User`s guide

3: BSC 3270 DLI Functions
DC 900-1340I 61
a link after issuing a Stop Link command (Section 3.4.1.6). After receiving this com-
mand, the BSC 3270 software turns on the DTR modem control signal and prepares the
link to transmit and receive data according to the current configuration settings. After a
link starts, data transmission can begin on the line.
For blocking I/O, a successful Start Link command returns zero, but you must call
dlRead to receive the DLI_PROT_RESP_BIND_ACK response indicating that the BSC 3270 soft-
ware has received a data set ready (DSR) signal from the remote end. The link is not
considered started until this signal is received; however, DSR can be ignored by using
certain settings of the modem control option (Section 4.14 on page 95). If you are using
non-blocking I/O, you must also make a
dlPoll request to read the completion status of
the command.
An unsuccessful Start Link command can return one of the following error codes in the
dlRead pOptArgs.iICPStatus field (see Appendix D for error handling):
DLI_ICP_ERR_LINK_ACTIVE
The link is already started.
DLI_ICP_ERR_BAD_MODE
The function request is not available for the requested
access mode.
DLI_ICP_ERR_BAD_PARMS
The parameter value(s) used for the function call are
illegal.
3.4.1.6 Stop Link Command
Use the dlWrite function with the pOptArgs.usProtCommand field set to
DLI_PROT_SEND_UNBIND and the pOptArgs.usICPCommand field set to DLI_ICP_CMD_UNBIND to
stop a link without ending your session with Freeway. This command turns off the DTR
modem control signal and shuts down the link transmitter and receiver. A Stop Link
command can be sent to a link that is active or already inactive.
A call to dlClose (described in the Freeway Data Link Interface Reference Guide) also
stops the link, but terminates the session as well. This is the normal method to termi-