Notification of Status Codes

Each attempt at communication between an application program and a ZCOM terminal has a status code associated with it. The status code may be associated with a request to send a message to a terminal ZLU, to read a message from a terminal ZLU, to change the state of a terminal ZLU, or it may be an unsolicited report of a terminal ZLU status change.

For a terminal write message or a status change request, the method by which an application program is advised of the status of a terminal operation depends on the 'mode' parameter used in the calls to zsend() or zcntl() (see chapter on ZCOM C I/F Library Routines). The status will either be returned on the application program's primary ZLU for modes ZcMODE_RPT_ERRS(1) to ZcMOD_DEF_STATUS_WBUF(7), or immediately in the returned status of the call for mode ZcMOD_WAIT(8).

The status of read messages from a terminal, and unsolicited terminal status change notifications, will be sent by the ZCOM system to the program ZLU which has been designated as the receiver for the terminal (using the zset_rcvr() call mode ZcNORMAL(0)).

For a zport() call, the caller is suspended until the request is completed. The status is passed back in the status parameter on return.

All of the status codes and their defines can be found in the include file /opt/acc/include/zcom/zcomstatus.h.