Omron CJ1W-PRT21, Operation Manual

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1 Features and System Configuration
1-8
CJ-series PROFIBUS Slave Unit Operation Manual for NJ-series CPU Unit (W510)
PROFIBUS-DP provides effective protection functions against parameterisation errors or failure of the
transmission equipment. Time monitoring is provided at the master and at the slaves. The monitoring
interval is specified during the configuration.
 Monitoring at the Master
The DPM1 master monitors data transmission of its active slaves with the Data_Control_Timer. A
separate control timer is used for each slave. This timer expires when correct data transmission
does not occur within the monitoring interval.
If the master’s Auto_Clear mode is enabled, the DPM1 exits the Operate state, switches the outputs
of all assigned slaves to fail-safe status and changes to its Clear state (see
1-2 Configuring the
CJ1W-PRT21 Slave Unit ).
 Monitoring at the Slave
The slave uses the watchdog control to detect failures of the master or the transmission line. If no
data communication with the master occurs within the watchdog control interval, the slave automati-
cally switches its outputs to the fail-safe status. This mechanism can be enabled or disabled for
each individual slave.
Also, access protection is available for the inputs and outputs of the DP slaves operating in multi-
master systems. This ensures that direct access can only be performed by the authorised master.
For other masters, the slaves offer an image of their inputs and outputs, which can be read by any
master, even without access rights.
PROFIBUS-DP distinguishes four different network states.
 OFFLINE
Communication between all DP participants is stopped.
 STOP
Communication between DPM1 and DP slaves is stopped. Only communication between DPM1
and DPM2 is possible.
 CLEAR
DPM1 master attempts to set parameters, check the configuration, and subsequently perform data
exchange with its associated DP-slaves. The data exchange comprises reading the inputs of the
DP-slaves and writing zero’s to the outputs of the DP-slaves.
 OPERATE
DPM1 master exchanges data with its assigned slaves, inputs are read and outputs are written.
Beside this, the DPM1 cyclically sends its local status to all assigned DP slaves (with a multicast
message) at a configurable time interval.
1-1-8 Protection Mechanisms
Time Monitoring
1-1-9 Network Operation Modes