Control Field (Commands Supported)
All commands are generated by the primary station for the secondary station. Each command carries the poll indicator to request immediate response, except when sending multiple information frames.
Information frames that are concatenated have the poll indicator turned on in the last frame of the burst. The commands supported are:
| Item | Description |
|---|---|
| Information | Sends sequenced user data from the primary station to the secondary station, and acknowledges any received information frames. |
| Receive Ready | Indicates that receive storage is available and acknowledges any received information frames. This receive ready command is a supervisory command. |
| Receive Not Ready | Indicates receive storage is not available and acknowledges any received information frames. The receive not ready command is a supervisory command. |
| Disconnect | Requests the logical and physical disconnection of the link. The disconnect command is an unnumbered command. |
| Set Normal Response Mode | Requests entry into normal response mode and resets the information sequence counts. The setnormal response mode command is an unnumbered command. |
| Test | Solicits an echoed TEST response from the secondary station and can carry an optional information field. The test command is an unnumbered command. |
| Exchange Station Identification | Solicits an exchange identification (XID) response that contains either the station identification of the secondary station or link negotiation information that allows the alteration of the primary or secondary relationship by the user. The exchange station identification command is an unnumbered command. |