IFM PDM360NG Series, System Manual

Page: 170 / 463

ifm System Manual ecomat mobile PDM360NG (CR1080, CR1081, CR9042) Target V01 2011-07-28
CAN in the PDM360 Exchange of CAN data
170
9.3.2 CAN functions in the IEC user cycle
Processing of the program POUs ............................................................................................. 170
POU inputs ................................................................................................................................ 171
POU outputs.............................................................................................................................. 172
Libraries for CAN POUs ............................................................................................................ 173
7396
INFO:
IEC user cycle = PLC cycle in the CoDeSys application program.
The POUs of the external libraries are NOT executed during runtime of the IEC user cycle, but before
or afterwards. This means that the function blocks or the process variables are static during the IEC
user cycle seen from the point of view of the IEC programmer. Exempt from this are function blocks
with transmit function and FBs with FiFo function:
- CAN_TX...,

FBs for RAW-CAN (transmitting messages) ( → page 184 )
- CAN_RX_ENH_FIFO ( → page 200 )
- CAN_RX_RANGE_FIFO ( → page 196 )
INFO:
FiFo (
F
irst
I
n,
F
irst
O
ut) = operation of the stack: the data package which was written into a
stack at first will be read at first too. For every identifier there is such one buffer (as a queue) available.
In fact, CAN stacks are also executed during the IEC user cycle, for example data is still transmitted
cyclically and multi-frame messages are still received. However, they will only be provided to the
application program after the IEC user cycle has elapsed.
INFO:
CAN stack = stack of tasks for CAN data communication.
Processing of the program POUs
8352
Controlled processing of the program POUs
is important. The operating system ensures the
following order:

CAN_ENABLE

J1939_ENABLE

CANopen_ENABLE

automatic start of the CANopen network based on the corresponding selection in the development
environment

update process image for J1939 and CANopen

other function blocks
Thus, when e.g. setting the baud rate a defined state on a system is achieved.
The baud rate which has been chosen for CAN_ENABLE is not supposed to be changed anymore by
any of the subsequent calls.
If CAN_ENABLE is set to FALSE and the CAN channel is thereby deactivated, all protocols will also
be reset.