to wait until
buffer allows writing again.
There are three telegrams used for this sort of communication.
GlobalMessage telegram ID = 0
RxMessage telegram ID = CANNR * 2 + 1 8 Byte length
TxMessage telegram ID = CANNR * 2
GlobalMessages are read by all controllers. The first two bytes may not be used by applications. These bytes
must always be 0 or you may have unwanted side effects.
186
__ How to Program __
Syntax
CANDEL objno
status = CANIN objno
timeout control varhi
varlo
CANOUT no valhi vallo
objno =
DEFCANIN id dlen
objno = DEFCANOUT id
dlen
8 Byte length
®
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Parameter
objno = object number, which is returned during
object definition
= –1 deletes all objects (except standard objects)
objno = object number, which is returned during
object definition
timeout = -1 = no wait for data
0 = waits until data arrives
>0 = waits for data in timeout
control =
0 = copies new arrived data to the variables
1 = sends a remote frame and waits for data in
dependence on timeout
varhi = bytes 0 to 3 of the CAN object data
varlo = bytes 4 to 7 of the CAN object data
valhi = bytes 0 to 3 of the CAN object data
vallo = Bytes 4 to 7 of the CAN object data
id = CAN-id
dlen = data length of the object in bytes (max.
8 bytes)
id = CAN-identification number
dlen = data length of the object in bytes (max.
8 bytes)