ProSoft Technology ProTalk PTQ-PDPMV1 User Manual page 197

PTQ-PDPMV1 ♦ Quantum Platform
PROFIBUS DP Master Network Interface Module for Quantum
Remote (passive) Master operational prior to active
As soon as the remote (passive) Master is ready to communicate on the
PROFIBUS network, it would start sending ping messages to the local (active)
one. As soon as the local (active) Master responds, the COM-bit is altered from
zero to one.
Remote (passive) Master failure
When the local (active) Master has not received any ping messages from the
counterpart within TA, it would clear the COM-bit. This scenario would also apply
when the field bus link between the two Masters is lost, due to a cable break, for
example.
ProSoft Technology, Inc.
August 12, 2014
Hot Standby Support
User Manual
Page 197 of 306