ABBAC 800M PROFIBUS DP Configuration

enabled, the DPM1 switches the outputs of all assigned slaves to a fail-safe state the 

moment a slave is no longer ready for user data transmission. The DPM1 

subsequently switches to the clear state. If this parameter is disabled, the DPM1 

retains in the operate state even in the event of a fault and the user can control the 

reaction of the system. Please refer also to Settings Tab on page 49.

Sync and Freeze Mode

In addition to the normal cyclic communication between the DPM1 (DP Master 

Class 1) and the assigned slaves, a master can send the control commands sync and 

freeze via multicast to a group of slaves. 

With the sync-command the addressed slaves will freeze the outputs in their current 

state. New output values received by the master will be stored while the output 

states remain unchanged. The stored output data are not sent to the outputs until the 

next sync command is received. The Sync mode is terminated with the “unsync” 

command. 

In the same way, a freeze command causes the addressed slaves to enter freeze 

mode. In this mode, the states of the inputs are frozen at their current value. The 

input data are not updated again until the master sends the next freeze command. 

Freeze mode is terminated with the “unfreeze” command.

The CI854/CI854A does not support sync and freeze mode

Monitoring the DP-V0 Communication

The cyclic communication between the DPM1 and the slaves is monitored by the 

master and the slaves itself. 

If the CI854/CI854A master unit detects a failure in the communication with a 

slave, it will indicate the corresponding slave as disturbed. If enabled, Auto Clear 

Modus will be activated. On CI854/CI854A a special handling is implemented to 

support also redundancy for master and slave. In both cases the monitoring timings 

consider the failovers of master and slave. 

On slave side the communication with the master is controlled via the watchdog. If 

no data communication with the master occurs within the watchdog control interval, 

the slave automatically switches its outputs to the fail-safe state.

Please refer also to Connection Error on page 70

Multi Master Systems

In a multi master system several masters are connected to one bus. They represent 

either independent subsystems, comprising one DPM1 (DP Master Class 1) and its 

assigned slaves, or additional configuration and diagnosis devices. The 

CI854/CI854A master unit supports multi master systems. 

The Control Builder M with the integrated PROFIBUS master calculation does not 

support multi master configurations. The calculation only covers one 

CI854/CI854A with its assigned slaves. If you connect several CI854/CI854A or 

additional configuration devices to the same bus you have to adapt the bus settings 

manually. But only the TTR has to be adapted. An overall TTR has to be calculated 

as the sum of all individual TTR for the CI854/CI854A master units connected to 

the same PROFIBUS. The resulting TTR has to be manually configured for all 

connected CI854/CI854A master units. 

Example: you have three CI854/CI854A master units having the automatically 

calculated TTR times 20.000, 30.000 and 40.000, then you have to manually 

configure the TTR time 90.000 for all three units. 

If a standalone tool is directly connected to the PROFIBUS as DPM2 (DP Master 

Class 2) master for some acyclic communication, then the TTR time of this 

master also has to be taken into account. Otherwise the standalone tool might get 

communication problems

Acyclic Data Communication

The key feature of version DP-V1 is the extended function for acyclic data 

communication. The acyclic data communication is mainly used for configuration 

and parameterization purpose. With the acyclic DP-V1 read and write services the 

master can read or write any desired data to and from the slave. The data is 

addressed by slot, index and length. Each data block can be up to 244 bytes.

Figure 3. Acyclic Communication in DP-V1: Read Service

The transmission of acyclic data is executed in parallel to the cyclic data 

communication, but with lower priority. Acyclic services are operated in the 

remaining time at the end of the DP-V0 cycle. 

The automatic master calculation for CI854/CI854A ensures that the gap on 

PROFIBUS is big enough for some acyclic communication. If there is a need to 

increase the gap for some additional acyclic communication this can be done via the 

TTR time. Please refer also to Settings Tab on page 47.

Alarms and Status Messages

As a further function in DP-V1, the device specific diagnosis of the DP-V0 have 

been enhanced and divided into the categories alarms and status messages. As the 

major difference to the DP-V0 diagnosis, the alarms from the slave to the master are 

transferred via confirmed services. 

Redundancy

Overview

With PROFIBUS and CI854/CI854A you have a high scalability for redundancy. 

You have the options to configure redundancy for: