
4.BUILDING A SAFE SYSTEM OPERATION B-62924EN/04
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4.1 SYSTEM SAFETY
The PROFIBUS-DP Master function manufactured by FANUC is
designed so that all DI signals are set to 0 when communication is not
performed normally. For this reason, to enable or disable a function
with a DI signal, build the system so that the system continues to
operate safely when the signal is set to 0.
PROFIBUS-DP communication employs a master-slave
communication mode. For this reason, ensure that the master station
always monitors the status of each slave to ensure safe system
operation.
For example, the master station can read and check the diagnose data
for each slave station to determine whether communication with the
slave station is being performed normally. A check method with using
no diagnose data is also supported. A signal for indicating normal
communication is provided in DI/DO data to be exchanged, and is
monitored to determine whether communication between the master
station and a slave station is performed normally.
As described above, for the master station, provide safety provisions
to ensure that the system is not started or is stopped safely if the
system is not ready for execution or if an error occurs in the system.
CAUTION
I/O data is not transferred in sync with ladder
execution, so that the concurrency of I/O data is not
guaranteed.
Table 4-1 indicates information about the processing to be performed
for the major communication states in the FANUC master station. By
referring to Table 4-1, build a safe system.