User`s guide

80 DC 900-1340I
BSC Programmer’s Guide
3.5 Overview of BSC 3270 Responses using Raw dlRead
Ta ble 3 –10 shows the valid BSC 3270 codes sent to your application in response to a
Raw
dlRead request; the returned dlRead pOptArgs.usProtCommand field indicates the
response code. If the
dlRead return value is zero or positive, it indicates the number of
bytes read; if it is less than zero, an error has occurred. BSC error codes that can be asso-
ciated with the responses are returned in the
pOptArgs.iICPStatus field and are described
in Appendix D. When applicable, the DLI sets the MSB of the
pOptArgs.usProtCircuitID
field to the control unit (CU) number, and the LSB to the device unit (DU) number.
Note
The use of Normal dlRead requests (that is, without the optional
arguments parameter) is not recommended for BSC 3270 since
error reports would be indistinguishable from data received from
the remote application, and the application would be unable to
determine the CU/DU in the request.
The following types of data can be returned from the ICP:
• Normal and transparent received data
• BSC 3270 sense/status messages
• Error and confirmation responses
• Acknowledgments (if the localAck DLI configuration parameter is set to “no”)
• Reports in response to dlWrite information requests