User`s guide

58 DC 900-1339H
FMP Programmer’s Guide
If the localAck DLI configuration parameter is set to “no” (see the Freeway Data Link
Interface Reference Guide), the client application must make a
dlRead request to receive
the data acknowledge response for each
dlWrite data transfer request (the dlRead
pOptArgs.usProtCommand field is set to DLI_PROT_RESP_LOCAL_ACK by the DLI). One
DLI_PROT_RESP_LOCAL_ACK response (with the dlRead pOptArgs.iICPStatus field set to
1, signifying that one block of data was sent) is sent to the client computer after each
data block has been successfully transmitted to the remote computer, and can be treated
by the client program as the remote acknowledgment. Data acknowledgments are also
used to report transmission errors (as a response to a
dlRead request as described in
Section 3.5.2). The client application can use the data acknowledge response to monitor
the success or failure of transmitted data messages, or for regulating the number of out-
bound messages that the FMP software has pending transmission at any one time.
If the DLI
localAck configuration parameter is set to “yes” (which is the default), the
data acknowledge response is implied by a successful
dlWrite.
An unsuccessful
dlWrite data transfer request can return one of the following error
codes in the
dlRead pOptArgs.iICPStatus field (see Appendix C for error handling):
DLI_ICP_ERR_LINK_INACTIVE
The link is stopped.
DLI_ICP_ERR_BAD_MODE
The function request is not available for the requested
access mode; see Table 2–2 on page 33.
DLI_ICP_ERR_XMIT_TIMEOUT
The protocol software was unable to transmit the
data. This error occurs when some or all of the
modem signals are not present.
3.4.3.1 Send Normal Data
If your application needs to perform a Raw dlWrite, use the dlWrite function with the
pOptArgs.usProtCommand field set to DLI_PROT_SEND_NORM_DATA or
DLI_PROT_SEND_NORM_DATA_EOM to send normal data.