User`s guide

5: BSC 2780/3780 DLI Functions
DC 900-1340I 115
5.4 Overview of BSC 2780/3780 Requests using dlWrite
For BSC 2780/3780 the dlWrite function supports three dlWrite categories: commands,
information requests, and data transfer, which are discussed in detail in Section 5.4.1
through Section 5.4.3. Whether you use blocking or non-blocking I/O, each Raw
dlWrite request must be followed by a dlRead request to receive the command confirma-
tion, information requested, or acknowledgment of the data transfer. Section 5.5 dis-
cusses these different responses received using
dlRead.
In a typical BSC 2780/3780 application, some dlWrite requests use Raw operation; that
is, the optional arguments structure (page 114) is required to specify protocol-specific
information.
If your application is limited to interacting with Freeway only to exchange data with the
remote application, you can read and write using Normal operation. The
writeType DLI
configuration parameter (Table 7–2 on page 191) specifies the type of data to be
exchanged. If
writeType is set to “normal,” normal data with EOM is used
(Section 5.4.3.1); if
writeType is set to “transparent,” transparent data with EOM is used
(Section 5.4.3.2).
Caution
Take care not to confuse the terms “Normal operation” and “nor-
mal data.” Normal data can be sent using either Normal or Raw
operation.
Ta ble 5 –4 shows the BSC 2780/3780 DLI request codes for different categories of the
dlWrite function. Each request is explained in the following sections.
In addition to the command-specific error codes listed in the following sections, an
unsuccessful
dlWrite function can return one of the following error codes in the dlRead
pOptArgs.iICPStatus
field (see Appendix D for error handling):