Lenze PLC Designer PLC Designer (R2-x) CANopen for Runtime Systems - Manual (Page 27)

L-force | PLC Designer - CANopen for Runtime Systems
CANopen-Master library
26 DMS 2.0 EN 05/2009 TD29
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2.4.4.7 Guarding the configuration phase
The configuration phase of the slaves can be guarded. First of all the master must be guarded in its
boot-up phase, because it will get caught at nStatus = 3, if a non-optional slave is not found during
boot-up.
Slaves, at which a problem occurs during the configuration phase, will get caught at nStatus = 3 or will
directly change to error state > 5 after the configuration phase.
The following examples show application code which can be used to keep working with the CAN
network even in certain situations resp. to get diagnosis information.
During the guarding of the boot-up phase it must be regarded that per IEC-cycle of the task, which
calls the CANopen-Master (also see implicit calls), only one SDO can be transmitted to each slave.
That is, the boot-up phase might take long time, depending on the maximum number of SDOs which
must be transferred to a slave.
2.4.4.7.1 Access on the state of the CANopen-Master
In order to avoid that application code is processed although the IO-network is not yet ready, the
status of the master must be polled:
IF pCanOpenMaster[0].nStatus = 5 THEN
<application
code>
END_IF
2.4.4.7.2 Time guarding in the boot-up phase
VAR
Guarding : TON;
iSlave : INT;
bSlaveFound: BOOL;
END_VAR
Guarding(IN:= pCanOpenMaster[0].nStatus < 5, PT := T#10 );
IF Guarding.Q THEN
(* figuring out whether there is a non-configurable slave *)
FOR iSlave := pCanOpenMaster[0]. nFirstNodeNr TO pCanOpenMaster[0]. nLastNodeNr
DO
IF pCanOpenNode[iSlave]. nStatus < 4 THEN
bSlaveFound := TRUE;
EXIT;
END_IF
END_FOR
END_IF
After this sequence in variable iSlave the number (index) of the fist slaves appears, which is still in
status 3 after expiration of the guarding time.
This example only is valid for a non-optional slave. Optional slaves must be managed by the
application, because it is not always recognizable, whether they are available or not. The startup
phase will be validated as “OK” even if optional slaves are not available.