User`s guide

128 DC 900-1340I
BSC Programmer’s Guide
The Send Disconnect command is used to:
• reject a signon bid
• reject a signon response
An unsuccessful Signon command can return one of the following error codes in the
dlRead pOptArgs.iICPStatus field (see Appendix D for error handling):
DLI_ICP_ERR_BAD_MODE
The function request is not available for the requested
access mode.
DLI_ICP_ERR_LINK_INACTIVE
The link is stopped.
5.4.1.11 BSC 2780/3780 Poll Line with No Data Command
Use the dlWrite function with the pOptArgs.usProtCommand field set to
DLI_PROT_SET_SPECIAL_POLL to send a BSC 2780/3780 Poll Line with No Data command.
This command is used when the client computer has no data to send but wants to check
whether the remote computer is active. This command causes the BSC 2780/3780 soft-
ware to bid for the line (using ENQ). If the remote computer responds normally
(ACK0), the BSC 2780/3780 software sends an immediate EOT to terminate the session
and sends a response to the client with the
dlRead pOptArgs.usProtCommand field set to
DLI_PROT_RESP_LOCAL_ACK, and the dlRead pOptArgs.iICPStatus field set to zero (success).
If the poll was not successful, the dlRead pOptArgs.usProtCommand field set to
DLI_PROT_RESP_LOCAL_ACK, and the dlRead pOptArgs.iICPStatus field set to one of the
errors shown in Ta ble 5 –5 .
If a Poll Line command is issued (using Manager or Read mode) to a link that is busy
transmitting or receiving, the BSC 2780/3780 software does not perform the poll line
until the message in progress has completed. This ensures that data acknowledgments
are returned to the client in the proper sequence.