Gap Response Message Fields
The Gap Response message is sent by the GRP in response to a Gap Request message. The Unit and Sequence fields will match the values supplied in the Gap Request message. A Gap Response message, with a Status of Accepted or reason for failure, will be sent for each Gap Request message received by the GRP.
| Field | Offset | Length | Value/Type | Description |
|---|---|---|---|---|
| Length | 0 | 1 | Binary | Length of this message including this field. |
| Message Type | 1 | 1 | 0x04 | Gap Response Message |
| Unit | 2 | 1 | Binary | Unit the gap was requested for. |
| Sequence | 3 | 4 | Binary | Sequence of first message in request. |
| Count | 7 | 2 | Binary | Count of messages requested. |
| Status | 9 | 1 | Alphanumeric | Accepted or reason for reject*. |
| Total Length = 10 bytes | ||||
| Gap Response - Status Codes | ||||
| ‘A’ | Accepted | |||
| ‘O’ | Out of range (ahead of sequence or too far behind) | |||
| ‘D’ | Daily gap request allocation exhausted | |||
| ‘M’ | Minute gap request allocation exhausted | |||
| ‘S’ | Second gap request allocation exhausted | |||
| ‘C’ | Count request limit for one gap request exceeded | |||
| ‘I’ | Invalid Unit specified in request | |||
| ‘U’ | Unit is currently unavailable | |||
* - All non-’A’ status codes should be interpreted as a reject.