User`s guide

62 DC 900-1340I
BSC Programmer’s Guide
nate a session at the end of a client application. The Stop Link command is useful for
temporarily stopping the link without terminating the session (for example, to recon-
figure the link using the Link Configuration command). The link is restarted again by
issuing a Start Link command.
For blocking I/O a successful Stop Link command returns zero, but you must call
dlRead to receive the DLI_PROT_RESP_UNBIND_ACK response indicating the link is deacti-
vated. 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 Stop 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_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.
3.4.1.7 BSC 3270 Set Poll List Command
Use the dlWrite function with the pOptArgs.usProtCommand field set to
DLI_PROT_SET_POLL_LIST to set the BSC 3270 poll list. The buffer pointed to by the pBuf
parameter contains a variable number of 8-bit bytes (up to 64) containing the control
unit (CU) numbers to poll. The
iBufLen parameter equals the number of bytes in the
poll list. When used on links configured as control stations, this command determines
which tributary stations are to be included in the general polling sequence. CU numbers
within the list may be in any order and duplication of CU numbers is allowed. If the
BSC 3270 software detects an illegal CU number in the list (i.e. not from 0 to 31, inclu-
sive), that CU is removed from the list. Unlike the other configuration commands, the
Set Poll List command can be issued when the link is either active or inactive. Figure 3–3
shows an example of the Set Poll List command. After the poll list is changed, the