The Heartbeat (tag 35-MsgType=0) message is sent at regular intervals to ensure that the connection between the client and CME Globex is in a normal state. The heartbeat interval is specified during logon in tag 108-HeartBtInt of the Logon (tag 35-MsgType=A) message. If either the client or CME Group does not send messages within the time defined in tag 108-HeartBtInt, then a Heartbeat message is transmitted. A Heartbeat message is also sent in response to a Test Request (tag 35-MsgType=1) message.
CME Group requires a heartbeat interval between 5 and 60 seconds. Intervals of less than 5 seconds are not permitted. Intervals longer than 60 seconds are not supported. The recommended value is 30 (seconds).