The Heartbeat <0> monitors the status of the communication link. The exchange will anytime send a Heartbeat if there are no message transmitted during heartbeat interval
| Tag | Field Name | Required | Comments |
|---|---|---|---|
| Standard Header | Yes | MsgType <35> = 0 | |
| 112 | TestReqID | No* | *Identifier to be returned in resulting Heartbeat if request from a Testrequest<1> |
| Standard trailer | Yes |