Sync

The master device can use the Sync command in the GlobalControl request telegram, which is a broadcast telegram, to synchronize the outputs of several slave devices. The slave device acknowledges a Sync command in the diagnostic data. A DP slave device starts the Sync mode when it receives a Sync control command from its assigned DP master device.

In Sync mode, the outputs of all addressed DP slave devices are frozen to their current state. During the subsequent user data transfers, new output data is stored with the DP slave devices, but the output states of the slave devices initially remain unchanged. The output data stored in the slave device is not passed to the outputs until the next Sync control command sent by the master device has been received by the slave device. A DP slave device terminates the Sync mode when it receives an Unsync control command from its assigned DP master device.