UM-0086-A2
CANgate User’s Manual
Page 12
Using CANgate
Memory Slots
By default, CANgate will not send or receive any CAN messages. In order to do anything useful, it must first be programmed.
CANgate is programmed by sending commands to set up one or more
memory slots
. Each memory slot can be configured
to perform one of the following functions:
Slot type
Class
Action
RECV
RECVE
passive
receive CAN messages with a specified
identifier
value, extract the specified data field and return
its value as a formatted ASCII value
RECVJ
passive
receive CAN messages relating to a specified
J1939 PGN
number, extract and return the
specified data field
GPS
passive
receive
NMEA-0183
messages of the specified sentence type, extract and return the specified
data field
SEND
SENDE
active
send a CAN message
RQST
active
request an
ISO-14230
parameter, wait for the reply, extract and return the specified data field
RQSTJ
active
request a
J1939 PGN
, wait for the reply, extract and return the specified data field
As can be seen, there are two classes of slots:
passive
and
active
.
For RECV, RECVE, RECVJ and GPS slots, CANgate passively receives all matching messages then returns the last known
data value either at a fixed rate, or when requested by the host (data logger or computer). Statistical calculations can
optionally be performed, resulting in a min/max/average value being returned instead of an instantaneous value.
For SEND, SENDE, RQST and RQSTJ slots, CANgate will take the specified action (ie. transmit a message and possibly
wait for a reply) either at a fixed rate or when requested by the host.
In all cases, one memory slot corresponds to one data value of interest. So if a particular type of CAN message contains six
separate values packed into its data area, of which four are of interest, then you would set up four memory slots – each one
configured to extract a different subfield.
Up to 150 memory slots (which are referred to by number, 1-150) can be set up. Slot configurations are automatically saved
to flash memory so that operation will automatically resume following a power interruption.
One further memory slot,
Slot 0
, is provided. This is intended to be used as a "scratch pad" for one-off requests, ie. it may be
reprogrammed many times during operation. This slot's configuration is not saved to flash.