Initial value for LogonRequest.HeartBtInt is set from OnixS::Eurex::Trading::HandlerSettings::sendingTimeoutMs.
Heartbeat interval 0 means that gateway will not take any action for skipped heartbeats (only allowed for non-production environments). If the value is not set, gateway will define the heartbeat interval.
When LogonResponse is received the Handler sets connection's receive data timeout according to the following formula:
Handler.HeartBtInt = LogonResponse.HeartBtInt + LogonResponse.HeartBtInt / 100 * HandlerSettings.ReasonableTransmissionTime
In this formula OnixS::Eurex::Trading::HandlerSettings::reasonableTransmissionTime is used to allow users adjust heartbeat interval according to their requirements.
Timeout for data send will be set exactly to the value of LogonResponse.HeartBtInt without any modifications.